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Title: BCKDHA-BCKDHB digenic gene therapy restores metabolic homeostasis in two mouse models and a calf with classic maple syrup urine disease Published: February 26, 2025 Publication: Science Translational Medicine

Authors: Jiaming Wang, Laura E. Poskitt, Jillian Gallagher, Erik G. Puffenberger, R. Max Wynn, Gauri Shisodia, David T. Chuang, Jonathan Beever, Donald L. Hardin, Karlla W. Brigatti, William C. Baker, Rachael Gately, Stephanie Bertrand, Ashlin Rodrigues, Hector R. Benatti, Toloo Taghian, Erin Hall, Rachel Prestigiacomo, Jialing Liang, Gong Chen, Xuntao Zhou, Lingzhi Ren, Nan Liu, Ran He, Qin Su, Jun Xie, Zhong Jiang, Alisha Gruntman, Heather Gray-Edwards, Guangping Gao, Kevin A. Strauss, Dan Wang

Abstract:
Classic maple syrup urine disease (MSUD) results from biallelic mutations in genes that encode the branched-chain α-ketoacid dehydrogenase E1α (BCKDHA), E1β (BCKDHB), or dihydrolipoamide branched-chain transacylase (DBT) subunits, which interact to form the mitochondrial BCKDH complex that decarboxylates ketoacid derivatives of leucine, isoleucine, and valine. MSUD is an inborn error of metabolism characterized by recurrent life-threatening neurologic crises and progressive brain injury that can only be managed with an exacting prescription diet or allogeneic liver transplant. To develop a gene replacement therapy for MSUD, we designed a dual-function recombinant adeno-associated virus serotype 9 (rAAV9) vector to deliver codon-optimized BCKDHA and BCKDHB (rAAV9.hA-BiP-hB) to the liver, muscle, heart, and brain. rAAV9.hA-BiP-hB restored coexpression of BCKDHA and BCKDHB as well as BCKDH holoenzyme activity in BCKDHA−/− HEK293T cells and did not perturb physiologic branched-chain amino acid homeostasis in wild-type mice at a systemic dose of 2.7 × 1014 vector genomes per kilogram. In two models of severe MSUD (Bckdha−/− and Bckdhb−/− mice) and a newborn calf homozygous for BCKDHA c.248C>T, one postnatal injection prevented perinatal death, normalized growth, restored coordinated expression of BCKDHA and BCKDHB in the skeletal muscle, liver, heart, and brain, and stabilized MSUD biomarkers in the face of high protein ingestion. In summary, we developed a one-time BCKDHA-BCKDHB systemic dual-gene replacement strategy that holds promise as a therapeutic alternative to prescription diet and liver transplant for treatment of MSUD types 1A and 1B, the two most common forms of MSUD in humans.
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Title: Preemptive dual therapy for children at risk for infantile-onset spinal muscular atrophy Published: May 31, 2024 Publication: Annals of Clinical and Translational Neurology

Authors: Susan E. Matesanz, Karlla W. Brigatti, Millie Young, Sabrina W. Yum, Kevin A. Strauss

Abstract:
Compare efficacy of gene therapy alone (monotherapy) or in combination with an SMN2 augmentation agent (dual therapy) for treatment of children at risk for spinal muscular atrophy type 1.
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Title: Neural-specific alterations in glycosphingolipid biosynthesis and cell signaling associated with two human ganglioside GM3 synthase deficiency variants Published: December 1, 2023 Publication: Human Molecular Genetics

Authors: Michelle Dookwah, Shannon K Wagner , Mayumi Ishihara, Seok-Ho Yu, Heidi Ulrichs, Michael J Kulik, Nadja Zeltner, Stephen Dalton, Kevin A Strauss, Kazuhiro Aoki, Richard Steet, Michael Tiemeyer

Abstract:
GM3 Synthase Deficiency (GM3SD) is a neurodevelopmental disorder resulting from pathogenic variants in the ST3GAL5 gene, which encodes GM3 synthase, a glycosphingolipid (GSL)-specific sialyltransferase. This enzyme adds a sialic acid to the terminal galactose of lactosylceramide (LacCer) to produce the monosialylated ganglioside GM3. In turn, GM3 is extended by other glycosyltransferases to generate nearly all the complex gangliosides enriched in neural tissue. Pathogenic mechanisms underlying the neural phenotypes associated with GM3SD are unknown. To explore how loss of GM3 impacts neural-specific glycolipid glycosylation and cell signaling, GM3SD patient fibroblasts bearing one of two different ST3GAL5 variants were reprogrammed to induced pluripotent stem cells (iPSCs) and then differentiated to neural crest cells (NCCs). GM3 and GM3-derived gangliosides were undetectable in cells carrying either variant, while LacCer precursor levels were elevated compared to wildtype (WT). NCCs of both variants synthesized elevated levels of neutral lacto- and globo-series, as well as minor alternatively sialylated GSLs compared to WT. Ceramide profiles were also shifted in GM3SD variant cells. Altered GSL profiles in GM3SD cells were accompanied by dynamic changes in the cell surface proteome, protein O-GlcNAcylation, and receptor tyrosine kinase abundance. GM3SD cells also exhibited increased apoptosis and sensitivity to erlotinib-induced inhibition of epidermal growth factor receptor signaling. Pharmacologic inhibition of O-GlcNAcase rescued baseline and erlotinib-induced apoptosis. Collectively, these findings indicate aberrant cell signaling during differentiation of GM3SD iPSCs and also underscore the challenge of distinguishing between variant effect and genetic background effect on specific phenotypic consequences.
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Title: Hypotonia and Failure to Thrive in an 8-month-old Infant Published: November 1, 2023 Publication: Pediatrics in Review

Authors: Sunil Muthusami, MD, MBBS, Laura Hatchman, MD, Vincent J. Carson, MD

Abstract:
An 8-month-old unimmunized boy presents to the emergency department with 10 days of progressive weakness. He has become limp and too weak to roll over or hold his bottle, and he is disinterested in feeding and has lost weight. His parents have been administering him sips of a reconstituted sports drink. On review of systems, he has no rashes, vomiting, dyspnea, or seizures. He had common cold–like symptoms 2 weeks earlier that spontaneously resolved. His medical history reveals a normal perinatal course. At age 1 month he was transitioned from breastfeeding to a homemade preparation of cow milk fortified with cod-liver oil, butter oil, molasses, beef gelatin, honey, and vitamin D. Parents report use of enemas to relieve the constipation that he has had for several months. He has had no primary care visits.
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Title: WiTNNess: An international natural history study of infantile-onset TNNT1 myopathy Published: August 25, 2023 Publication: Annals of Clinical and Translational Neurology

Authors: Kevin A. Strauss, Vincent J. Carson, Emilienne Bolettieri, Mariah Everett, Ashton Bollinger, Lauren E. Bowser, Keturah Beiler, Millie Young, Simon Edvardson, Nitay Fraenkel, Adele D'Amico, Enrico Bertini, Lokesh Lingappa, Devyani Chowdhury, Linda P. Lowes, Megan Iammarino, Lindsay N. Alfano, Karlla W. Brigatti

Abstract:
We created WiTNNess as a hybrid prospective/cross-sectional observational study to simulate a clinical trial for infantile-onset TNNT1 myopathy. Our aims were to identify populations for future trial enrollment, rehearse outcome assessments, specify endpoints, and refine trial logistics.
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Title: Rescue of GM3 synthase deficiency by spatially controlled, rAAV-mediated ST3GAL5 delivery Published: May 8, 2023 Publication: Journal of Clinical Investigation

Authors: Huiya Yang, Robert H Brown Jr, Dan Wang, Kevin A Strauss, Guangping Gao

Abstract:
GM3 synthase deficiency (GM3SD) is an infantile-onset epileptic encephalopathy syndrome caused by biallelic loss-of-function mutations in ST3GAL5. Loss of ST3GAL5 activity in humans results in systemic ganglioside deficiency and severe neurological impairment. No disease-modifying treatment is currently available. Certain recombinant adeno-associated viruses (rAAVs) can cross the blood-brain barrier to induce widespread, long-term gene expression in the CNS and represent a promising therapeutic strategy. Here, we show that a first-generation rAAV-ST3GAL5 replacement vector using a ubiquitous promoter restored tissue ST3GAL5 expression and normalized cerebral gangliosides in patient-derived induced pluripotent stem cell neurons and brain tissue from St3gal5-KO mice but caused fatal hepatotoxicity when administered systemically. In contrast, a second-generation vector optimized for CNS-restricted ST3GAL5 expression, administered by either the intracerebroventricular or i.v. route at P1, allowed for safe and effective rescue of lethality and behavior impairment in symptomatic GM3SD mice up to a year. These results support further clinical development of ST3GAL5 gene therapy.
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Title: Pathogenic variants in SLF2 and SMC5 cause segmented chromosomes and mosaic variegated hyperploidy Published: November 4, 2022 Publication: Nature Communications

Authors: Laura J Grange, John J Reynolds, Farid Ullah, Bertrand Isidor, Robert F Shearer, Xenia Latypova, Ryan M Baxley, Antony W Oliver, Anil Ganesh, Sophie L Cooke, Satpal S Jhujh, Gavin S McNee, Robert Hollingworth, Martin R Higgs, Toyoaki Natsume, Tahir Khan, Gabriel A Martos-Moreno, Sharon Chupp, Christopher G Mathew, David Parry, Michael A Simpson, Nahid Nahavandi, Zafer Yuksel, Mojgan Drasdo, Anja Kron, Petra Vogt, Annemarie Jonasson, Saad Ahmed Seth, Claudia Gonzaga-Jauregui, Karlla W Brigatti, Alexander P A Stegmann, Masato Kanemaki, Dragana Josifova, Yuri Uchiyama, Yukiko Oh, Akira Morimoto, Hitoshi Osaka, Zineb Ammous, Jesus Argente, Naomichi Matsumoto, Constance T R M Stumpel, Alexander M R Taylor, Andrew P Jackson, Anja-Katrin Bielinksy, Niels Mailand, Cedric Le Caignec, Erica E Davis, Grant S Stewart

Abstract:
Embryonic development is dictated by tight regulation of DNA replication, cell division and differentiation. Mutations in DNA repair and replication genes disrupt this equilibrium, giving rise to neurodevelopmental disease characterized by microcephaly, short stature and chromosomal breakage. Here, we identify biallelic variants in two components of the RAD18-SLF1/2-SMC5/6 genome stability pathway, SLF2 and SMC5, in 11 patients with microcephaly, short stature, cardiac abnormalities and anemia. Patient-derived cells exhibit a unique chromosomal instability phenotype consisting of segmented and dicentric chromosomes with mosaic variegated hyperploidy. To signify the importance of these segmented chromosomes, we have named this disorder Atelís (meaning - incomplete) Syndrome. Analysis of Atelís Syndrome cells reveals elevated levels of replication stress, partly due to a reduced ability to replicate through G-quadruplex DNA structures, and also loss of sister chromatid cohesion. Together, these data strengthen the functional link between SLF2 and the SMC5/6 complex, highlighting a distinct role for this pathway in maintaining genome stability.
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Title: Onasemnogene abeparvovec for presymptomatic infants with two copies of SMN2 at risk for spinal muscular atrophy type 1: the Phase III SPR1NT trial Published: June 17, 2022 Publication: Nature Medicine

Authors: Kevin A. Strauss, Michelle A. Farrar, Francesco Muntoni, Kayoko Saito, Jerry R. Mendell, Laurent Servais, Hugh J. McMillan, Richard S. Finkel, Kathryn J. Swoboda, Jennifer M. Kwon, Craig M. Zaidman, Claudia A. Chiriboga, Susan T. Iannaccone, Jena M. Krueger, Julie A. Parsons, Perry B. Shieh, Sarah Kavanagh, Sitra Tauscher-Wisniewski, Bryan E. McGill, Thomas A. Macek

Abstract:
SPR1NT (NCT03505099) was a Phase III, multicenter, single-arm study to investigate the efficacy and safety of onasemnogene abeparvovec for presymptomatic children with biallelic SMN1 mutations treated at ≤6 weeks of life. Here, we report final results for 14 children with two copies of SMN2, expected to develop spinal muscular atrophy (SMA) type 1. Efficacy was compared with a matched Pediatric Neuromuscular Clinical Research natural-history cohort (n = 23). All 14 enrolled infants sat independently for ≥30 seconds at any visit ≤18 months (Bayley-III item #26; P < 0.001; 11 within the normal developmental window). All survived without permanent ventilation at 14 months as per protocol; 13 maintained body weight (≥3rd WHO percentile) through 18 months. No child used nutritional or respiratory support. No serious adverse events were considered related to treatment by the investigator. Onasemnogene abeparvovec was effective and well-tolerated for children expected to develop SMA type 1, highlighting the urgency for universal newborn screening.
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Title: Onasemnogene abeparvovec for presymptomatic infants with three copies of SMN2 at risk for spinal muscular atrophy: the Phase III SPR1NT trial Published: June 17, 2022 Publication: Nature Medicine

Authors: Kevin A. Strauss, Michelle A. Farrar, Francesco Muntoni, Kayoko Saito, Jerry R. Mendell, Laurent Servais, Hugh J. McMillan, Richard S. Finkel, Kathryn J. Swoboda, Jennifer M. Kwon, Craig M. Zaidman, Claudia A. Chiriboga, Susan T. Iannaccone, Jena M. Krueger, Julie A. Parsons, Perry B. Shieh, Sarah Kavanagh, Melissa Wigderson, Sitra Tauscher-Wisniewski, Bryan E. McGill, Thomas A. Macek

Abstract:
Most children with biallelic SMN1 deletions and three SMN2 copies develop spinal muscular atrophy (SMA) type 2. SPR1NT (NCT03505099), a Phase III, multicenter, single-arm trial, investigated the efficacy and safety of onasemnogene abeparvovec for presymptomatic children with biallelic SMN1 mutations treated within six postnatal weeks. Of 15 children with three SMN2 copies treated before symptom onset, all stood independently before 24 months (P < 0.0001; 14 within normal developmental window), and 14 walked independently (P < 0.0001; 11 within normal developmental window). All survived without permanent ventilation at 14 months; ten (67%) maintained body weight (≥3rd WHO percentile) without feeding support through 24 months; and none required nutritional or respiratory support. No serious adverse events were considered treatment-related by the investigator. Onasemnogene abeparvovec was effective and well-tolerated for presymptomatic infants at risk of SMA type 2, underscoring the urgency of early identification and intervention.
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Title: Domino liver transplant from a donor with maple syrup urine disease into a recipient with phenylketonuria Published: April 21, 2022 Publication: Molecular Genetics and Metabolism Reports

Authors: Vikram K Raghu, Steven F Dobrowolski, Rakesh Sindhi, Kevin A Strauss, George V Mazariegos, Jerry Vockley, Kyle Soltys

Abstract:
Classical phenylketonuria (PKU) presents a unique challenge for women of child-bearing age. In the context of pregnancy, poorly controlled hyperphenylalaninemia can result in a devastating constellation of outcomes for the baby referred to as the maternal PKU Syndrome. We present the case of a woman with classical PKU unable to maintain a restricted diet and refractory to pharmacological therapies. She elected to undergo a domino liver transplant, receiving an organ from a donor with classical branched chain ketoacid dehydrogenase deficiency (maple syrup urine disease). Plasma phenylalanine concentrations normalized within a few days after transplant and remained so on an unrestricted diet during the first year of follow-up. The patient reports subjective improvements in mood, energy level, and overall quality of life. In the appropriate clinical setting, liver transplant should be considered to provide metabolic stability for PKU patients, particularly women of childbearing age.
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Title: Impact of parental relatedness on reproductive outcomes among the Old Order Amish of Lancaster County Published: April 20, 2022 Publication: American Journal of Medical Genetics Part A

Authors: Megan T Lynch, Kristin A Maloney, Toni I Pollin, Elizabeth A Streeten, Erik G Puffenberger, Kevin A Strauss, Regeneron Genetics Center, Alan R Shuldiner, Braxton D Mitchell

Abstract:
Genetically isolated populations that arise due to recent bottleneck events have reduced genetic variation reflecting the common set of founders. Increased genetic relatedness among members of isolated populations puts them at increased risk for some recessive disorders that are rare in outbred populations. To assess the burden on reproductive health, we compared frequencies of adverse reproductive outcomes between Amish couples who were both heterozygous carriers of a highly penetrant pathogenic or likely pathogenic variant and noncarrier couples from the same Amish community. In addition, we evaluated whether overall genetic relatedness of parents was associated with reproductive outcomes. Of the 1824 couples included in our study, 11.1% were at risk of producing a child with an autosomal recessive disorder. Carrier couples reported a lower number of miscarriages compared to noncarrier couples (p = 0.02), although the number of stillbirths (p = 0.3), live births (p = 0.9), and number of pregnancies (p = 0.9) did not differ significantly between groups. In contrast, higher overall relatedness between spouses was positively correlated with number of live births (p < 0.0001), pregnancies (p < 0.0001), and stillbirths (p = 0.03), although not with the number of miscarriages (p = 0.4). These results highlight a complex association between relatedness of parents and reproductive health outcomes in this community.
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Title: Clinical characterization of familial hypercholesterolemia due to an amish founder mutation in Apolipoprotein B Published: March 17, 2022 Publication: BMC Cardiovascular Disorders

Authors: Katie B Williams, Michael Horst, Millie Young, Christine Pascua, Erik G Puffenberger, Karlla W Brigatti, Claudia Gonzaga-Jauregui, Alan R Shuldiner, Samuel Gidding, Kevin A Strauss, Devyani Chowdhury

