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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The primary goal of our research will always be to find effective and affordable treatments for patients. Over the years, we have shared our methods and discoveries with the broader scientific community.
In the over 30 years since the Clinic's founding, our staff have published more than 120 peer-reviewed research papers, fueled by close collaboration between our clinical and laboratory teams and effective relationships with academic, scientific, and clinical partners.
Authors: Erin L. Crowgey, Michael C. Washburn, E. Anders Kolb, Erik G. Puffenberger
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.
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
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.
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
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.
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
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.
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
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.
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
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.
Authors: Carson VJ, Puffenberger EG, Bowser LE, Brigatti KW, Young M, Korulczyk D, Rodrigues AS, Loeven KK, Strauss KA
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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Our clinic serves as a trusted medical home for families working to prevent and treat genetic illness in their children. Serving predominantly Amish and Mennonite families, the sturdy, timber-framed building was "raised" by the hands of those in the Anabaptist community outside of Strasburg, PA. Inside the clinic is filled with an array of high-tech gene sequencing that allows us to deliver state of the art care in a nurturing environment.