Abstract:
Familial hypercholesterolemia (FH) due to a founder variant in Apolipoprotein B (ApoBR3500Q) is reported in 12% of the Pennsylvania Amish community. By studying a cohort of ApoBR3500Q heterozygotes and homozygotes, we aimed to characterize the biochemical and cardiac imaging features in children and young adults with a common genetic background and similar lifestyle.
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Title: Disease burden and management of Crigler-Najjar syndrome: Report of a world registry Published: March 11, 2022 Publication: Liver International

Authors: Sem J Aronson, Norman Junge, Mediha Trabelsi, Wided Kelmemi, Aurelie Hubert, Karlla W Brigatti, Michael D Fox, Robert J de Knegt, Johanna C Escher, Virginia M Ginocchio, Raffaele Iorio, Yan Zhu, Figen Ozcay, Fakher Rahim, Mortada H F El-Shabrawi, Eyal Shteyer, Angelo Di Giorgio, Lorenzo D'Antiga, Federico Mingozzi, Nicola Brunetti-Pierri, Kevin A Strauss, Philippe Labrune, Ridha Mrad, Ulrich Baumann, Piter J Bosma, CureCN Consortium

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Title: NPRL3 loss alters neuronal morphology, mTOR localization, cortical lamination, and seizure threshold Published: February 8, 2022 Publication: Brain

Authors: Philip H Iffland, Mariah E Everett, Katherine M Cobb-Pitstick, Lauren E Bowser, Allan E Barnes, Janice K Babus, Andrea J Romanowski, Marianna Baybis, Soad Elziny, Erik G Puffenberger, Claudia Gonzaga-Jauregui, Alexandros Poulopoulos, Vincent J Carson, Peter B Crino

Abstract:
Mutations in nitrogen permease regulator-like 3 (NPRL3), a component of the GATOR1 complex within the mechanistic target of rapamycin (mTOR) pathway, are associated with epilepsy and malformations of cortical development.
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Title: Nusinersen by subcutaneous intrathecal catheter for symptomatic spinal muscular atrophy patients with complex spine anatomy Published: January 1, 2022 Publication: Muscle & Nerve

Authors: Vincent J Carson, Millie Young, Karlla W Brigatti, Donna L Robinson, Robert M Reed, Jihee Sohn, Marco Petrillo, Wildon Farwell, Freeman Miller, Kevin A Strauss

Abstract:
Intrathecal administration of nusinersen is challenging in patients with spinal muscular atrophy (SMA) who have spine deformities or fusions. We prospectively studied the safety and efficacy of nusinersen administration via an indwelling subcutaneous intrathecal catheter (SIC) for SMA patients with advanced disease.
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Title: APC7 mediates ubiquitin signaling in constitutive heterochromatin in the developing mammalian brain Published: December 22, 2021 Publication: Molecular Cell

Authors: Cole J. Ferguson, Olivia Urso, Tatyana Bodrug, Brandon M. Gassaway, Edmond R. Watson, Jesuraj R. Prabu, Pablo Lara-Gonzalez, Raquel C. Martinez-Chacin, Dennis Y. Wu, Karlla W. Brigatti, Erik G. Puffenberger, Cora M. Taylor, Barbara Haas-Givler, Robert N. Jinks, Kevin A. Strauss, Arshad Desai, Harrison W. Gabel, Steven P. Gygi, Brenda A. Schulman, Nicholas G. Brown, Azad Bonni

Abstract:
Neurodevelopmental cognitive disorders provide insights into mechanisms of human brain development. Here, we report an intellectual disability syndrome caused by the loss of APC7, a core component of the E3 ubiquitin ligase anaphase promoting complex (APC). In mechanistic studies, we uncover a critical role for APC7 during the recruitment and ubiquitination of APC substrates. In proteomics analyses of the brain from mice harboring the patient-specific APC7 mutation, we identify the chromatin-associated protein Ki-67 as an APC7-dependent substrate of the APC in neurons. Conditional knockout of the APC coactivator protein Cdh1, but not Cdc20, leads to the accumulation of Ki-67 protein in neurons in vivo, suggesting that APC7 is required for the function of Cdh1-APC in the brain. Deregulated neuronal Ki-67 upon APC7 loss localizes predominantly to constitutive heterochromatin. Our findings define an essential function for APC7 and Cdh1-APC in neuronal heterochromatin regulation, with implications for understanding human brain development and disease.
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Title: Long-term liver transplant outcomes for progressive familial intrahepatic cholestasis type 1: The Pittsburgh experience Published: December 1, 2021 Publication: Pediatric Transplantation

Authors: Sarah A F Henkel, Claudia M Salgado, Miguel Reyes-Mugica, Kyle A Soltys, Kevin Strauss, George V Mazariegos, Robert H Squires, Patrick J McKiernan, Xingyu Zhang, James E Squires

Abstract:
Background: Progressive familial intrahepatic cholestasis type 1 (PFIC1) arises from biallelic variants in the ATP8B1 gene that annul FIC1 activity, resulting in progressive liver disease. Liver transplant (LT) is indicated in refractory disease; however, post-LT complications including worsening diarrhea and steatohepatitis progressing to fibrosis with graft loss have been reported. We aim to describe long-term outcomes of PFIC1 LT recipients at our center, focusing on the histological changes of the allografts. Methods: We assessed 7 PFIC1 patients post-LT at the Children's Hospital of Pittsburgh (CHP). All pre-transplant, explant, and sequential post-transplant pathology samples were reviewed. Continuous data are presented as the mean ± SD. We compared the pre- and post-transplant height and weight z-scores using Wilcoxon signed-rank test. Results: Seven (29% male) patients with PFIC1 received a LT (n = 6) or had post-LT care (n = 1) at CHP. Six had confirmed or suspected identical genetic. At a mean follow-up of 10.9 years, both patient survival and graft survival were 100%. Diarrhea persisted (n = 3) or newly developed (n = 4) in all patients after LT contributing to ongoing growth failure, with mean z-scores -2.63 (weight) and -2.98 (height) at follow-up. Histologically, allograft steatosis was common but was not accompanied by significant inflammation, ballooning, or fibrosis. Conclusion: We show that extrahepatic disease persists and near-universal allograft steatosis occurs. However, at a mean follow-up period of over 10 years, no patients developed steatohepatitis or significant fibrosis, and both patient survival and graft survival are excellent.
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Title: Mendelian disease research in the Plain populations of Lancaster County, Pennsylvania Published: November 10, 2021 Publication: American Journal of Medical Genetics Part A

Authors: Erik G. Puffenberger

Abstract:

Founder populations have long contributed to our knowledge of rare disease genes and phenotypes. From the pioneering work of Dr. Victor McKusick to today, research in these groups has shed light on rare recessive phenotypes, expanded the clinical spectrum of disease, and facilitated disease gene identification. Current clinical and research studies in these special groups augment the wealth of knowledge already gained, provide new insights into emerging problems such as variant interpretation and reduced penetrance, and contribute to the development of novel therapies for rare genetic diseases. Clinical developments over the past 30 years have altered the fundamental relationship with the Lancaster Plain communities: research has become more collaborative, and the knowledge imparted by these studies is now being harnessed to provide cutting-edge translational medicine to the very community of vulnerable individuals who need it most.

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Title: Nusinersen by subcutaneous intrathecal catheter for symptomatic spinal muscular atrophy patients with complex spine anatomy Published: October 20, 2021 Publication: Muscle & Nerve

Authors: Vincent J. Carson MD, Millie Young RNC, Karlla W. Brigatti MS, CGC, Donna L. Robinson, CRNP, Robert M. Reed MD, Jihee Sohn PhD, Marco Petrillo PhD, Wildon Farwell MD, PhD, Freeman Miller MD, Kevin A. Strauss MD

Abstract:
Introduction/Aims: Intrathecal administration of nusinersen is challenging in patients with spinal muscular atrophy (SMA) who have spine deformities or fusions. We prospectively studied the safety and efficacy of nusinersen administration via an indwelling subcutaneous intrathecal catheter (SIC) for SMA patients with advanced disease. Methods: Seventeen participants commenced nusinersen therapy between 2.7 and 31.5 years of age and received 9 to 12 doses via SIC. Safety was assessed in all participants. A separate efficacy analysis comprised 11 nonambulatory, treatment-naive SMA patients (18.1 ± 6.8 years) with three SMN2 copies and complex spine anatomy. Results: In the safety analysis, 14 treatment-related adverse events (AEs) occurred among 12 (71%) participants; all were related to the SIC and not nusinersen. Device- related AEs interfered with 2.5% of nusinersen doses. Four SICs (24%) required surgical revision due to mechanical malfunction with or without cerebrospinal fluid leak (n = 2), and one (6%) was removed due to Staphylococcus epidermidis meningitis. In the efficacy analysis, mean performance on the nine-hole peg test improved in domi- nant (15.9%, P = 0.012) and nondominant (19.0%, P = 0.008) hands and grip strength increased by 44.9% (P = 0.031). We observed no significant changes in motor scales, muscle force, pulmonary function, or SMA biomarkers. All participants in the efficacy cohort reported one or more subjective improvement(s) in endurance, purposeful hand use, arm strength, head control, and/or speech. Discussion: For SMA patients with complex spine anatomy, the SIC allows for reliable outpatient administration of nusinersen that results in meaningful improvements in upper limb function, but introduces risks of technical malfunction and iatrogenic infection.
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Title: Metabolic Control and “Ideal” Outcomes in Liver Transplantation for Maple Syrup Urine Disease Published: October 1, 2021 Publication: The Journal of Pediatrics

Authors: Caroline B Ewing, Kyle A Soltys, Kevin A Strauss, Rakesh Sindhi, Jerry Vockley, Patrick McKiernan, Robert H Squires, Geoffrey Bond, Armando Ganoza, Ajai Khanna, George V Mazariegos, James E Squires

Abstract:
To assess outcomes following liver transplantation for maple syrup urine disease by determining attainment and sustainability of metabolic control and apply an "ideal" outcome composite in long-term survivors.
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Title: Clinical Trial and Postmarketing Safety of Onasemnogene Abeparvovec Therapy Published: October 1, 2021 Publication: Drug Safety

Authors: John W. Day, Jerry R Mendell, Eugenio Mercuri, Richard S Finkel, Kevin A. Strauss, Aaron Kleyn, Sitra Tauscher-Wisniewski, Francis Fonyuy Tukov, Sandra P Reyna, Deepa H Chand

Abstract:
This is the first description of safety data for intravenous onasemnogene abeparvovec, the only approved systemically administered gene-replacement therapy for spinal muscular atrophy.
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Title: A biallelic SNIP1 Amish founder variant causes a recognizable neurodevelopmental disorder Published: September 27, 2021 Publication: PLOS Genetics

Authors: Zineb Ammous, Lettie E Rawlins, Hannah Jones, Joseph S Leslie, Olivia Wenger, Ethan Scott, Jim Deline, Tom Herr, Rebecca Evans, Angela Scheid, Joanna Kennedy, Barry A Chioza, Ryan M Ames, Harold E Cross, Erik G Puffenberger, Lorna Harries, Emma L Baple, Andrew H Crosby

Abstract:
SNIP1 (Smad nuclear interacting protein 1) is a widely expressed transcriptional suppressor of the TGF-β signal-transduction pathway which plays a key role in human spliceosome function. Here, we describe extensive genetic studies and clinical findings of a complex inherited neurodevelopmental disorder in 35 individuals associated with a SNIP1 NM_024700.4:c.1097A>G, p.(Glu366Gly) variant, present at high frequency in the Amish community. The cardinal clinical features of the condition include hypotonia, global developmental delay, intellectual disability, seizures, and a characteristic craniofacial appearance. Our gene transcript studies in affected individuals define altered gene expression profiles of a number of molecules with well-defined neurodevelopmental and neuropathological roles, potentially explaining clinical outcomes. Together these data confirm this SNIP1 gene variant as a cause of an autosomal recessive complex neurodevelopmental disorder and provide important insight into the molecular roles of SNIP1, which likely explain the cardinal clinical outcomes in affected individuals, defining potential therapeutic avenues for future research.
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Title: Cortical overgrowth in a preclinical forebrain organoid model of CNTNAP2-associated autism spectrum disorder Published: September 1, 2021 Publication: Nature Communications

Authors: Job O de Jong, Ceyda Llapashtica, Matthieu Genestine, Kevin Strauss, Frank Provenzano, Yan Sun, Huixiang Zhu, Giuseppe P Cortese, Francesco Brundu, Karlla W Brigatti, Barbara Corneo, Bianca Migliori, Raju Tomer, Steven A Kushner, Christoph Kellendonk, Jonathan A Javitch, Bin Xu, Sander Markx

Abstract:
We utilized forebrain organoids generated from induced pluripotent stem cells of patients with a syndromic form of Autism Spectrum Disorder (ASD) with a homozygous protein-truncating mutation in CNTNAP2, to study its effects on embryonic cortical development. Patients with this mutation present with clinical characteristics of brain overgrowth. Patient-derived forebrain organoids displayed an increase in volume and total cell number that is driven by increased neural progenitor proliferation. Single-cell RNA sequencing revealed PFC-excitatory neurons to be the key cell types expressing CNTNAP2. Gene ontology analysis of differentially expressed genes (DEgenes) corroborates aberrant cellular proliferation. Moreover, the DEgenes are enriched for ASD-associated genes. The cell-type-specific signature genes of the CNTNAP2-expressing neurons are associated with clinical phenotypes previously described in patients. The organoid overgrowth phenotypes were largely rescued after correction of the mutation using CRISPR-Cas9. This CNTNAP2-organoid model provides opportunity for further mechanistic inquiry and development of new therapeutic strategies for ASD.
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Title: De novo and bi-allelic variants in AP1G1 cause neurodevelopmental disorder with developmental delay, intellectual disability, and epilepsy Published: July 1, 2021 Publication: The American Journal of Human Genetics

Authors: Muhammad A Usmani, Zubair M Ahmed, Magini Pamela, Victor Murcia Pienkowski, Kristen J Rasmussen, Rebecca Hernan, Faiza Rasheed, Mureed Hussain, Mohsin Shahzad, Brendan C Lanpher, Zhiyv Niu, Foong-Yen Lim, Tommaso Pippucci, Rafal Ploski, Verena Kraus, Karolina Matuszewska, Flavia Palombo, Jessica Kianmahd, UCLA Clinical Genomics Center; Julian A Martinez-Agosto, Hane Lee, Emma Colao, M Mahdi Motazacker, Karlla W Brigatti, Erik G Puffenberger, S Amer Riazuddin, Claudia Gonzaga-Jauregui, Wendy K Chung, Matias Wagner, Matthew J Schultz, Marco Seri, Anneke J A Kievit, Nicola Perrotti, J S Klein Wassink-Ruiter, Hans van Bokhoven, Sheikh Riazuddin, Saima Riazuddin

Abstract:
Adaptor protein (AP) complexes mediate selective intracellular vesicular trafficking and polarized localization of somatodendritic proteins in neurons. Disease-causing alleles of various subunits of AP complexes have been implicated in several heritable human disorders, including intellectual disabilities (IDs). Here, we report two bi-allelic (c.737C>A [p.Pro246His] and c.1105A>G [p.Met369Val]) and eight de novo heterozygous variants (c.44G>A [p.Arg15Gln], c.103C>T [p.Arg35Trp], c.104G>A [p.Arg35Gln], c.229delC [p.Gln77Lys∗11], c.399_400del [p.Glu133Aspfs∗37], c.747G>T [p.Gln249His], c.928-2A>C [p.?], and c.2459C>G [p.Pro820Arg]) in AP1G1, encoding gamma-1 subunit of adaptor-related protein complex 1 (AP1γ1), associated with a neurodevelopmental disorder (NDD) characterized by mild to severe ID, epilepsy, and developmental delay in eleven families from different ethnicities. The AP1γ1-mediated adaptor complex is essential for the formation of clathrin-coated intracellular vesicles. In silico analysis and 3D protein modeling simulation predicted alteration of AP1γ1 protein folding for missense variants, which was consistent with the observed altered AP1γ1 levels in heterologous cells. Functional studies of the recessively inherited missense variants revealed no apparent impact on the interaction of AP1γ1 with other subunits of the AP-1 complex but rather showed to affect the endosome recycling pathway. Knocking out ap1g1 in zebrafish leads to severe morphological defect and lethality, which was significantly rescued by injection of wild-type AP1G1 mRNA and not by transcripts encoding the missense variants. Furthermore, microinjection of mRNAs with de novo missense variants in wild-type zebrafish resulted in severe developmental abnormalities and increased lethality. We conclude that de novo and bi-allelic variants in AP1G1 are associated with neurodevelopmental disorder in diverse populations.
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Title: AAV-Mediated Gene Therapy for Glycosphingolipid Biosynthesis Deficiencies Published: June 1, 2021 Publication: Trends in Molecular Medicine

Authors: Huiya Yang, Robert H Brown Jr, Dan Wang, Kevin A Strauss, Guangping Gao

Abstract:
De novo glycosphingolipid (GSL) biosynthesis defects cause severe neurological diseases, including hereditary sensory and autonomic neuropathy type 1A (HSAN1A), GM3 synthase deficiency, and hereditary spastic paraplegia type 26 (HSPG26), each lacking effective treatment. Recombinant adeno-associated virus (AAV)-mediated gene therapy has emerged as a powerful treatment for monogenic diseases and might be particularly suitable for these neurological conditions.
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Title: A recurring NFS1 pathogenic variant causes a mitochondrial disorder with variable intra-familial patient outcomes Published: December 30, 2020 Publication: Molecular Genetics and Metabolism Reports

Authors: Tova Hershkovitz, Alina Kurolap, Galit Tal, Tamar Paperna, Adi Mory, Jeffery Staples, Karlla W. Brigatti, Regeneron Genetics Center; Claudia Gonzaga-Jauregui, Elena Dumin, Ann Saada, Hanna Mandel, Hagit Baris Feldman

Abstract:
Iron‑sulfur clusters (FeSCs) are vital components of a variety of essential proteins, most prominently within mitochondrial respiratory chain complexes I-III; Fe-S assembly and distribution is performed via multi-step pathways. Variants affecting several proteins in these pathways have been described in genetic disorders, including severe mitochondrial disease. Here we describe a Christian Arab kindred with two infants that died due to mitochondrial disorder involving Fe-S containing respiratory chain complexes and a third sibling who survived the initial crisis. A homozygous missense variant in NFS1: c.215G>A; p.Arg72Gln was detected by whole exome sequencing. The NFS1 gene encodes a cysteine desulfurase, which, in complex with ISD11 and ACP, initiates the first step of Fe-S formation. Arginine at position 72 plays a role in NFS1-ISD11 complex formation; therefore, its substitution with glutamine is expected to affect complex stability and function. Interestingly, this is the only pathogenic variant ever reported in the NFS1 gene, previously described once in an Old Order Mennonite family presenting a similar phenotype with intra-familial variability in patient outcomes. Analysis of datasets from both populations did not show a common haplotype, suggesting this variant is a recurrent de novo variant. Our report of the second case of NFS1-related mitochondrial disease corroborates the pathogenicity of this recurring variant and implicates it as a hot-spot variant. While the genetic resolution allows for prenatal diagnosis for the family, it also raises critical clinical questions regarding follow-up and possible treatment options of severely affected and healthy homozygous individuals with mitochondrial co-factor therapy or cysteine supplementation.
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Title: Liver transplant for inherited metabolic disease among siblings Published: November 1, 2020 Publication: Clinical Transplantation

Authors: Patrick J McKiernan, James E Squires, Robert H Squires, Jerry Vockley, George V Mazariegos, Kyle Soltys, Armando Ganoza, Kevin Strauss, Ajai Khanna, Rakesh Sindhi

Abstract:
Liver transplantation is a successful option for inherited metabolic disease yet little is published on the outcome among siblings. We report outcomes of siblings who have undergone liver transplantation for metabolic disease in a single program. Seventy-one siblings (35 males) from 33 individual families underwent liver transplantation since 1982. Outcomes were compared over three consecutive eras. Twenty-eight families had two siblings, four had three siblings, and one had four siblings. In half of families where dates of listing were known, siblings were listed simultaneously. Mean (SD) age at listing for the oldest and second sibling was 13.2 (7.1) and 9.8 (5.7) years, respectively (p < .01). In 18/33 families, the oldest sibling underwent transplantation first. Mean (SD) age at transplant fell from the oldest to second sibling from 12.9 (7.2) to 9.5 (6.3) years, respectively (p < .001). Ten-year patient survival was 83.5% which improved over the eras: era 1 (1982-1994) 65.0%, era 2 (1995-2007) 87.5%, and era 3 (2008-2019) 93.8%: p < .03. Sex, age at transplant, order of transplant, and presence of structural liver disease did not significantly impact survival. When siblings undergo liver transplant for inherited metabolic disease, later siblings are listed and transplanted at a significantly younger age.
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Title: Glutaric acidemia type 1: Treatment and outcome of 168 patients over three decades Published: November 1, 2020 Publication: Molecular Genetics and Metabolism

Authors: Kevin A. Strauss, Katie B. Williams, Vincent J. Carson, Laura Poskitt, Lauren E. Bowser, Millie Young, Donna L. Robinson, Christine Hendrickson, Keturah Beiler, Cora M. Taylor, Barbara Haas-Givler, Jennifer Hailey, Stephanie Chopko, Erik G. Puffenberger, Karlla W. Brigatti, Freeman Miller, D. Holmes Morton

Abstract:
Glutaric acidemia type 1 (GA1) is a disorder of cerebral organic acid metabolism resulting from biallelic mutations of GCDH. Without treatment, GA1 causes striatal degeneration in >80% of affected children before two years of age. We analyzed clinical, biochemical, and developmental outcomes for 168 genotypically diverse GA1 patients managed at a single center over 31 years, here separated into three treatment cohorts: children in Cohort I (n = 60; DOB 2006–2019) were identified by newborn screening (NBS) and treated prospectively using a standardized protocol that included a lysine-free, arginine-enriched metabolic formula, enteral l-carnitine (100 mg/kg•day), and emergency intravenous (IV) infusions of dextrose, saline, and l-carnitine during illnesses; children in Cohort II (n = 57; DOB 1989–2018) were identified by NBS and treated with natural protein restriction (1.0–1.3 g/kg•day) and emergency IV infusions; children in Cohort III (n = 51; DOB 1973–2016) did not receive NBS or special diet. The incidence of striatal degeneration in Cohorts I, II, and III was 7%, 47%, and 90%, respectively (p < .0001). No neurologic injuries occurred after 19 months of age. Among uninjured children followed prospectively from birth (Cohort I), measures of growth, nutritional sufficiency, motor development, and cognitive function were normal. Adherence to metabolic formula and l-carnitine supplementation in Cohort I declined to 12% and 32%, respectively, by age 7 years. Cessation of strict dietary therapy altered plasma amino acid and carnitine concentrations but resulted in no serious adverse outcomes. In conclusion, neonatal diagnosis of GA1 coupled to management with lysine-free, arginine-enriched metabolic formula and emergency IV infusions during the first two years of life is safe and effective, preventing more than 90% of striatal injuries while supporting normal growth and psychomotor development. The need for dietary interventions and emergency IV therapies beyond early childhood is uncertain.
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Title: Biochemical phenotype and its relationship to treatment in 16 individuals with PCCB c.1606A>G (p.Asn536Asp) variant propionic acidemia Published: November 1, 2020 Publication: Molecular Genetics and Metabolism

Authors: Olivia Wenger, Miraides Brown, Brandon Smith, Devyani Chowdhury, Andrew H Crosby, Emma L Baple, Mark Yoder, William Laxen, Silvia Tortorelli, Kevin A Strauss

Abstract:
Propionic acidemia (PA) is caused by inherited deficiency of mitochondrial propionyl-CoA carboxylase (PCC) and results in significant neurodevelopmental and cardiac morbidity. However, relationships among therapeutic intervention, biochemical markers, and disease progression are poorly understood. Sixteen individuals homozygous for PCCB c.1606A > G (p.Asn536Asp) variant PA participated in a two-week suspension of therapy. Standard metabolic markers (plasma amino acids, blood spot methylcitrate, plasma/urine acylcarnitines, urine organic acids) were obtained before and after stopping treatment. These same markers were obtained in sixteen unaffected siblings. Echocardiography and electrocardiography were obtained from all subjects. We characterized the baseline biochemical phenotype of untreated PCCB c.1606A > G homozygotes and impact of treatment on PCC deficiency biomarkers. Therapeutic regimens varied widely. Suspension of therapy did not significantly alter branched chain amino acid levels, their alpha-ketoacid derivatives, or urine ketones. Carnitine supplementation significantly increased urine propionylcarnitine and its ratio to total carnitine. Methylcitrate blood spot and urine levels did not correlate with other biochemical measures or cardiac outcomes. Treatment of PCCB c.1606A > G homozygotes with protein restriction, prescription formula, and/or various dietary supplements has a limited effect on core biomarkers of PCC deficiency. These patients require further longitudinal study with standardized approaches to better understand the relationship between biomarkers and disease burden.
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Title: De Novo and Inherited Variants in GBF1 are Associated with Axonal Neuropathy Caused by Golgi Fragmentation Published: October 1, 2020 Publication: The American Journal of Human Genetics

Authors: Natalia Mendoza-Ferreira, Mert Karakaya, Nur Cengiz, Danique Beijer, Karlla W. Brigatti, Claudia Gonzaga-Jauregui, Nico Fuhrmann, Irmgard Holker, Maximilian P. Thelen, Sebastian Zetsche, Roman Rombo, Erik G. Puffenberger, Peter De Jonghe, Tine Deconinck, Stephan Zuchner, Kevin A. Strauss, Vincent Carson, Bertold Schrank, Gilbert Wunderlich, Jonathan Baets, Brunhilde Wirth

Abstract:
Distal hereditary motor neuropathies (HMNs) and axonal Charcot-Marie-Tooth neuropathy (CMT2) are clinically and genetically heterogeneous diseases characterized primarily by motor neuron degeneration and distal weakness. The genetic cause for about half of the individuals affected by HMN/CMT2 remains unknown. Here, we report the identification of pathogenic variants in GBF1 (Golgi brefeldin A-resistant guanine nucleotide exchange factor 1) in four unrelated families with individuals affected by sporadic or dominant HMN/CMT2. Genomic sequencing analyses in seven affected individuals uncovered four distinct heterozygous GBF1 variants, two of which occurred de novo. Other known HMN/CMT2-implicated genes were excluded. Affected individuals show HMN/CMT2 with slowly progressive distal muscle weakness and musculoskeletal deformities. Electrophysiological studies confirmed axonal damage with chronic neurogenic changes. Three individuals had additional distal sensory loss. GBF1 encodes a guanine-nucleotide exchange factor that facilitates the activation of members of the ARF (ADP-ribosylation factor) family of small GTPases. GBF1 is mainly involved in the formation of coatomer protein complex (COPI) vesicles, maintenance and function of the Golgi apparatus, and mitochondria migration and positioning. We demonstrate that GBF1 is present in mouse spinal cord and muscle tissues and is particularly abundant in neuropathologically relevant sites, such as the motor neuron and the growth cone. Consistent with the described role of GBF1 in Golgi function and maintenance, we observed marked increase in Golgi fragmentation in primary fibroblasts derived from all affected individuals in this study. Our results not only reinforce the existing link between Golgi fragmentation and neurodegeneration but also demonstrate that pathogenic variants in GBF1 are associated with HMN/CMT2.
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Title: Orthopaedic manifestations of glutaric acidemia Type 1 Published: August 4, 2020 Publication: Journal of Children's Orthopaedics

Authors: Ahmet Imerci, Kevin A. Strauss, Geovanny F. Oleas-Santillan, Freeman Miller

Abstract:
Glutaric acidemia type 1 (GA1), a rare hereditary metabolic disease caused by biallelic mutations of GCDH, can result in acute or insidious striatal degeneration within the first few years of life. We reviewed the orthopaedic sequelae and management of 114 neurologically injured patients with a confirmed molecular diagnosis of GA1.
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Title: Crigler-Najjar Syndrome Type 1: Pathophysiology, Natural History, and Therapeutic Frontier Published: June 1, 2020 Publication: Hepatology

Authors: Strauss KA, Ahlfors CE, Soltys K, Mazariegos GV, Young M, Bowser LE, Fox MD, Squires JE, McKiernan P, Brigatti KW, Puffenberger EG, Carson VJ, Vreman HJ

Abstract:
We describe the pathophysiology, treatment, and outcome of Crigler-Najjar type 1 syndrome (CN1) in 28 UGT1A1 c.222C>A homozygotes followed for 520 aggregate patient-years.
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Title: Disease burden of Crigler-Najjar syndrome: systematic review and future perspectives Published: April 1, 2020 Publication: Journal of Gastroenterology and Hepatology

Authors: Dhawan A, Lawlor MW, Mazariegos GV, McKiernan P, Squires JE, Strauss KA, Gupta D, James E, Prasad S

Abstract:
Crigler-Najjar syndrome (CNS) results from biallelic mutations of UGT1A1 causing partial or total loss of uridine 5'-diphosphate glucuronyltransferase activity leading to unconjugated hyperbilirubinemia and its attendant risk for irreversible neurological injury (kernicterus). CNS is exceedingly rare and has been only partially characterized through relatively small studies, each comprising between two and 57 patients.
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Title: RSRC1 loss-of-function variants cause mild to moderate autosomal recessive intellectual disability Published: April 1, 2020 Publication: Brain

Authors: Marcello Scala, Majid Mojarrad, Saima Riazuddin, Karlla W. Brigatti, Zineb Ammous, Julie S Cohen, Heba Hosny, Muhammad A Usmani, Mohsin Shahzad, Sheikh Riazuddin, Valentina Stanley, Atiye Eslahi, Richard E Person, Hasnaa M Elbendary, Anne M Comi, Laura Poskitt, Vincenzo Salpietro, Queen Square Genomics, Jill A Rosenfeld, Katie B Williams, Dana Marafi, Fan Xia, Marta Biderman Waberski, Maha S Zaki, Joseph Gleeson, Erik Puffenberger, Henry Houlden, Reza Maroofian

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Title: Branched-chain α-ketoacid dehydrogenase deficiency (maple syrup urine disease): Treatment, biomarkers, and outcomes Published: March 1, 2020 Publication: Molecular Genetics and Metabolism

Authors: Kevin A. Strauss, Vincent J. Carson, Kyle Soltys, Millie E. Young, Lauren E. Bowser, Erik G. Puffenberger, Karlla W. Brigatti, Katie B. Williams, Donna L. Robinson, Christine Hendrickson, Keturah Beiler, Cora M. Taylor, Barbara Haas-Givler, Stephanie Chopko, Jennifer Hailey, Emilie R. Muelly, Diana A. Shellmer, Zachary Radcliff, Ashlin Rodrigues, KaLynn Loeven, Adam D. Heaps, George V. Mazariegos, D. Holmes Morton

Abstract:
Over the past three decades, we studied 184 individuals with 174 different molecular variants of branched-chain α-ketoacid dehydrogenase activity, and here delineate essential clinical and biochemical aspects of the maple syrup urine disease (MSUD) phenotype. We collected data about treatment, survival, hospitalization, metabolic control, and liver transplantation from patients with classic (i.e., severe; n = 176), intermediate (n = 6) and intermittent (n = 2) forms of MSUD. A total of 13,589 amino acid profiles were used to analyze leucine tolerance, amino acid homeostasis, estimated cerebral amino acid uptake, quantitative responses to anabolic therapy, and metabolic control after liver transplantation. Standard instruments were used to measure neuropsychiatric outcomes. Despite advances in clinical care, classic MSUD remains a morbid and potentially fatal disorder. Stringent dietary therapy maintains metabolic variables within acceptable limits but is challenging to implement, fails to restore appropriate concentration relationships among circulating amino acids, and does not fully prevent cognitive and psychiatric disabilities. Liver transplantation eliminates the need for a prescription diet and safeguards patients from life-threatening metabolic crises, but is associated with predictable morbidities and does not reverse pre-existing neurological sequelae. There is a critical unmet need for safe and effective disease-modifying therapies for MSUD which can be implemented early in life. The biochemistry and physiology of MSUD and its response to liver transplantation afford key insights into the design of new therapies based on gene replacement or editing.
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Title: Spectrum of KV 2.1 Dysfunction in KCNB1-Associated Neurodevelopmental Disorders Published: December 1, 2019 Publication: Annals of Neurology

Authors: Kang SK, Vanoye CG, Misra SN, Echevarria DM, Calhoun JD, O’Connor JB, Fabre KL, McKnight D, Demmer L, Goldenberg P, Grote LE, Tiffault I, Saunders C, Strauss KA, Torkamani A, van der Smagt J, van Gassen K, Carson RP, Diaz J, Leon E, Jacher JE, Hannibal MC, Litwin J, Friedman NR, Schreiber A, Lynch B, Poduri A, Marsh ED, Goldberg EM, Millichap JJ, George AL Jr, Kearney JA

Abstract:
Pathogenic variants in KCNB1, encoding the voltage-gated potassium channel KV 2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression.
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Title: Mass spectrometric quantification of plasma glycosphingolipids in human GM3 ganglioside deficiency Published: November 1, 2019 Publication: Clinical Mass Spectrometry

Authors: Kazuhiro Aoki, Adam D. Heaps, Kevin A. Strauss, Michael Tiemeyer

Abstract:
Among Amish communities of North America, biallelic mutations of ST3GAL5 (c.694C > T) eliminate synthesis of GM3 and its derivative downstream a- and b-series gangliosides. Systemic ganglioside deficiency is associated with infantile onset psychomotor retardation, slow brain growth, intractable epilepsy, deafness, and cortical visual impairment. We developed a robust quantitative assay to simultaneously characterize glycan and ceramide moieties of plasma glycosphingolipids (GSLs) among ST3GAL5 c.694C > T homozygotes (n = 8), their heterozygous siblings (n = 24), and wild type control (n = 19) individuals.
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Title: GATORopathies: The role of amino acid regulatory gene mutations in epilepsy and cortical malformations Published: November 1, 2019 Publication: Epilepsia

Authors: Iffland PH 2nd, Carson V, Bordey A, Crino PB

Abstract:
The mechanistic target of rapamycin (mTOR) pathway has been implicated in a growing number of malformations of cortical development (MCD) associated with intractable epilepsy. Mutations in single genes encoding mTOR pathway regulatory proteins have been linked to MCD such as focal cortical dysplasia (FCD) types IIa and IIb, hemimegalencephaly (HME), and megalencephaly. Recent studies have demonstrated that the GATOR1 protein complex, comprised of DEPDC5, NPRL3, and NPRL2, plays a pivotal role in regulating mTOR signaling in response to cellular amino acid levels and that mutations in DEPDC5, NPRL3, or NPRL2 are linked to FCD, HME, and seizures. Histopathological analysis of FCD and HME tissue specimens resected from individuals harboring DEPDC5, NPRL3, or NPRL2 gene mutations reveals hyperactivation of mTOR pathway signaling. Family pedigrees carrying mutations in either DEPDC5 or NPRL3 share clinical phenotypes of epilepsy and MCD, as well as intellectual and neuropsychiatric disabilities. Interestingly, some individuals with seizures associated with DEPDC5, NPRL3, or NPRL2 variants exhibit normal brain imaging suggesting either occult MCD or a role for these genes in non-lesional neocortical epilepsy. Mouse models resulting from knockdown or knockout of either Depdc5 or Nprl3 exhibit altered cortical lamination, neuronal dysmorphogenesis, and enhanced neuronal excitability as reported in models resulting from direct mTOR activation through expression of its canonical activator RHEB. The role of the GATOR1 proteins in regulating mTOR signaling suggest plausible options for mTOR inhibition in the treatment of epilepsy associated with mutations in DEPDC5, NPRL3, or NPRL2.
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Title: Clinical and genetic validity of quantitative bipolarity Published: September 16, 2019 Publication: Translational Psychiatry

Authors: Bruce HA, Kochunov P, Mitchell B, Strauss KA, Ament SA, Rowland LM, Du X, Fisseha F, Kavita T, Chiappelli J, Wisner K, Sampath H, Chen S, Kvarta MD, Seneviratne C, Postolache TT, Bellon A, McMahon FJ, Shuldiner A, Elliot Hong L

Abstract:
Research has yet to provide a comprehensive understanding of the genetic basis of bipolar disorder (BP). In genetic studies, defining the phenotype by diagnosis may miss risk-allele carriers without BP. The authors aimed to test whether quantitatively detected subclinical symptoms of bipolarity identifies a heritable trait that infers risk for BP. The Quantitative Bipolarity Scale (QBS) was administered to 310 Old Order Amish or Mennonite individuals from multigenerational pedigrees; 110 individuals had psychiatric diagnoses (20 BP, 61 major depressive disorders (MDD), 3 psychotic disorders, 26 other psychiatric disorders). Familial aggregation of QBS was calculated using the variance components method to derive heritability and shared household effects. The QBS score was significantly higher in BP subjects (31.5 ± 3.6) compared to MDD (16.7 ± 2.0), other psychiatric diagnoses (7.0 ± 1.9), and no psychiatric diagnosis (6.0 ± 0.65) (all p < 0.001). QBS in the whole sample was significantly heritable (h2 = 0.46 ± 0.15, p < 0.001) while the variance attributed to the shared household effect was not significant (p = 0.073). When subjects with psychiatric illness were removed, the QBS heritability was similar (h2 = 0.59 ± 0.18, p < 0.001). These findings suggest that quantitative bipolarity as measured by QBS can separate BP from other psychiatric illnesses yet is significantly heritable with and without BP included in the pedigrees suggesting that the quantitative bipolarity describes a continuous heritable trait that is not driven by a discrete psychiatric diagnosis. Bipolarity trait assessment may be used to supplement the diagnosis of BP in future genetic studies and could be especially useful for capturing subclinical genetic contributions to a BP phenotype.
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Title: Development of a Novel Next-Generation Sequencing Assay for Carrier Screening in Old Order Amish and Mennonite Populations of Pennsylvania Published: July 1, 2019 Publication: The Journal of Molecular Diagnostics

Authors: Erin L. Crowgey, Michael C. Washburn, E. Anders Kolb, Erik G. Puffenberger

Abstract:
Genetically isolated populations, such as the Old Order Amish and Old Order Mennonite communities, have an increased incidence of specific autosomal recessive disorders caused by the founder effect. In these populations, robust expanded carrier screening and diagnostic testing have the potential to reduce overall medical costs and improve patient outcomes. A novel next-generation sequencing assay was developed using anchored multiplex PCR technology (ArcherDX) for 162 different genetic syndromes caused by 202 pathogenic variants consisting of 150 single-nucleotide changes, 43 small insertion/deletions, and 9 large deletions (>20 nucleotides). To assess the accuracy of the screening panel results, 48 samples were selected on the basis of prior whole exome sequencing results. An additional 15 samples were chosen specifically to validate SMN1 and SMN2 copy number analyses. Collectively, the screening panel detected 273 pathogenic single-nucleotide or small insertion/deletion variants, 35 copy number variations, and 1 chromosomal abnormality (Klinefelter syndrome). Concordance with prior whole exome sequencing was 100%. By using a novel next-generation sequencing workflow, a successful targeted gene variant panel was developed for the Old Order Amish and Old Order Mennonite populations of Lancaster County, Pennsylvania. Population-wide carrier screening may help decrease the morbidity and mortality of these conditions in the high-risk populations.
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Title: Recessive GM3 synthase deficiency: Natural history, biochemistry, and therapeutic frontier Published: April 1, 2019 Publication: Molecular Genetics and Metabolism

Authors: Bowser LE, Young M, Wenger OK, Ammous Z, Brigatti KW, Carson VJ, Moser T, Deline J, Aoki K, Morlet T, Scott EM, Puffenberger EG, Robinson DL, Hendrickson C, Salvin J, Gottlieb S, Heaps AD, Tiemeyer M, Strauss KA

Abstract:
GM3 synthase, encoded by ST3GAL5, initiates synthesis of all downstream cerebral gangliosides. Here, we present biochemical, functional, and natural history data from 50 individuals homozygous for a pathogenic ST3GAL5 c.862C>T founder allele (median age 8.1, range 0.7-30.5 years). GM3 and its derivatives were undetectable in plasma. Weight and head circumference were normal at birth and mean Apgar scores were 7.7 ± 2.0 (1 min) and 8.9 ± 0.5 (5 min). Somatic growth failure, progressive microcephaly, global developmental delay, visual inattentiveness, and dyskinetic movements developed within a few months of life. Infantile-onset epileptic encephalopathy was characterized by a slow, disorganized, high-voltage background, poor state transitions, absent posterior rhythm, and spike trains from multiple independent cortical foci; >90% of electrographic seizures were clinically silent. Hearing loss affected cochlea and central auditory pathways and 76% of children tested failed the newborn hearing screen. Development stagnated early in life; only 13 (26%) patients sat independently (median age 30 months), three (6%) learned to crawl, and none achieved reciprocal communication. Incessant irritability, often accompanied by insomnia, began during infancy and contributed to high parental stress. Despite catastrophic neurological dysfunction, neuroimaging showed only subtle or no destructive changes into late childhood and hospitalizations were surprisingly rare (0.2 per patient per year). Median survival was 23.5 years. Our observations corroborate findings from transgenic mice which indicate that gangliosides might have a limited role in embryonic neurodevelopment but become vital for postnatal brain growth and function. These results have critical implications for the design and implementation of ganglioside restitution therapies.
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Title: Homozygosity for a mutation affecting the catalytic domain of tyrosyl-tRNA synthetase (YARS) causes multisystem disease Published: February 15, 2019 Publication: Human Molecular Genetics

Authors: Williams KB, Brigatti KW, Puffenberger EG, Gonzaga-Jauregui C, Griffin LB, Martinez ED, Wenger OK, Yoder M, Kandula VVR, Fox MD, Demczko MM, Poskitt L, Furuya KN, Reid JG, Overton JD, Baras A, Miles L, Radhakrishnan K, Carson VJ, Antonellis A, Jinks RN, Strauss KA

Abstract:
Aminoacyl-tRNA synthetases (ARSs) are critical for protein translation. Pathogenic variants of ARSs have been previously associated with peripheral neuropathy and multisystem disease in heterozygotes and homozygotes, respectively. We report seven related children homozygous for a novel mutation in tyrosyl-tRNA synthetase (YARS, c.499C > A, p.Pro167Thr) identified by whole exome sequencing. This variant lies within a highly conserved interface required for protein homodimerization, an essential step in YARS catalytic function. Affected children expressed a more severe phenotype than previously reported, including poor growth, developmental delay, brain dysmyelination, sensorineural hearing loss, nystagmus, progressive cholestatic liver disease, pancreatic insufficiency, hypoglycemia, anemia, intermittent proteinuria, recurrent bloodstream infections and chronic pulmonary disease. Related adults heterozygous for YARS p.Pro167Thr showed no evidence of peripheral neuropathy on electromyography, in contrast to previous reports for other YARS variants. Analysis of YARS p.Pro167Thr in yeast complementation assays revealed a loss-of-function, hypomorphic allele that significantly impaired growth. Recombinant YARS p.Pro167Thr demonstrated normal subcellular localization, but greatly diminished ability to homodimerize in human embryonic kidney cells. This work adds to a rapidly growing body of research emphasizing the importance of ARSs in multisystem disease and significantly expands the allelic and clinical heterogeneity of YARS-associated human disease. A deeper understanding of the role of YARS in human disease may inspire innovative therapies and improve care of affected patients.
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Title: Bi-allelic CCDC47 Variants Cause a Disorder Characterized by Woolly Hair, Liver Dysfunction, Dysmorphic Features, and Global Developmental Delay Published: November 1, 2018 Publication: The American Journal of Human Genetics

Authors: Marie Morimoto, Helen Waller-Evans, Zineb Ammous, Xiaofei Song, Kevin A. Strauss, Davut Pehlivan, Claudia Gonzaga-Jauregui, Erik G. Puffenberger, Charles R. Holst, Ender Karaca, Karlla W. Brigatti, Emily Maguire, Zeynep H. Coban-Akdemir, Akiko Amagata, C. Christopher Lau, Xenia Chepa-Lotrea, Ellen Macnamara, Tulay Tos, Sedat Isikay, Michele Nehrebecky, John D. Overton, Matthew Klein, Thomas C. Markello, Jennifer E. Posey, David R. Adams, Emyr Lloyd-Evans, James R. Lupski, William A. Gahl, May Christine V. Malicdan

Abstract:
Ca2+ signaling is vital for various cellular processes including synaptic vesicle exocytosis, muscle contraction, regulation of secretion, gene transcription, and cellular proliferation. The endoplasmic reticulum (ER) is the largest intracellular Ca2+ store, and dysregulation of ER Ca2+ signaling and homeostasis contributes to the pathogenesis of various complex disorders and Mendelian disease traits. We describe four unrelated individuals with a complex multisystem disorder characterized by woolly hair, liver dysfunction, pruritus, dysmorphic features, hypotonia, and global developmental delay. Through whole-exome sequencing and family-based genomics, we identified bi-allelic variants in CCDC47 that encodes the Ca2+-binding ER transmembrane protein CCDC47. CCDC47, also known as calumin, has been shown to bind Ca2+ with low affinity and high capacity. In mice, loss of Ccdc47 leads to embryonic lethality, suggesting that Ccdc47 is essential for early development. Characterization of cells from individuals with predicted likely damaging alleles showed decreased CCDC47 mRNA expression and protein levels. In vitro cellular experiments showed decreased total ER Ca2+ storage, impaired Ca2+ signaling mediated by the IP3R Ca2+ release channel, and reduced ER Ca2+ refilling via store-operated Ca2+ entry. These results, together with the previously described role of CCDC47 in Ca2+ signaling and development, suggest that bi-allelic loss-of-function variants in CCDC47 underlie the pathogenesis of this multisystem disorder.
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Title: Preliminary safety and tolerability of a novel subcutaneous intrathecal catheter system for repeated outpatient dosing of nusinersen to children and adults with spinal muscular atrophy Published: November 1, 2018 Publication: Journal of Pediatric Orthopaedics

Authors: Kevin A. Strauss, MD, Freeman Miller, MD, Vincent Carson, MD, Karlla W. Brigatti, MS, LCGC, Millie Young, RNC, Donna L. Robinson, CRNP, Christine Hendrickson, RNC, Erik G. Puffenberger, Michael D. Fox, MD, Robert M. Reed, MD, William Mackenzie, MD

Abstract:
Many patients with spinal muscular atrophy (SMA) who might benefit from intrathecal antisense oligonucleotide (nusinersen) therapy have scoliosis or spinal fusion that precludes safe drug delivery. To circumvent spinal pathology, we designed a novel subcutaneous intrathecal catheter (SIC) system by connecting an intrathecal catheter to an implantable infusion port.
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Title: TNNT1 nemaline myopathy: natural history and therapeutic frontier. Published: September 15, 2018 Publication: Human Molecular Genetics

Authors: Michael D. Fox, Vincent J. Carson, Han-Zhong Feng, Michael W. Lawlor, John T. Gray, Karlla W. Brigatti, J.-P. Jin, Kevin A. Strauss

Abstract:
We describe the natural history of 'Amish' nemaline myopathy (ANM), an infantile-onset, lethal disease linked to a pathogenic c.505G>T nonsense mutation of TNNT1, which encodes the slow fiber isoform of troponin T (TNNT1; a.k.a. TnT). The TNNT1 c.505G>T allele has a carrier frequency of 6.5% within Old Order Amish settlements of North America. We collected natural history data for 106 ANM patients born between 1923 and 2017. Over the last two decades, mean age of molecular diagnosis was 16 ± 27 days. TNNT1 c.505G>T homozygotes were normal weight at birth but failed to thrive by age 9 months. Presenting neonatal signs were axial hypotonia, hip and shoulder stiffness, and tremors, followed by progressive muscle weakness, atrophy and contractures. Affected children developed thoracic rigidity, pectus carinatum and restrictive lung disease during infancy, and all succumbed to respiratory failure by 6 years of age (median survival 18 months, range 0.2-66 months). Muscle histology from two affected children showed marked fiber size variation owing to both Type 1 myofiber smallness (hypotrophy) and Type 2 fiber hypertrophy, with evidence of nemaline rods, myofibrillar disarray and vacuolar pathology in both fiber types. The truncated slow TNNT1 (TnT) fragment (p.Glu180Ter) was undetectable in ANM muscle, reflecting its rapid proteolysis and clearance from sarcoplasm. Similar functional and histological phenotypes were observed in other human cohorts and two transgenic murine models (Tnnt1-/- and Tnnt1 c.505G>T). These findings have implications for emerging molecular therapies, including the suitably of TNNT1 gene replacement for newborns with ANM or other TNNT1-associated myopathies.
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Title: Spinal muscular atrophy within Amish and Mennonite populations: Ancestral haplotypes and natural history Published: September 6, 2018 Publication: PLOS One

Authors: Carson VJ, Puffenberger EG, Bowser LE, Brigatti KW, Young M, Korulczyk D, Rodrigues AS, Loeven KK, Strauss KA

Abstract:
We correlate chromosome 5 haplotypes and SMN2 copy number with disease expression in 42 Mennonite and 14 Amish patients with spinal muscular atrophy (SMA). A single haplotype (A1) with 1 copy of SMN2 segregated among all Amish patients. SMN1 deletions segregated on four different Mennonite haplotypes that carried 1 (M1a, M1b, M1c) or 2 (M2) copies of SMN2. DNA microsatellite and microarray data revealed structural similarities among A1, M1a, M1b, and M2. Clinical data were parsed according to both SMN1 genotype and SMN2 copy number (2 copies, n = 44; 3 copies, n = 9; or 4 copies, n = 3). No infant with 2 copies of SMN2 sat unassisted. In contrast, all 9 Mennonites with the M1a/M2 genotype (3 copies of SMN2) sat during infancy at a median age of 7 months, and 5 (56%) walked and dressed independently at median ages of 18 and 36 months, respectively. All are alive at a median age of 11 (range 2-31) years without ventilatory support. Among 13 Amish and 26 Mennonite patients with 2 copies of SMN2 who did not receive feeding or ventilatory support, A1/A1 as compared to M1a/M1a genotype was associated with earlier clinical onset (p = 0.0040) and shorter lifespan (median survival 3.9 versus 5.7 months, p = 0.0314). These phenotypic differences were not explained by variation in SMN1 deletion size or SMN2 coding sequence, which were conserved across haplotypes. Distinctive features of SMA within Plain communities provide a population-specific framework to study variations of disease expression and the impact of disease-modifying therapies administered early in life.
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Title: 233rd ENMC International Workshop: Clinical Trial Readiness for Calpainopathies, Naarden, The Netherlands, 15-17 September 2017 Published: June 1, 2018 Publication: Neuromuscular Disorders

Authors: William Lostal, J. Andoni Urtizberea, Isabelle Richard, the calpain 3 study group

Abstract:
Eighteen researchers and clinicians and two representatives of patient organizations (Associazione Italiana Calpaina 3, Italy and Coalition to Cure Calpain3, USA), from 9 countries (France, Germany, Italy, Denmark, Spain, UK, Japan, Brazil and USA), met in Naarden, The Netherlands, from 15–17 September, 2017 to discuss clinical trial readiness for limb-girdle muscular dystrophy type 2A (LGMD2A; OMIM 253600), also classically referred to as calpainopathy. LGMD2A is due to mutations in the CAPN3 gene encoding a calcium-dependent cysteine protease named calpain 3 [[1]]. This disease is characterized by slowly progressive muscle weakness affecting selectively the musculature of both girdles. There is no effective treatment for this disease to date. The emergence of novel therapeutic approaches in the field, such as gene therapy, has prompted a much awaited discussion among physicians and researchers about the readiness for clinical trials in calpainopathy.
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Title: Monoallelic BMP2 Variants Predicted to Result in Haploinsufficiency Cause Craniofacial, Skeletal, and Cardiac Features Overlapping Those of 20p12 Deletions Published: December 7, 2017 Publication: The American Journal of Human Genetics

Authors: Yang Tan T, Gonzaga-Jauregui C, Bhoj EJ, Strauss KA, Brigatti KW, Puffenberger E, Li D, Xie L, Das N, Skubas I, Deckelbaum RA, Hughes V, Brydges S, Hatsell S, Siao C, Dominguez MG, Economides A, Overton JD, Mayne V, Simm PJ, Jones BO, Eggers S, Le Guyader G, Pelluard F, Haack TB, Sturm M, Riess A, Waldmueller S, Hofbeck M, Steindl K, Joset P, Rauch A, Hakonarson H, Baker NL, Farlie PG

Abstract:
Bone morphogenetic protein 2 (BMP2) in chromosomal region 20p12 belongs to a gene superfamily encoding TGF-β-signaling proteins involved in bone and cartilage biology. Monoallelic deletions of 20p12 are variably associated with cleft palate, short stature, and developmental delay. Here, we report a cranioskeletal phenotype due to monoallelic truncating and frameshift BMP2 variants and deletions in 12 individuals from eight unrelated families that share features of short stature, a recognizable craniofacial gestalt, skeletal anomalies, and congenital heart disease. De novo occurrence and autosomal-dominant inheritance of variants, including paternal mosaicism in two affected sisters who inherited a BMP2 splice-altering variant, were observed across all reported families. Additionally, we observed similarity to the human phenotype of short stature and skeletal anomalies in a heterozygous Bmp2-knockout mouse model, suggesting that haploinsufficiency of BMP2 could be the primary phenotypic determinant in individuals with predicted truncating variants and deletions encompassing BMP2. These findings demonstrate the important role of BMP2 in human craniofacial, skeletal, and cardiac development and confirm that individuals heterozygous for BMP2 truncating sequence variants or deletions display a consistent distinct phenotype characterized by short stature and skeletal and cardiac anomalies without neurological deficits.
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Title: Management of Congenital Health Disease Associated with Ellis-van Creveld Short-rib Thoracic Dysplasia Published: December 1, 2017 Publication: The Journal of Pediatrics

Authors: Chowdhury D, Williams KB, Chidekel A, Pizarro C, Preedy C, Young M, Hendrickson C, Robinson DL, Kreiger P, Puffenberger EG, Strauss KA

Abstract:
To evaluate clinical outcome of patients with Ellis-van Creveld syndrome (EVC) in whom congenital heart disease (CHD) repair was delayed intentionally to reduce the risk of postoperative respiratory morbidity and mortality.
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Title: Defects in lymphocyte telomere homeostasis contribute to cellular immune phenotype in patients with cartilage-hair hypoplasia Published: October 1, 2017 Publication: Journal of Allergy and Clinical Immunology

Authors: Aubert G, Strauss KA, Lansdorp PM, Rider NL

Abstract:
Mutations in the long noncoding RNA RNase component of the mitochondrial RNA processing endoribonuclease (RMRP) give rise to the autosomal recessive condition cartilage-hair hypoplasia (CHH). The CHH disease phenotype has some overlap with dyskeratosis congenita, a well-known "telomere disorder." RMRP binds the telomerase reverse transcriptase (catalytic subunit) in some cell lines, raising the possibility that RMRP might play a role in telomere biology.
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Title: Genomic diagnostics within a medically underserved population: efficacy and implications Published: July 20, 2017 Publication: Genetics in Medicine

Authors: Strauss KA, Gonzaga-Jauregui C, Brigatti KW, Williams KB, King AK, Van Hout C, Robinson DL, Young M, Praveen K, Heaps AD, Kuebler M, Baras A, Reid JG, Overton JD, Dewey FE, Jinks RN, Finnegan I, Mellis SJ, Shuldiner AR, Puffenberger EG

Abstract:
We integrated whole-exome sequencing (WES) and chromosomal microarray analysis (CMA) into a clinical workflow to serve an endogamous, uninsured, agrarian community.
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Title: Gangliosides and Hearing Published: May 30, 2017 Publication: BBA - General Subjects

Authors: Inokuchi JI, Go S, Yoshikawa M, Strauss K

Abstract:
Severe auditory impairment observed in GM3 synthase-deficient mice and humans indicates that glycosphingolipids, especially sialic-acid containing gangliosides, are indispensable for hearing. Gangliosides associate with glycoproteins to form membrane microdomains, the composition of which plays a special role in maintaining the structural and functional integrity of hair cells. These microdomains, also called lipid rafts, connect with intracellular signaling and cytoskeletal systems to link cellular responses to environmental cues. During development, ganglioside species are expressed in distinctive spatial and temporal patterns throughout the cochlea. In both mice and humans, blocking particular steps of ganglioside metabolism produces distinctive neurological and auditory phenotypes. Thus each ganglioside species may have specific, non-overlapping functions within the cochlea, central auditory network, and brain.
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Title: Mutations in CRADD Result in Reduced Caspase-2-Mediated Neuronal Apoptosis and Cause Megalencephaly with a Rare Lissencephaly Variant Published: November 3, 2016 Publication: The American Journal of Human Genetics

Authors: Di Donato N, Jean YY, Maga AM, Krewson BD, Shupp AB, Avrutsky MI, Roy A, Collins S, Olds C, Willert RA, Czaja AM, Johnson R, Stover, JA, Gottlieb S, Bartholdi D, Rauch A, Goldstein A, Boyd-Kyle V, Aldinger KA, Mirzaa GM, Nissen A, Brigatti KW, Puffenberger EG, Millen KJ, Strauss KA, Dobyns WB, Troy CM, Jinks RN

Abstract:
Lissencephaly is a malformation of cortical development typically caused by deficient neuronal migration resulting in cortical thickening and reduced gyration. Here we describe a "thin" lissencephaly (TLIS) variant characterized by megalencephaly, frontal predominant pachygyria, intellectual disability, and seizures. Trio-based whole-exome sequencing and targeted re-sequencing identified recessive mutations of CRADD in six individuals with TLIS from four unrelated families of diverse ethnic backgrounds. CRADD (also known as RAIDD) is a death-domain-containing adaptor protein that oligomerizes with PIDD and caspase-2 to initiate apoptosis. TLIS variants cluster in the CRADD death domain, a platform for interaction with other death-domain-containing proteins including PIDD. Although caspase-2 is expressed in the developing mammalian brain, little is known about its role in cortical development. CRADD/caspase-2 signaling is implicated in neurotrophic factor withdrawal- and amyloid-β-induced dendritic spine collapse and neuronal apoptosis, suggesting a role in cortical sculpting and plasticity. TLIS-associated CRADD variants do not disrupt interactions with caspase-2 or PIDD in co-immunoprecipitation assays, but still abolish CRADD's ability to activate caspase-2, resulting in reduced neuronal apoptosis in vitro. Homozygous Cradd knockout mice display megalencephaly and seizures without obvious defects in cortical lamination, supporting a role for CRADD/caspase-2 signaling in mammalian brain development. Megalencephaly and lissencephaly associated with defective programmed cell death from loss of CRADD function in humans implicate reduced apoptosis as an important pathophysiological mechanism of cortical malformation. Our data suggest that CRADD/caspase-2 signaling is critical for normal gyration of the developing human neocortex and for normal cognitive ability.
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Title: A critical reappraisal of dietary practices in methylmalonic acidemia raises concerns about the safety of medical foods. Part 2: cobalamin C deficiency Published: April 1, 2016 Publication: Genetics in Medicine

Authors: Manoli I, Myles JG, Sloan JL, Carrillo-Carrasco N, Morava E, Strauss KA, Morton H, Venditti CP

Abstract:
Cobalamin C (cblC) deficiency impairs the biosynthesis of 5'-deoxyadenosyl-adenosyl- and methyl-cobalamin, resulting in methylmalonic acidemia combined with hyperhomocysteinemia and hypomethioninemia. However, some patients with cblC deficiency are treated with medical foods, devoid of methionine and high in leucine content, that are formulated for patients with isolated propionate oxidative defects. We examined the effects of imbalanced branched-chain amino acid intake on growth outcomes in cblC-deficient patients.
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Title: Abnormal Hypermethylation at Imprinting Control Regions in Patients with S-Adenosylhomocysteine Hydrolase (AHCY) Deficiency. Published: March 14, 2016 Publication: PLOS One

Authors: Motzek A, Knezevic J, Switzeny OJ, Cooper A, Baric I, Beluzic R, Strauss KA, Puffenberger EG, Mudd SH, Vugrek O, Zechner U

Abstract:
S-adenosylhomocysteine hydrolase (AHCY) deficiency is a rare autosomal recessive disorder in methionine metabolism caused by mutations in the AHCY gene. Main characteristics are psychomotor delay including delayed myelination and myopathy (hypotonia, absent tendon reflexes etc.) from birth, mostly associated with hypermethioninaemia, elevated serum creatine kinase levels and increased genome wide DNA methylation. The prime function of AHCY is to hydrolyse and efficiently remove S-adenosylhomocysteine, the by-product of transmethylation reactions and one of the most potent methyltransferase inhibitors. In this study, we set out to more specifically characterize DNA methylation changes in blood samples from patients with AHCY deficiency. Global DNA methylation was increased in two of three analysed patients. In addition, we analysed the DNA methylation levels at differentially methylated regions (DMRs) of six imprinted genes (MEST, SNRPN, LIT1, H19, GTL2 and PEG3) as well as Alu and LINE1 repetitive elements in seven patients. Three patients showed a hypermethylation in up to five imprinted gene DMRs. Abnormal methylation in Alu and LINE1 repetitive elements was not observed. We conclude that DNA hypermethylation seems to be a frequent but not a constant feature associated with AHCY deficiency that affects different genomic regions to different degrees. Thus AHCY deficiency may represent an ideal model disease for studying the molecular origins and biological consequences of DNA hypermethylation due to impaired cellular methylation status.
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Title: Living related versus deceased donor liver transplantation for maple syrup urine disease Published: March 1, 2016 Publication: Molecular Genetics and Metabolism

Authors: Feier F, Schwartz IV, Benkert AR, Neto JS, Miura I, Chapchap P, da Fonseca EA, Vieira S, Zanotelli ML, Vairo FP, Camelo JS Jr, Margutti AV, Mazariegos GV, Puffenberger EG, Strauss KA

Abstract:
Maple syrup urine disease (MSUD) is an inherited disorder of branched chain ketoacid (BCKA) oxidation associated with episodic and chronic brain disease. Transplantation of liver from an unrelated deceased donor restores 9-13% whole-body BCKA oxidation capacity and stabilizes MSUD. Recent reports document encouraging short-term outcomes for MSUD patients who received a liver segment from mutation heterozygous living related donors (LRDT). To investigate effects of living related versus deceased unrelated grafts, we studied four Brazilian MSUD patients treated with LRDT who were followed for a mean 19 ± 12 postoperative months, and compared metabolic and clinical outcomes to 37 classical MSUD patients treated with deceased donor transplant. Patient and graft survival for LRDT were 100%. Three of 4 MSUD livers were successfully domino transplanted into non-MSUD subjects. Following LRDT, all subjects resumed a protein-unrestricted diet as mean plasma leucine decreased from 224 ± 306 μM to 143 ± 44 μM and allo-isoleucine decreased 91%. We observed no episodes of hyperleucinemia during 80 aggregate postoperative patient-months. Mean plasma leucine:isoleucine:valine concentration ratios were ~2:1:4 after deceased donor transplant compared to ~1:1:1.5 following LRDT, resulting in differences of predicted cerebral amino acid uptake. Mutant heterozygous liver segments effectively maintain steady-state BCAA and BCKA homeostasis on an unrestricted diet and during most catabolic states, but might have different metabolic effects than grafts from unrelated deceased donors. Neither living related nor deceased donor transplant affords complete protection from metabolic intoxication, but both strategies represent viable alternatives to nutritional management.
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Title: Heritability of complex white matter diffusion traits assessed in a population isolate Published: February 1, 2016 Publication: Human Brain Mapping

Authors: Kochunov P, Fu M, Nugent K, Wright SN, Du X, Muellerklein F, Morrissey M, Eskandar G, Shukla DK, Jahanshad N, Thompson PM, Patel B, Postolache TT, Strauss KA, Shuldiner AR, Mitchell BD, Hong LE

Abstract:
Diffusion weighted imaging (DWI) methods can noninvasively ascertain cerebral microstructure by examining pattern and directions of water diffusion in the brain. We calculated heritability for DWI parameters in cerebral white (WM) and gray matter (GM) to study the genetic contribution to the diffusion signals across tissue boundaries.
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Title: Liver transplantation for treatment of severe S-adenosylhomocysteine hydrolase deficiency Published: September 1, 2015 Publication: Molecular Genetics and Metabolism

Authors: Strauss KA, Ferreira C, Bottiglieri T, Zhao X, Arning E, Zhang S, Zeisel SH, Escolar ML, Presnick N, Puffenberger EG, Vugrek O, Kovacevic L, Wagner C, Mazariegos GV, Mudd SH, Soltys K

Abstract:
A child with severe S-adenosylhomocysteine hydrolase (AHCY) deficiency (AHCY c.428A N G, p.Tyr143Cys; c.982 T N G, p.Tyr328Asp) presented at 8 months of age with growth failure, microcephaly, global developmental delay, myopathy, hepatopathy, and factor VII deficiency. Plasma methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) were markedly elevated and the molar concentration ratio of AdoMet:AdoHcy, believed to regulate a myriad of methyltransferase reactions, was 15% of the control mean. Dietary therapy failed to normalize biochemical markers or alter the AdoMet to AdoHcy molar concentration ratio. At 40 months of age, the proband received a liver segment from a healthy, unrelated living donor. Mean AdoHcy decreased 96% and the AdoMet:AdoHcy concentration ratio improved from 0.52 ± 0.19 to 1.48 ± 0.79 mol:mol (control 4.10 ± 2.11 mol:mol). Blood methionine and AdoMet were normal and stable during 6 months of follow-up on an unrestricted diet. Average calculated tissue methyltransferase activity increased from 43 ± 26% to 60 ± 22%, accompanied by signs of increased transmethylation in vivo. Factor VII activity increased from 12% to 100%. During 6 postoperative months, head growth accelerated 4-fold and the patient made promising gains in gross motor, language, and social skills.
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Title: Recessive nephrocerebellar syndrome on the Galloway-Mowat syndrome spectrum is caused by homozygous protein-truncating mutations of WDR73 Published: August 1, 2015 Publication: Brain

Authors: Jinks RN, Puffenberger EG, Baple E, Harding B, Crino P, Fogo AB, Wenger O, Xin B, Koehler AE, McGlincy MH, Provencher MM, Smith JD, Tran L, Al Turki S, Chioza BA, Cross H, Harlalka GV, Hurles ME, Maroofian R, Heaps AD, Morton MC, Stempak L, Hildebrandt F, Sadowski CE, Zaritsky J, Campellone K, Morton DH, Wang H, Crosby A, Strauss KA

Abstract:
We describe a novel nephrocerebellar syndrome on the Galloway-Mowat syndrome spectrum among 30 children (ages 1.0 to 28years) from diverse Amish demes. Children with nephrocerebellar syndrome had progressive microcephaly, visual impairment,stagnant psychomotor development, abnormal extrapyramidal movements and nephrosis. Fourteen died between ages 2.7 and 28years, typically from renal failure. Post-mortem studies revealed (i) micrencephaly without polymicrogyria or heterotopia;(ii) atrophic cerebellar hemispheres with stunted folia, profound granule cell depletion, Bergmann gliosis, and signs of Purkinjecell deafferentation; (iii) selective striatal cholinergic interneuron loss; and (iv) optic atrophy with delamination of the lateralgeniculate nuclei. Renal tissue showed focal and segmental glomerulosclerosis and extensive effacement and microvillus transformation of podocyte foot processes. Nephrocerebellar syndrome mapped to 700 kb on chromosome 15, which contained a singlenovel homozygous frameshift variant (WDR73 c.888delT; p.Phe296Leufs*26). WDR73 protein is expressed in human cerebralcortex, hippocampus, and cultured embryonic kidney cells. It is concentrated at mitotic microtubules and interacts with a-, b-, and-tubulin, heat shock proteins 70 and 90 (HSP-70; HSP-90), and the carbamoyl phosphate synthetase 2/aspartate transcarbamylase/dihydroorotase multi-enzyme complex. Recombinant WDR73 p.Phe296Leufs*26 and p.Arg256Profs*18 proteins are truncated, unstable, and show increased interaction with a- and b-tubulin and HSP-70/HSP-90. Fibroblasts from patients homozygousfor WDR73 p.Phe296Leufs*26 proliferate poorly in primary culture and senesce early. Our data suggest that in humans, WDR73interacts with mitotic microtubules to regulate cell cycle progression, proliferation and survival in brain and kidney. We extend theGalloway-Mowat syndrome spectrum with the first description of diencephalic and striatal neuropathology.
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Title: Fractures on bisphosphonates in osteoporosis pseudoglioma syndrome (OPPG): pQCT shows poor bone density and structure. Published: August 1, 2015 Publication: Bone

Authors: Streeten EA, Ramirez S, Eliades M, Jaimungal S, Chandrasekaran S, Kathleen R, Morton DH, Puffenberger EG, Herskovitz R, Leonard MB

Abstract:
Osteoporosis pseudoglioma syndrome (OPPG) is a rare autosomal recessive disorder of childhood osteoporosis and blindness due to inactivating mutations in LDL receptor-like protein 5 (LRP5). We and others have reported improvement in areal bone mineral density (aBMD) by DXA in OPPG on short term bisphosphonates. Long-term data on bisphosphonate use in OPPG and measures of volumetric BMD (vBMD) and cortical structure are not available. In addition, no long-term DXA data on untreated OPPG is available. The aims of this study were to: (1) record low trauma fractures and longitudinal aBMD by DXA in 5 OPPG patients on chronic bisphosphonate treatment, and in 4 OPPG patients never treated (2) to perform tibia peripheral quantitative CT (pQCT) to evaluate volumetric bone mineral density (vBMD), cortical structure and calf muscle area in 6 OPPG patients and 14 unaffected first degree family members. pQCT results were converted to sex-specific Z-scores for age and adjusted for tibia length based on data in >700 reference participants. We observed 4 fractures (3 femoral shafts) in 3 OPPG patients while on bisphosphonates, after each achieved significant improvement in aBMD. OPPG participants had significantly lower mean trabecular vBMD (-1.51 vs. 0.17, p = 0.002), cortical area (-2.36 vs. 0.37; p < 0.001) and periosteal circumference (-1.86 vs. -0.31, p = 0.001) Z-scores, compared with unaffected participants and had a trend toward lower muscle area Z-score (-0.69 vs. 0.47, p = 0.12). These data demonstrate substantial bone fragility despite improvements in aBMD. The pQCT data provide insight into the fragility with substantial deficits in trabecular vBMD and cortical dimensions, consistent with OPPG effects of bone formation. Treatment that improves bone quality is needed to reduce fractures in OPPG.
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Title: Mutations in DDX3X Are a Common Cause of Unexplained Intellectual Disability with Gender-Specific Effects on Wnt Signaling Published: July 28, 2015 Publication: The American Journal of Human Genetics

Authors: Snijders Blok L, Madsen E, Juusola J, Gilissen C, Baralle D, Reijnders MR, Venselaar H, Helsmoortel C, Cho MT, Hoischen A, Vissers LE, Koemans TS, Wissink-Lindhout W, Eichler EE, Romano C, Van Esch H, Stumpel C, Vreeburg M, Smeets E, Oberndorff K, van Bon BW, Shaw M, Gecz J, Haan E, Bienek M, Jensen C, Loeys BL, Van Dijck A, Innes AM, Racher H, Vermeer S, Di Donato N, Rump A, Tatton-Brown K, Parker MJ, Henderson A, Lynch SA, Fryer A, Ross A, Vasudevan P, Kini U, Newbury-Ecob R, Chandler K, Male A; DDD Study, Dijkstra S, Schieving J, Giltay J, van Gassen KL, Schuurs-Hoeijmakers J, Tan PL, Pediaditakis I, Haas SA, Retterer K, Reed P, Monaghan KG, Haverfield E, Natowicz M, Myers A, Kruer MC, Stein Q, Strauss KA, Brigatti KW, Keating K, Burton BK, Kim KH, Charrow J, Norman J, Foster-Barber A, Kline AD, Kimball A, Zackai E, Harr M, Fox J, McLaughlin J, Lindstrom K, Haude KM, van Roozendaal K, Brunner H, Chung WK, Kooy RF, Pfundt R, Kalscheuer V, Mehta SG, Katsanis N, Kleefstra T

Abstract:
Intellectual disability (ID) affects approximately 1%–3% of humans with a gender bias toward males. Previous studies have identifiedmutations in more than 100 genes on the X chromosome in males with ID, but there is less evidence for de novo mutations on theX chromosome causing ID in females. In this study we present 35 unique deleterious de novo mutations in DDX3X identified by wholeexome sequencing in 38 females with ID and various other features including hypotonia, movement disorders, behavior problems,corpus callosum hypoplasia, and epilepsy. Based on our findings, mutations in DDX3X are one of the more common causes of ID,accounting for 1%–3% of unexplained ID in females. Although no de novo DDX3X mutations were identified in males, we present threefamilies with segregating missense mutations in DDX3X, suggestive of an X-linked recessive inheritance pattern. In these families, allmales with the DDX3X variant had ID, whereas carrier females were unaffected. To explore the pathogenic mechanisms accountingfor the differences in disease transmission and phenotype between affected females and affected males with DDX3X missense variants,we used canonical Wnt defects in zebrafish as a surrogate measure of DDX3X function in vivo. We demonstrate a consistent loss-of-function effect of all tested de novo mutations on the Wnt pathway, and we further show a differential effect by gender. The differentialactivity possibly reflects a dose-dependent effect of DDX3X expression in the context of functional mosaic females versus one-copymales, which reflects the complex biological nature of DDX3X mutations.
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Title: Development of DNA Confirmatory and High-Risk Diagnostic Testing for Newborns Using Targeted Next-Generation DNA Sequencing Published: May 1, 2015 Publication: Genetics in Medicine

Authors: Bhattacharjee, A, Sokolsky, T, Wyman, SK, Reese, MG, Puffenberger, EG, Strauss, KA, Morton, DH, Parad, RB, Naylor, EW

Abstract:
Genetic testing is routinely used for second-tier confirmation of newborn sequencing results to rule out false positives and to confirm diagnoses in newborns undergoing inpatient and outpatient care. We developed a targeted next-generation sequencing panel coupled with a variant processing pipeline and demonstrated utility and performance benchmarks across multiple newborn disease presentations in a retrospective clinical study.
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Title: Ganglioside GM3 is essential for the structural integrity and function of cochlear hair cells Published: March 5, 2015 Publication: Human Molecular Genetics

Authors: Yoshikawa M, Go S, Suzuki S, Suzuki A, Katori Y, Morlet T, Gottlieb SM, Fujiwara M, Iwasaki K, Strauss KA, Inokuchi J

Abstract:
GM3 synthase (ST3GAL5) is the first biosynthetic enzyme of a- and b-series gangliosides. Patients with GM3 synthase deficiency suffer severe neurological disability and deafness. Eight children (ages 4.1 ± 2.3 years) homozygous for ST3GAL5 c.694C>T had no detectable GM3 (a-series) or GD3 (b-series) in plasma. Their auditory function was characterized by the absence of middle ear muscle reflexes, distortion product otoacoustic emissions and cochlear microphonics, as well as abnormal auditory brainstem responses and cortical auditory-evoked potentials. In St3gal5−/−mice, stereocilia of outer hair cells showed signs of degeneration as early as postnatal Day 3 (P3); thereafter, blebs devoid of actin or tubulin appeared at the region of vestigial kinocilia, suggesting impaired vesicular trafficking. Stereocilia of St3gal5−/− inner hair cells were fused by P17, and protein tyrosine phosphatase receptor Q, normally linked to myosin VI at the tapered base of stereocilia, was maldistributed along the cell membrane. B4galnt1−/− (GM2 synthase-deficient) mice expressing only GM3 and GD3 gangliosides had normal auditory structure and function. Thus, GM3-dependent membrane microdomains might be essential for the proper organization and maintenance of stereocilia in auditory hair cells.
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Title: Cartilage hair hypoplasia: characteristics and orthopaedic manifestations Published: February 27, 2015 Publication: Journal of Children's Orthopaedics

Authors: Riley P, Weiner DS, Leighley B, Jonah D, Morton DH, Strauss KA, Bober MB, Dicintio MS

Abstract:
Cartilage hair hypoplasia (CHH) is a rare metaphyseal chondrodysplasia characterized by short stature and short limbs, found primarily in Amish and Finnish populations. Cartilage hair hypoplasia is caused by mutations in the RMRP gene located on chromosome 9p13.3. The disorder has several characteristic orthopaedic manifestations, including joint laxity, limited elbow extension, ankle varus, and genu varum. Immunodeficiency is of concern in most cases. Although patients exhibit orthopaedic problems, the orthopaedic literature on CHH patients is scant at best. The objective of this study was to characterize the orthopaedic manifestations of CHH based on the authors’ unique access to the largest collection of CHH patients ever reported.
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Title: CODAS Syndrome Is Associated with Mutations of LONP1, Encoding Mitochondrial AAA+ Lon Protease Published: January 8, 2015 Publication: The American Journal of Human Genetics

Authors: Strauss KA, Jinks RN, Puffenberger EG, Venkatesh S, Singh K, Cheng I, Mikita N, Thilagavathi J, Lee J, Sarafianos S, Benkert A, Koehler A, Zhu A, Trovillion V, McGlincy M, Morlet T, Deardorff M, Innes AM, Prasad C, Chudley AE, Lee INW, Suzuki CK

Abstract:
CODAS syndrome is a multi-system developmental disorder characterized by cerebral, ocular, dental, auricular, and skeletal anomalies. Using whole-exome and Sanger sequencing, we identified four LONP1 mutations inherited as homozygous or compound-heterozygous combinations among ten individuals with CODAS syndrome. The individuals come from three different ancestral backgrounds (AmishSwiss from United States, n ¼ 8; Mennonite-German from Canada, n ¼ 1; mixed European from Canada, n ¼ 1). LONP1 encodes Lon protease, a homohexameric enzyme that mediates protein quality control, respiratory-complex assembly, gene expression, and stress responses in mitochondria. All four pathogenic amino acid substitutions cluster within the AAAþ domain at residues near the ATP-binding pocket. In biochemical assays, pathogenic Lon proteins show substrate-specific defects in ATP-dependent proteolysis. When expressed recombinantly in cells, all altered Lon proteins localize to mitochondria. The Old Order Amish Lon variant (LONP1 c.2161C>G[p.Arg721Gly]) homo-oligomerizes poorly in vitro. Lymphoblastoid cell lines generated from affected children have (1) swollen mitochondria with electron-dense inclusions and abnormal inner-membrane morphology; (2) aggregated MT-CO2, the mtDNA-encoded subunit II of cytochrome c oxidase; and (3) reduced spare respiratory capacity, leading to impaired mitochondrial proteostasis and function. CODAS syndrome is a distinct, autosomal-recessive, developmental disorder associated with dysfunction of the mitochondrial Lon protease.
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Title: A population-based study of KCNH7 p.Arg394His and bipolar spectrum disorder Published: July 15, 2014 Publication: Human Molecular Genetics

Authors: Strauss KA, Markx S, Georgi B, Paul SM, Jinks RN, Hoshi T, McDonald A, First MB, Liu W, Benkert AR, Heaps AD, Tian Y, Chakravarti A, Bucan M, Puffenberger EG

Abstract:
We conducted blinded psychiatric assessments of 26 Amish subjects (52+11 years) from four families with prevalent bipolar spectrum disorder, identified 10 potentially pathogenic alleles by exome sequencing, tested association of these alleles with clinical diagnoses in the larger Amish Study of Major Affective Disorder (ASMAD) cohort, and studied mutant potassium channels in neurons. Fourteen of 26 Amish had bipolar spectrum disorder. The only candidate allele shared among them was rs78247304, a non-synonymous variant of KCNH7 (c.1181G>A, p.Arg394His). KCNH7 c.1181G>A and nine other potentially pathogenic variants were subsequently tested within the ASMAD cohort, which consisted of 340 subjects grouped into controls subjects and affected subjects from overlapping clinical categories (bipolar 1 disorder, bipolar spectrum disorder and any major affective disorder). KCNH7 c.1181G>A had the highest enrichment among individuals with bipolar spectrum disorder (x2 5 7.3) and the strongest family-based association with bipolar 1 (P 5 0.021), bipolar spectrum (P 5 0.031) and any major affective disorder (P 5 0.016). In vitro, the p.Arg394His substitution allowed normal expression, trafficking, assembly and localization of HERG3/Kv11.3 channels, but altered the steady-state voltage dependence and kinetics of activation in neuronal cells. Although our genome-wide statistical results do not alone prove association, cumulative evidence from multiple independent sources (parallel genome-wide study cohorts, pharmacological studies of HERG-type potassium channels, electrophysiological data) implicates neuronal HERG3/Kv11.3 potassium channels in the pathophysiology of bipolar spectrum disorder. Such a finding, if corroborated by future studies, has implications for mental health services among the Amish, as well as development of drugs that specifically target HERG3/Kv11.3.
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Title: Dopamine transporter deficiency syndrome: phenotypic spectrum from infancy to adulthood Published: April 1, 2014 Publication: Brain

Authors: Ng J, Zhen J, Meyer E, Erreger K, Li Y, Kakar N, Ahmad J, Thiele H, Kubisch C, Rider NL, Morton DH, Strauss KA, Puffenberger EG, D’Agnano D, Anikster Y, Carducci C, Hyland K, Rotstein M, Leuzzi V, Borck G, Reith ME, Kurian MA

Abstract:
Dopamine transporter deficiency syndrome due to SLC6A3 mutations is the first inherited dopamine ‘transportopathy’ to be described, with a classical presentation of early infantile-onset progressive parkinsonism dystonia. In this study we have identified a new cohort of patients with dopamine transporter deficiency syndrome, including, most significantly, atypical presentation later in childhood with a milder disease course. We report the detailed clinical features, molecular genetic findings and in vitro functional investigations undertaken for adult and paediatric cases. Patients presenting with parkinsonism dystonia or a neurotransmitter profile characteristic of dopamine transporter deficiency syndrome were recruited for study. SLC6A3 mutational analysis was undertaken in all patients. The functional consequences of missense variants on the dopamine transporter were evaluated by determining the effect of mutant dopamine transporter on dopamine uptake, protein expression and amphetamine-mediated dopamine efflux using an in vitro cellular heterologous expression system. We identified eight new patients from five unrelated families with dopamine transporter deficiency syndrome. The median age at diagnosis was 13 years (range 1.5–34 years). Most significantly, the case series included three adolescent males with atypical dopamine transporter deficiency syndrome of juvenile onset (outside infancy) and progressive parkinsonism dystonia. The other five patients in the cohort presented with classical infantile-onset parkinsonism dystonia, with one surviving into adulthood (currently aged 34 years) and labelled as having ‘juvenile parkinsonism’. All eight patients harboured homozygous or compound heterozygous mutations in SLC6A3, of which the majority are previously unreported variants. In vitro studies of mutant dopamine transporter demonstrated multifaceted loss of dopamine transporter function. Impaired dopamine uptake was universally present, and more severely impacted in dopamine transporter mutants causing infantile-onset rather than juvenile-onset disease. Dopamine transporter mutants also showed diminished dopamine binding affinity, reduced cell surface transporter, loss of post-translational dopamine transporter glycosylation and failure of amphetamine-mediated dopamine efflux. Our data series expands the clinical phenotypic continuum of dopamine transporter deficiency syndrome and indicates that there is a phenotypic spectrum from infancy (early onset, rapidly progressive disease) to childhood/adolescence and adulthood (later onset, slower disease progression). Genotype–phenotype analysis in this cohort suggests that higher residual dopamine transporter activity is likely to contribute to postponing disease presentation in these later-onset adult cases. Dopamine transporter deficiency syndrome remains under-recognized and our data highlights that dopamine transporter deficiency syndrome should be considered as a differential diagnosis for both infantile- and juvenile-onset movement disorders, including cerebral palsy and juvenile parkinsonism.
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Title: A homozygous SLITRK6 nonsense mutation is associated with progressive auditory neuropathy in humans Published: March 1, 2014 Publication: Laryngoscope

Authors: Morlet T, Rabinowitz MR, Looney LR, Riegner T, Greenwood LA, Sherman EA, Achilly N, Zhu A, Yoo E, O’Reilly RC, Jinks RN, Puffenberger EG, Heaps A, Morton H, Strauss KA

Abstract:
SLITRK family proteins control neurite outgrowth and regulate synaptic development. In mice, Slitrk6 plays a role in the survival and innervation of sensory neurons in the inner ear, vestibular apparatus, and retina, and also influences axial eye length. We provide the first detailed description of the auditory phenotype in humans with recessive SLITRK6 deficiency.
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Title: Primary Ciliary Dyskinesia-Causing Mutations in Amish and Mennonite Communities Published: August 1, 2013 Publication: The Journal of Pediatrics

Authors: Ferkol TW, Puffenberger EG, Lei H, Helms C, Strauss KA, Bowcock A, Carson JL, Hazucha M, Morton DH, Patel AC, Leigh MW, Knowles MR, Zariwala MA

Abstract:
To determine whether individuals with primary ciliary dyskinesia (PCD) from unrelated Amish and Mennonite families harbor a single and unique founder mutation.
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Title: Rapamycin Prevents Seizures After Depletion of STRADA in a Rare Neurodevelopmental Disorder Published: April 24, 2013 Publication: Science Translational Medicine

Authors: Parker WE, Orlova KA, Parker, WH, Birnbaum JF, Krymskaya VP, Goncharov DA, Baybis M, Helfferich J, Okochi K, Strauss KA, Crino PB

Abstract:
A rare neurodevelopmental disorder in the Old Order Mennonite population called PMSE (polyhydramnios, megalencephaly, and symptomatic epilepsy syndrome; also called Pretzel syndrome) is characterized by infantile-onset epilepsy, neurocognitive delay, craniofacial dysmorphism, and histopathological evidence of heterotopic neurons in subcortical white matter and subependymal regions. PMSE is caused by a homozygous deletion of exons 9 to 13 of the LYK5/STRADA gene, which encodes the pseudokinase STRADA, an upstream inhibitor of mammalian target of rapamycin complex 1 (mTORC1). We show that disrupted pathfinding in migrating mouse neural progenitor cells in vitro caused by STRADA depletion is prevented by mTORC1 inhibition with rapamycin or inhibition of its downstream effector p70 S6 kinase (p70S6K) with the drug PF-4708671 (p70S6Ki). We demonstrate that rapamycin can rescue aberrant cortical lamination and heterotopia associated with STRADA depletion in the mouse cerebral cortex. Constitutive mTORC1 signaling and a migration defect observed in fibroblasts from patients with PMSE were also prevented by mTORC1 inhibition. On the basis of these preclinical findings, we treated five PMSE patients with sirolimus (rapamycin) without complication and observed a reduction in seizure frequency and an improvement in receptive language. Our findings demonstrate a mechanistic link between STRADA loss and mTORC1 hyperactivity in PMSE, and suggest that mTORC1 inhibition may be a potential treatment for PMSE as well as other mTOR-associated neurodevelopmental disorders.
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Title: Biochemical correlates of neuropsychiatric illness in maple syrup urine disease Published: March 8, 2013 Publication: The Journal of Clinical Investigation

Authors: Muelly ER, Moore GJ, Bunce SC, Mack J, Bigler DC, Morton DH, Strauss KA

Abstract:
Maple syrup urine disease (MSUD) is an inherited disorder of branched chain amino acid metabolism presenting with neonatal encephalopathy, episodic metabolic decompensation, and chronic amino acid imbalances. Dietary management enables survival and reduces risk of acute crises. Liver transplantation has emerged as an effective way to eliminate acute decompensation risk. Psychiatric illness is a reported MSUD complication, but has not been well characterized and remains poorly understood. We report the prevalence and characteristics of neuropsychiatric problems among 37 classical MSUD patients (ages 5–35 years, 26 on dietary therapy, 11 after liver transplantation) and explore their underlying mechanisms. Compared with 26 age-matched controls, MSUD patients were at higher risk for disorders of cognition, attention, and mood. Using quantitative proton magnetic resonance spectroscopy, we found lower brain glutamate, N-acetylaspartate (NAA), and creatine concentrations in MSUD patients, which correlated with specific neuropsychiatric outcomes. Asymptomatic neonatal course and stringent longitudinal biochemical control proved fundamental to optimizing long-term mental health. Neuropsychiatric morbidity and neurochemistry were similar among transplanted and nontransplanted MSUD patients. In conclusion, amino acid dysregulation results in aberrant neural networks with neurochemical deficiencies that persist after transplant and correlate with neuropsychiatric morbidities. These findings may provide insight into general mechanisms of psychiatric illness.
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Title: Severity of cardiomyopathy associated with adenine nucleotide translocator-1 deficiency correlates with mtDNA haplogroup Published: February 26, 2013 Publication: Proceedings of the National Academy of Sciences of the United States of America

Authors: Strauss KA, DuBiner L, Simon M, Zargoza M, Sengupta PP, Li P, Narula N, Dreike S, Platt J, Procaccio V, Ortiz-González XR, Puffenberger EG, Kelley RI, Morton DH, Narula J, Wallace DC

Abstract:
Mutations of both nuclear and mitochondrial DNA (mtDNA)–encoded mitochondrial proteins can cause cardiomyopathy associated with mitochondrial dysfunction. Hence, the cardiac phenotype of nuclear DNA mitochondrial mutations might be modulated by mtDNA variation. We studied a 13-generation Mennonite pedigree with autosomal recessive myopathy and cardiomyopathy due to an SLC25A4 frameshift null mutation (c.523delC, p.Q175RfsX38), which codes for the heart-muscle isoform of the adenine nucleotide translocator–1. Ten homozygous null (adenine nucleotide translocator–1−/−) patients monitored over a median of 6 years had a phenotype of progressive myocardial thickening, hyperalaninemia, lactic acidosis, exercise intolerance, and persistent adrenergic activation. Electrocardiography and echocardiography with velocity vector imaging revealed abnormal contractile mechanics, myocardial repolarization abnormalities, and impaired left ventricular relaxation. End-stage heart disease was characterized by massive, symmetric, concentric cardiac hypertrophy; widespread cardiomyocyte degeneration; overabundant and structurally abnormal mitochondria; extensive subendocardial interstitial fibrosis; and marked hypertrophy of arteriolar smooth muscle. Substantial variability in the progression and severity of heart disease segregated with maternal lineage, and sequencing of mtDNA from five maternal lineages revealed two major European haplogroups, U and H. Patients with the haplogroup U mtDNAs had more rapid and severe cardiomyopathy than those with haplogroup H.
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Title: One Community’s Effort to Control Genetic Disease Published: May 17, 2012 Publication: American Journal of Public Health

Authors: Strauss KA, Puffenberger EG, Morton DH

Abstract:
In 1989, we established a small community health clinic to provide care for uninsured Amish and Mennonite children with genetic disorders. Over 20 years, we have used publicly available molecular data and sophisticated technologies to improve diagnostic efficiency, control laboratory costs, reduce hospitalizations, and prevent major neurological impairments within a rural underserved community. These actions allowed the clinic’s 2010 operating budget of $1.5 million to save local communities an estimated $20 to $25 million in aggregate medical costs. This exposes an unsettling fact: our failure to improve the lot of most people stricken with genetic disease is no longer a matter of scientific ignorance or prohibitive costs but of choices we make about how to implement existing knowledge and resources.
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Title: Genetic mapping and exome sequencing identify variants associated with five novel diseases Published: January 17, 2012 Publication: PLOS One

Authors: Puffenberger EG, Jinks RN, Sougnez C, Cibulskis K, Willert RA, Achilly NP, Cassidy RP, Fiorentini CJ, Heiken KF, Lawrence JJ, Mahoney MH, Miller CJ, Nair DT, Politi KA, Worcester KN, Setton RA, Dipiazza R, Sherman EA, Eastman JT, Francklyn C, Robey-Bond S, Rider NL, Gabriel S, Morton DH, Strauss KA

Abstract:
The Clinic for Special Children (CSC) has integrated biochemical and molecular methods into a rural pediatric practice serving Old Order Amish and Mennonite (Plain) children. Among the Plain people, we have used single nucleotide polymorphism (SNP) microarrays to genetically map recessive disorders to large autozygous haplotype blocks (mean = 4.4 Mb) that contain many genes (mean = 79). For some, uninformative mapping or large gene lists preclude disease-gene identification by Sanger sequencing. Seven such conditions were selected for exome sequencing at the Broad Institute; all had been previously mapped at the CSC using low density SNP microarrays coupled with autozygosity and linkage analyses. Using between 1 and 5 patient samples per disorder, we identified sequence variants in the known disease-causing genes SLC6A3 and FLVCR1, and present evidence to strongly support the pathogenicity of variants identified in TUBGCP6, BRAT1, SNIP1, CRADD, and HARS. Our results reveal the power of coupling new genotyping technologies to population-specific genetic knowledge and robust clinical data.
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Title: Liver transplantation for classical maple syrup urine disease: long-term follow-up in 37 patients and comparative United Network for Organ Sharing experience Published: January 1, 2012 Publication: The Journal of Pediatrics

Authors: Mazariegos GV, Morton DH, Sindhi R, Soltys K, Nayyar N, Bond G, Shellmer D, Shneider B, Vockley J, Strauss KA

Abstract:
To assess clinical and neurocognitive function in children who have undergone liver transplantation for classical maple syrup urine disease (MSUD).
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Title: Erythrocyte pyruvate kinase deficiency in an old-order Amish cohort: longitudinal risk and disease management Published: September 1, 2011 Publication: American Journal of Hematology

Authors: Rider NL, Strauss KA, Brown K, Finkenstedt A, Puffenberger EG, Hendrickson CL, Robinson DL, Muenke N, Tselepis C, Saunders L, Zoller H, Morton DH

Abstract:
Pyruvate kinase deficiency is a chronic illness with age specific consequences. Newborns suffer life-threatening hemolytic crisis and hyperbilirubinemia. Adults are at risk for infections because of asplenia, pregnancy-related morbidity, and may suffer organ damage because of systemic iron overload. We describe 27 Old Order Amish patients (ages 8 months-52 years) homozygous for c.1436G>A mutations in PKLR. Each subject had a predictable neonatal course requiring packed red blood cell transfusions (30 ± 5 mL/kg) to control hemolytic disease and intensive phototherapy to prevent kernicterus. Hemochromatosis affected 29% (n = 4) of adult patients, who had inappropriately normal serum hepcidin (34.5 ± 12.7 ng/mL) and GDF-15 (595 ± 335pg/mL) relative to hyperferritinemia (769 ± 595 mg/dL). A high prevalence of HFE gene mutations exists in this population and may contribute to iron-related morbidity. Based on our observations, we present a strategy for long-term management of pyruvate kinase deficiency.
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Title: Safety, efficacy and physiological actions of a lysine-free, arginine-rich formula to treat glutaryl-CoA dehydrogenase deficiency: focus on cerebral amino acid influx. Published: September 1, 2011 Publication: Molecular Genetics and Metabolism

Authors: Strauss KA, Brumbaugh J, Duffy A, Wardley B, Robinson D, Hendrickson C, Tortorelli S, Moser AB, Puffenberger EG, Rider NL, Morton DH

Abstract:
Striatal degeneration from glutaryl-CoA dehydrogenase deficiency (glutaric aciduria type 1, GA1) is associated with cerebral formation and entrapment of glutaryl-CoA and its derivatives that depend on cerebral lysine influx. In 2006 we designed a lysine-free study formula enriched with arginine to selectively block lysine transport across cerebral endothelia and thereby limit glutaryl-CoA production by brain. Between 2006 and present, we treated twelve consecutive children with study formula (LYSx group) while holding all other treatment practices constant. Clinical and biochemical outcomes were compared to 25 GA1 patients (PROx group) treated between 1995 and 2005 with natural protein restriction (dietary lysine/arginine ratio of 1.7±0.3 mg:mg). We used published kinetic parameters of the y+and LAT1 blood-brain barrier transporters to model the influx of amino acids into the brain. Arginine fortification to achieve a mean dietary lysine/arginine ratio of 0.7±0.2 mg:mg was neuroprotective. All 12 LYSx patients are physically and neurologically healthy after 28 aggregate patient-years of follow up (current ages 28±21 months) and there were no adverse events related to formula use. This represents a 36% reduction of neurological risk (95% confidence interval 14-52%, p=0.018) that we can directly attribute to altered amino acid intake. During the first year of life, 20% lower lysine intake and two-fold higher arginine intake by LYSx patients were associated with 50% lower plasma lysine, 3-fold lower plasma lysine/arginine concentration ratio, 42% lower mean calculated cerebral lysine influx, 54% higher calculated cerebral arginine influx, 15-26% higher calculated cerebral influx of several anaplerotic precursors (isoleucine, threonine, methionine, and leucine), 50% less 3-hydroxyglutarate excretion, and a 3-fold lower hospitalization rate (0.8 versus 2.3 hospitalizations per patient per year). The relationship between arginine fortification and plasma lysine indicates that transport competition exists at both cerebrovascular and gastrointestinal barriers, suggesting their co-administration is key to efficacy. Monitoring the ratio between lysine and arginine in diet and plasma may prove a useful strategy for treating children with GA1.
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Title: Reduced thymic output, cell cycle abnormalities, and increased apoptosis of T lymphocytes in patients with cartilage-hair hypoplasia Published: July 1, 2011 Publication: Journal of Allergy and Clinical Immunology

Authors: de la Fuente MA, Recher M, Rider NL, Strauss KA, Morton DH, Adair M, Bonilla FA, Ochs HD, Gelfand EW, Pessach IM, Walter JE, King A, Giliani S, Pai SY, Notarangelo LD

Abstract:
Cartilage-hair hypoplasia (CHH) is characterized by metaphyseal dysplasia, bone marrow failure, increased risk of malignancies, and a variable degree of immunodeficiency. CHH is caused by mutations in the RNA component of the mitochondrial RNA processing (RMRP) endoribonuclease gene, which is involved in ribosomal assembly, telomere function, and cell cycle control.
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Title: A novel mutation of LAMB2 in a multigenerational mennonite family reveals a new phenotypic variant of Pierson syndrome. Ophthalmology Published: June 1, 2011 Publication: Ophthalmology

Authors: Mohney BG, Pulido JS, Lindor NM, Hogan MC, Consugar MB, Peters J, Pankratz VS, Nasr SH, Smith SJ, Gloor J, Kubly V, Spencer D, Nielson R, Puffenberger EG, Strauss KA, Morton DH, Eldahdah L, Harris P

Abstract:
To describe a novel laminin beta-2 (LAMB2) mutation associated with nephritic syndrome and severe retinal disease without microcoria in a large, multi-generational family with Pierson syndrome.
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Title: Contemporary management of congenital malformations of the heart in infants with Ellis – van Creveld syndrome: a report of nine cases Published: April 1, 2011 Publication: Cardiology in the Young

Authors: O’Connor MJ, Rider NL, Thomas Collins R, Hanna BD, Holmes Morton D, Strauss KA

Abstract:
Ellis - van Creveld syndrome is an autosomal recessive disorder manifest by short-limb dwarfism, thoracic dystrophy, postaxial polydactyly, dysplastic nails and teeth, and an approximately 60% incidence of congenital malformations of the heart. Despite patients with Ellis - van Creveld syndrome being regarded as having a high surgical risk, few data are available regarding their outcomes following surgery for congenital malformations of the heart in the current era.
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Title: Homozygous mutation in SAMHD1 gene causes cerebral vasculopathy and early onset stroke Published: March 29, 2011 Publication: Proceedings of the National Academy of Sciences of the United States of America

Authors: Xin B, Jones S, Puffenberger EG, Hinze C, Bright A, Tan H, Zhou A, Wu G, Vargus-Adams J, Agamanolis D, Wang H

Abstract:
We describe an autosomal recessive condition characterized with cerebral vasculopathy and early onset of stroke in 14 individuals in Old Order Amish. The phenotype of the condition was highly heterogeneous, ranging from severe developmental disability to normal schooling. Cerebral vasculopathy was a major hallmark of the condition with a common theme of multifocal stenoses and aneurysms in large arteries, accompanied by chronic ischemic changes, moyamoya morphology, and evidence of prior acute infarction and hemorrhage. Early signs of the disease included mild intrauterine growth restriction, infantile hypotonia, and irritability, followed by failure to thrive and short stature. Acrocyanosis, Raynaud’s phenomenon, chilblain lesions, low-pitch hoarse voice, glaucoma, migraine headache, and arthritis were frequently observed. The early onset or recurrence of strokes secondary to cerebral vasculopathy seems to always be associated with poor outcomes. The elevated erythrocyte sedimentation rate (ESR), IgG, neopterin, and TNF-α found in these patients suggested an immune disorder. Through genomewide homozygosity mapping, we localized the disease gene to chromosome (Chr) 20q11.22-q12. Candidate gene sequencing identified a homozygous mutation, c.1411–2A > G, in the SAMHD1 gene, being associated with this condition. The mutation appeared at the splice-acceptor site of intron 12, resulted in the skipping of exon 13, and gave rise to an aberrant protein with in-frame deletion of 31 amino acids. Immunoblotting analysis showed lack of mutant SAMHD1 protein expression in affected cell lines. The function of SAMHD1 remains unclear, but the inflammatory vasculopathies of the brain found in the patients with SAMHD1 mutation indicate its important roles in immunoregulation and cerebral vascular hemeostasis.
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Title: Investigations of caspr2, an autoantigen of encephalitis and neuromyotonia Published: February 1, 2011 Publication: Annals of Neurology

Authors: Lancaster E, Huijbers MG, Bar V, Boronat A, Wong A, Martinez-Hernandez E, Wilson C, Jacobs D, Lai M, Walker RW, Graus F, Bataller L, Illa I, Markx S, Strauss KA, Peles E, Scherer SS, Dalmau J

Abstract:
To report clinical and immunological investigations of contactin-associated proteinlike 2 (Caspr2), an autoantigen of encephalitis and peripheral nerve hyperexcitability (PNH) previously attributed to voltage-gated potassium channels (VGKC).
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Title: Cognitive and adaptive functioning after liver transplantation for maple syrup urine disease: a case series Published: February 1, 2011 Publication: Pediatric Transplantation

Authors: Shellmer DA, DeVito Dabbs A, Dew MA, Noll RB, Feldman H, Strauss KA, Morton DH, Vockley J, Mazariegos GV

Abstract:
MSUD is a complex metabolic disorder that has been associated with central nervous system damage, developmental delays, and neurocognitive deficits. Although liver transplantation provides a metabolic cure for MSUD, changes in cognitive and adaptive functioning following transplantation have not been investigated. In this report we present data from 14 patients who completed cognitive and adaptive functioning testing pre- and one year and/or three years postliver transplantation. Findings show either no significant change or improvement in IQ scores preto post-liver transplantation. Greater variability was observed in adaptive functioning scores, but the majority of patients evidenced either no significant change or improvement in adaptive scores. In general, findings may indicate that liver transplantation curtails additional central nervous system damage and neurocognitive decline providing an opportunity for stabilization or improvement in functioning.
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Title: Mutations in FLVCR1 cause posterior column ataxia and retinitis pigmentosa Published: November 12, 2010 Publication: The American Journal of Human Genetics

Authors: Rajadhyaksha AM, Elemento O, Puffenberger EG, Schierberl KC, Xiang JZ, Putorti ML, Berciano J, Poulin C, Brais B, Michaelides M, Weleber RG, Higgins JJ

Abstract:
The study of inherited retinal diseases has advanced our knowledge of the cellular and molecular mechanisms involved in sensory neural signaling. Dysfunction of two specific sensory modalities, vision and proprioception, characterizes the phenotype of the rare, autosomal-recessive disorder posterior column ataxia and retinitis pigmentosa (PCARP). Using targeted DNA capture and high-throughput sequencing, we analyzed the entire 4.2 Mb candidate sequence on chromosome 1q32 to find the gene mutated in PCARP in a single family. Employing comprehensive bioinformatic analysis and filtering, we identified a single-nucleotide coding variant in the feline leukemia virus subgroup C cellular receptor 1 (FLVCR1), a gene encoding a heme-transporter protein. Sanger sequencing confirmed the FLVCR1 mutation in this family and identified different homozygous missense mutations located within the protein's transmembrane channel segment in two other unrelated families with PCARP. To determine whether the selective pathologic features of PCARP correlated with FLVCR1 expression, we examined wild-type mouse Flvcr1 mRNA levels in the posterior column of the spinal cord and the retina via quantitative real-time reverse-transcriptase PCR. The Flvcr1 mRNA levels were most abundant in the retina, followed by the posterior column of the spinal cord and other brain regions. These results suggest that aberrant FLVCR1 causes a selective degeneration of a subpopulation of neurons in the retina and the posterior columns of the spinal cord via dysregulation of heme or iron homeostasis. This finding broadens the molecular basis of sensory neural signaling to include common mechanisms that involve proprioception and vision.
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Title: A founder mutation in BBS2 is responsible for Bardet-Biedl syndrome in the Hutterite population: utility of SNP arrays in genetically heterogeneous disorders Published: November 1, 2010 Publication: Clinical Genetics

Authors: Innes AM, Boycott KM, Puffenberger EG, Redl D, MacDonald IM, Chudley AE, Beaulieu C, Perrier R, Gillan T, Wade A, Parboosingh JS

Abstract:
Bardet-Biedl syndrome (BBS) is a multisystem genetically heterogeneous disorder, the clinical features of which are largely the consequence of ciliary dysfunction. BBS is typically inherited in an autosomal recessive fashion, and mutations in at least 14 genes have been identified. Here, we report the identification of a founder mutation in the BBS2 gene as the cause for the increased incidence of this developmental disorder in the Hutterite population. To ascertain the Hutterite BBS locus, we performed a genome-wide single nucleotide polymorphism (SNP) analysis on a single patient and his three unaffected siblings from a Hutterite family. The analysis identified two large SNP blocks that were homozygous in the patient but not in his unaffected siblings, one of these regions contained the BBS2 gene. Sequence analysis and subsequent RNA studies identified and confirmed a novel splice site mutation, c.472-2A>G, in BBS2. This mutation was also found in homozygous form in three subsequently studied Hutterite BBS patients from two different leuts, confirming that this is a founder mutation in the Hutterite population. Further studies are required to determine the frequency of this mutation and its role, if any, in the expression of other ciliopathies in this population.
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Title: A novel autosomal recessive malformation syndrome associated with developmental delay and distinctive facies maps to 16ptel in the Hutterite population Published: June 1, 2010 Publication: American Journal of Medical Genetics Part A

Authors: Boycott KM, Beaulieu C, Puffenberger EG, McLeod DR, Parboosingh JS, Innes AM

Abstract:
The Hutterites are a genetically isolated Anabaptist group living on the North American prairies; their population numbers over 40,000, the majority of whom are descendants of 89 founders. An autosomal recessive developmental disorder was identified in four patients from two consanguineous Hutterite families. To our knowledge the clinical presentation is unique and undescribed. The patients have distinctive facial features, congenital malformations of the heart and genitourinary system, head circumference at the 2nd centile and developmental delay. The facial features include tall forehead with high anterior hairline, deep-set eyes with short, upslanted palpebral fissures, long nose with low-hanging columella, and thick vermilion of the upper and lower lip. Karyotype and baseline metabolic studies were normal. An identity-by-descent mapping approach was used to localize the gene for this disorder. The patients were genotyped using Affymetrix GeneChip Human Mapping 10 K (Xba 2.0) and 50 K (Xba 240) Arrays which identified a single 5.5 Mb homozygous region at chromosome 16p13.3. To confirm and refine the boundaries of this region, microsatellite markers were used to genotype the patients, their parents, and the available unaffected siblings. The disease locus was refined to a region of 5.1 Mb containing 173 known or predicted genes. No other recessive disorders with similar clinical features are currently mapped to this region. The coding regions of over fifteen genes, prioritized by microarray expression analysis and information available in public databases, have been sequenced, but no potential pathogenic mutations have been identified. The identification of the gene for this syndrome will provide new insights into development and learning.
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Title: Classical maple syrup urine disease and brain development: principles of management and formula design Published: April 1, 2010 Publication: Molecular Genetics and Metabolism

Authors: Strauss KA, Wardley B, Robinson D, Hendrickson C, Rider NL, Puffenberger EG, Shellmer D, Moser AB, Morton DH

Abstract:
Branched-chain ketoacid dehydrogenase deficiency results in complex and volatile metabolic derangements that threaten brain development. Treatment for classical maple syrup urine disease (MSUD) should address this underlying physiology while also protecting children from nutrient deficiencies. Based on a 20-year experience managing 79 patients, we designed a study formula to (1) optimize transport of seven amino acids (Tyr, Trp, His, Met, Thr, Gln, Phe) that compete with branched-chain amino acids (BCAAs) for entry into the brain via a common transporter (LAT1), (2) compensate for episodic depletions of glutamine, glutamate, and alanine caused by reverse transamination, and (3) correct deficiencies of omega-3 essential fatty acids, zinc, and selenium widespread among MSUD patients. The formula was enriched with LAT1 amino acid substrates, glutamine, alanine, zinc, selenium, and alpha-linolenic acid (18:3n-3). Fifteen Old Order Mennonite children were started on study formula between birth and 34 months of age and seen at least monthly in the office. Amino acid levels were checked once weekly and more often during illnesses. All children grew and developed normally over a period of 14-33 months. Energy demand, leucine tolerance, and protein accretion were tightly linked during periods of normal growth. Rapid shifts to net protein degradation occurred during illnesses. At baseline, most LAT1 substrates varied inversely with plasma leucine, and their calculated rates of brain uptake were 20-68% below normal. Treatment with study formula increased plasma concentrations of LAT1 substrates and normalized their calculated uptakes into the nervous system. Red cell membrane omega-3 polyunsaturated fatty acids and serum zinc and selenium levels increased on study formula. However, selenium and docosahexaenoic acid (22:6n-3) levels remained below normal. During the study period, hospitalizations decreased from 0.35 to 0.14 per patient per year. There were 28 hospitalizations managed with MSUD hyperalimentation solution; 86% were precipitated by common infections, especially vomiting and gastroenteritis. The large majority of catabolic illnesses were managed successfully at home using 'sick-day' formula and frequent amino acid monitoring. We conclude that the study formula is safe and effective for the treatment of classical MSUD. In principle, dietary enrichment protects the brain against deficiency of amino acids used for protein accretion, neurotransmitter synthesis, and methyl group transfer. Although the pathophysiology of MSUD can be addressed through rational formula design, this does not replace the need for vigilant clinical monitoring, frequent measurement of the complete amino acid profile, and ongoing dietary adjustments that match nutritional intake to the metabolic demands of growth and illness.
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Title: Human ITCH E3 ubiquitin ligase deficiency causes syndromic multisystem autoimmune disease Published: March 12, 2010 Publication: The American Journal of Human Genetics

Authors: Lohr NJ, Molleston JP, Strauss KA, Torres-Martinez W, Sherman EA, Squires RH, Rider NL, Chikwava KR, Cummings OW, Morton DH, Puffenberger EG

Abstract:
Ubiquitin ligases play an important role in the regulation of the immune system. Absence of Itch E3 ubiquitin ligase in mice has been shown to cause severe autoimmune disease. Using autozygosity mapping in a large Amish kindred, we identified a linkage region on chromosome 20 and selected candidate genes for screening. We describe, in ten patients, identification of a mutation resulting in truncation of ITCH. These patients represent the first reported human phenotype associated with ITCH deficiency. These patients not only have multisystem autoimmune disease but also display morphologic and developmental abnormalities. This disorder underscores the importance of ITCH ubiquitin ligase in many cellular processes.
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Title: Homozygous frameshift mutation in TMCO1 causes a syndrome with craniofacial dysmorphism, skeletal anomalies, and mental retardation Published: January 5, 2010 Publication: Proceedings of the National Academy of Sciences of the United States of America

Authors: Xin B, Puffenberger EG, Turben S, Tan H, Zhou A, Wang H

Abstract:
We identified an autosomal recessive condition in 11 individuals in the Old Order Amish of northeastern Ohio. The syndrome was characterized by distinctive craniofacial dysmorphism, skeletal anomalies, and mental retardation. The typical craniofacial dysmorphism included brachycephaly, highly arched bushy eyebrows, synophrys, long eyelashes, low-set ears, microdontism of primary teeth, and generalized gingival hyperplasia, whereas Sprengel deformity of scapula, fusion of spine, rib abnormities, pectus excavatum, and pes planus represented skeletal anomalies. The genome-wide homozygosity mapping using six affected individuals localized the disease gene to a 3.3-Mb region on chromosome 1q23.3-q24.1. Candidate gene sequencing identified a homozygous frameshift mutation, c.139_140delAG, in the transmembrane and coiled-coil domains 1 (TMCO1) gene, as the pathogenic change in all affected members of the extended pedigree. This mutation is predicted to result in a severely truncated protein (p.Ser47Ter) of only one-fourth the original length. The TMCO1 gene product is a member of DUF841 superfamily of several eukaryotic proteins with unknown function. The gene has highly conserved amino acid sequence and is universally expressed in all human tissues examined. The high degree of conservation and the ubiquitous expression pattern in human adult and fetal tissues suggest a critical role for TMCO1. This report shows a TMCO1 sequence variant being associated with a genetic disorder in human. We propose “TMCO1 defect syndrome” as the name of this condition.
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Title: Cerebral haemodynamics in patients with glutaryl-coenzyme A dehydrogenase deficiency Published: January 1, 2010 Publication: Brain

Authors: Strauss KA, Donnelly P, Wintermark M

Abstract:
In glutaric aciduria type 1, glutaryl-coenzyme A and its derivatives are produced from intracerebral lysine and entrapped at high concentrations within the brain, where they interfere with energy metabolism. Biochemical toxicity is thought to trigger stroke-like striatal degeneration in susceptible children under 2 years of age. Here, we explore vascular derangements that might also contribute to brain damage. We studied injured and non-injured Amish glutaric aciduria type 1 patients using magnetic resonance imaging (n = 26), transcranial Doppler ultrasound (n = 35) and perfusion computed tomography (n = 6). All glutaric aciduria type 1 patients had wide middle cerebral, internal carotid and basilar arteries. In non-injured patients, middle cerebral artery velocities were 18-26% below control values throughout late infancy and early childhood, whereas brain-injured children had an early velocity peak (18 months) and low values thereafter. Perfusion scans from six patients showed that tissue blood flow did not undergo a normal developmental surge. We observed four different perfusion patterns. (i) Three children (two non-injured) had low cerebral blood flow, prolonged mean transit time, elevated cerebral blood volume and high mean transit time/cerebral blood flow and cerebral blood volume/cerebral blood flow ratios. This pattern optimizes substrate extraction at any given flow rate but indicates low perfusion pressure and limited autoregulatory reserve. (ii) Ten hours after the onset of striatal necrosis in an 8-month-old infant, mean transit time and cerebral blood volume were low relative to cerebral blood flow, which varied markedly from region to region. This pattern indicates disturbed autoregulation, regional perfusion pressure gradients, or redistribution of flow from functional capillaries to non-exchanging vessels. (iii) In an infant with atrophic putaminal lesions, striatal flow was normal but mean transit time and cerebral blood volume were low, consistent with perfusion in excess of metabolic demand. (iv) Finally, a brain-injured adult with glutaric aciduria type 1 had regional perfusion values within the normal range, but the putamina, which normally have the highest regional perfusion, had cerebral blood flow values 24% below cortical grey matter. Although metabolic toxicity appears central to the pathophysiology of striatal necrosis, cerebrovascular changes probably also contribute to the process. These changes may be the primary cause of expanded cerebrospinal fluid volume in newborns, intracranial and retinal haemorrhages in infants and interstitial white matter oedema in children and adults. This pilot study suggests important new areas for clinical investigation.
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Title: Genetics, medicine, and the Plain people Published: July 16, 2009 Publication: Annual Review of Genomics and Human Genetics

Authors: Strauss KA, Puffenberger EG

Abstract:
The Old Order Amish and Old Order Mennonite populations of Pennsylvania are descended from Swiss Anabaptist immigrants who came to the New World in the early eighteenth century. Today they live in many small endogamous demes across North America. Genetically, these demes have dissimilar allele frequencies and disease spectra owing to unique founders. Biological and social aspects of Old Order communities make them ideal for studies in population genetics and genomic medicine, and over the last 40 years, advances in genomic science coincided with investigational studies in Plain populations. Newer molecular genetic technologies are sufficiently informative, rapid, and flexible to use in a clinical setting, and we have successfully integrated these tools into a rural pediatric practice. Our studies with the Pennsylvania Plain communities show that population-specific genetic knowledge provides a powerful framework in which to prevent disease, reduce medical costs, and create new insights into human biology.
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Title: Gene structure and mutations of glutaryl-coenzyme A dehydrogenase: impaired association of enzyme subunits that is due to an A421V substitution causes glutaric acidemia type I in the Amish Published: July 16, 2009 Publication: Annual Review of Genomics and Human Genetics

Authors: Biery BJ, Stein DE, Morton DH, Goodman SI

Abstract:
The structure of the human glutaryl coenzyme A dehydrogenase (GCD) gene was determined to contain 11 exons and to span approximately 7 kb. Fibroblast DNA from 64 unrelated glutaric acidemia type I (GA1) patients was screened for mutations by PCR amplification and analysis of SSCP. Fragments with altered electrophoretic mobility were subcloned and sequenced to detect mutations that caused GA1. This report describes the structure of the GCD gene, as well as point mutations and polymorphisms found in 7 of its 11 exons. Several mutations were found in more than one patient, but no one prevalent mutation was detected in the general population. As expected from pedigree analysis, a single mutant allele causes GA1 in the Old Order Amish of Lancaster County, Pennsylvania. Several mutations have been expressed in Escherichia coli, and all produce diminished enzyme activity. Reduced activity in GCD encoded by the A421V mutation in the Amish may be due to impaired association of enzyme subunits.
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Title: Immunologic and clinical features of 25 Amish patients with RMRP 70 A–>G cartilage hair hypoplasia Published: April 1, 2009 Publication: Clinical Immunology

Authors: Rider NL, Morton DH, Puffenberger E, Hendrickson CL, Robinson DL, Strauss KA

Abstract:
Cartilage-hair hypoplasia is a short limbed skeletal dysplasia associated with impairments in host-defense. To better understand the clinical heterogeneity of this disorder, we studied 25 Amish patients with homozygous mutations in RMRP (RMRP 70 A>G). Despite mutation homogeneity, eight (32%) patients had severe or recurrent infections, two (8%) of these children underwent bone-marrow transplantation for combined immunodeficiency, and the remainder were healthy. Features distinguishing patients who underwent bone marrow transplantation from others were shorter birth length, and lower serum IgG, undetectable serum IgA, and elevated circulating NK cells before 2 years of age. Irrespective of clinical phenotype, most patients had lymphopenia and reduced lymphocyte proliferation to mitogens in vitro. Our cohort analysis suggests that many patients with cartilage-hair hypoplasia are at risk for infection susceptibility particularly during the first 2 years of life. Gauging this risk is difficult, and thus careful monitoring of all patients with cartilage-hair hypoplasia is warranted.
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Title: A multiplex human syndrome implicates a key role for intestinal cell kinase in development of central nervous, skeletal, and endocrine systems Published: February 13, 2009 Publication: The American Journal of Human Genetics

Authors: Lahiry P, Wang J, Robinson JF, Turowec JP, Litchfield DW, Lanktree MB, Gloor GB, Puffenberger EG, Strauss KA, Martens MB, Ramsay DA, Rupar CA, Siu V, Hegele RA

Abstract:
Six infants in an Old Order Amish pedigree were observed to be affected with endocrine-cerebro-osteodysplasia (ECO). ECO is a previously unidentified neonatal lethal recessive disorder with multiple anomalies involving the endocrine, cerebral, and skeletal systems. Autozygosity mapping and sequencing identified a previously unknown missense mutation, R272Q, in ICK, encoding intestinal cell kinase (ICK). Our results established that R272 is conserved across species and among ethnicities, and three-dimensional analysis of the protein structure suggests protein instability due to the R272Q mutation. We also demonstrate that the R272Q mutant fails to localize at the nucleus and has diminished kinase activity. These findings suggest that ICK plays a key role in the development of multiple organ systems.
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Title: Mutations in cystathionine beta-synthase or methylenetetrahydrofolate reductase gene increase N-homocysteinylated protein levels in humans Published: December 1, 2008 Publication: The FASEB Journal

Authors: Jakubowski H, Boers GH, Strauss KA

Abstract:
Severely elevated plasma homocysteine(Hcy) levels observed in genetic disorders of Hcymetabolism are associated with pathologies in multipleorgans and lead to premature death due to vascularcomplications. In addition to elevating plasma Hcy,mutations in cystathionine ␤-synthase (CBS) or methyl-enetetrahydrofolate reductase (MTHFR) gene lead tomarkedly elevated levels of circulating Hcy-thiolactone.The thiooester chemistry of Hcy-thiolactone underliesits ability to form isopeptide bonds with protein lysineresidues (N-Hcy-protein), which may impair or alter theprotein’s function. However, it was not known whethergenetic deficiencies in Hcy metabolism affect N-Hcy-protein levels in humans. Here we show that plasmaN-Hcy-protein levels are significantly elevated in CBS-and MTHFR-deficient patients. We also show that CBS-deficient patients have significantly elevated plasma levelsof prothrombotic N-Hcy-fibrinogen. These results pro-vide a possible explanation for increased atherothrombo-sis observed in CBS-deficient patients.
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Title: Genetic mapping of glutaric aciduria, type 3, to chromosome 7 and identification of mutations in c7orf10 Published: November 17, 2008 Publication: The American Journal of Human Genetics

Authors: Sherman EA, Strauss KA, Tortorelli S, Bennett MJ, Knerr I, Morton DH, Puffenberger EG

Abstract:
While screening Old Order Amish children for glutaric aciduria type 1 (GA1) between 1989 and 1993, we found three healthy children who excreted abnormal quantities of glutaric acid but low 3-hydroxyglutaric acid, a pattern consistent with glutaric aciduria type 3 (GA3). None of these children had the GCDH c.1262C→T mutation that causes GA1 among the Amish. Using single-nucleotide polymorphism (SNP) genotypes, we identified a shared homozygous 4.7 Mb region on chromosome 7. This region contained 25 genes including C7orf10, an open reading frame with a putative mitochondrial targeting sequence and coenzyme-A transferase domain. Direct sequencing of C7orf10 revealed that the three Amish individuals were homozygous for a nonsynonymous sequence variant (c.895C→T, Arg299Trp). We then sequenced three non-Amish children with GA3 and discovered two nonsense mutations (c.322C→T, Arg108Ter, and c.424C→T, Arg142Ter) in addition to the Amish mutation. Two pathogenic alleles were identified in each of the six patients. There was no consistent clinical phenotype associated with GA3. In affected individuals, urine molar ratios of glutarate to its derivatives (3-hydroxyglutarate, glutarylcarnitine, and glutarylglycine) were elevated, suggesting impaired formation of glutaryl-CoA. These observations refine our understanding of the lysine-tryptophan degradation pathway and have important implications for the pathophysiology of GA1.
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