We used single nucleotide polymorphism (SNP) microarrays to investigate the cause of a symptomatic epilepsy syndrome in a group of seven distantly related Old Order Mennonite children. Autozygosity mapping was inconclusive, but closer inspection of the data followed by formal SNP copy number analyses showed that all affected patients had homozygous deletions of a single SNP (rs721575) and their parents were hemizygous for this marker. The deleted SNP marked a larger deletion encompassing exons 9-13 of LYK5, which encodes STE20-related adaptor protein, a pseudokinase necessary for proper localization and function of serine/threonine kinase 11 (a.k.a. LKB1). Homozygous LYK5 deletions were associated with polyhydramnios, preterm labour and distinctive craniofacial features. Affected children had large heads, infantile-onset intractable multifocal seizures and severe psychomotor retardation. We designated this condition PMSE syndrome (polyhydramnios, megalencephaly and symptomatic epilepsy). Thirty-eight percent (N = 16) of affected children died during childhood (ages 7 months to 6 years) from medical complications of the disorder, which included status epilepticus, congestive heart failure due to atrial septal defect and hypernatremic dehydration due to diabetes insipidus. A single post-mortem neuropathological study revealed megalencephaly, ventriculomegaly, cytomegaly and extensive vacuolization and astrocytosis of white matter. There was abundant anti-phospho-ribosomal S6 labelling of large cells within the frontal cortex, basal ganglia, hippocampus and spinal cord, consistent with constitutive activation of the mammalian target of rapamycin (mTOR) signalling pathway in brain.

Genetic disorders of homocysteine(Hcy) metabolism or a high-methionine diet lead toelevations of plasma Hcy levels. In humans, severegenetic hyperhomocysteinemia results in prematuredeath from vascular complications whereas dietaryhyperhomocysteinemia is often used to induce athero-sclerosis in animal models. Hcy is mistakenly selectedin place of methionine by methionyl-tRNA synthetaseduring protein biosynthesis, which results in the forma-tion of Hcy-thiolactone and initiates a pathophysiolog-ical pathway that has been implicated in human vasculardisease. However, whether genetic deficiencies in Hcymetabolism or a high-methionine diet affect Hcy-thio-lactone levels in mammals has been unknown. Here weshow that plasma Hcy-thiolactone is elevated 59-foldand 72-fold in human patients with hyperhomocysteine-mia secondary to mutations in methylenetetrahydrofo-late reductase and cystathionine -synthase genes, re-spectively. We also show that mice, like humans,eliminate Hcy-thiolactone by urinary excretion; in con-trast to humans, however, mice also eliminate signifi-cant amounts of plasma total Hcy (38%) by urinaryexcretion. In mice, hyperhomocysteinemia secondaryto a high-methionine diet leads to 3.7-fold and 25-foldincreases in plasma and urinary Hcy-thiolactone levels,respectively. Thus, we conclude that hyperhomocys-teinemia leads to significant increases in the athero-genic metabolite Hcy-thiolactone in humans and mice.

Over a four-year period, we collected clinical and biochemical data from five Amish children who were homozygous for missense mutations in 5,10-methylenetetrahydrofolate reductase (MTHFR c.1129C>T). The four oldest patients had irreversible brain damage prior to diagnosis. The youngest child, diagnosed and started on betaine therapy as a newborn, is healthy at her present age of three years. We compared biochemical data among four groups: 16 control subjects, eight heterozygous parents, and five affected children (for the latter group, both before and during treatment with betaine anhydrous). Plasma amino acid concentrations were used to estimate changes in cerebral methionine uptake resulting from betaine therapy. In all affected children, treatment with betaine (534+/-222 mg/kg/day) increased plasma S-adenosylmethionine, improved markers of tissue methyltransferase activity, and resulted in a threefold increase of calculated brain methionine uptake. Betaine therapy did not normalize plasma total homocysteine, nor did it correct cerebral 5-methyltetrahydrofolate deficiency. We conclude that when the 5-methyltetrahydrofolate content of brain tissue is low, dietary betaine sufficient to increase brain methionine uptake may compensate for impaired cerebral methionine recycling. To effectively support the metabolic requirements of rapid brain growth, a large dose of betaine should be started early in life.

Novel comparison of CDT isoforms as determined by CE with an FDA-approved immunoassay kit.

We summarize the treatment of 20 patients with Crigler-Najjar disease (CND) managed at one center from 1989 to 2005 (200 patient-years). Diagnosis was confirmed by sequencing the UGTA1A gene. Nineteen patients had a severe (type 1) phenotype. Major treatment goals were to maintain the bilirubin to albumin concentration ratio at <0.5 in neonates and <0.7 in older children and adults, to avoid drugs known to displace bilirubin from albumin, and to manage temporary exacerbations of hyperbilirubinemia caused by illness or gallstones. A variety of phototherapy systems provided high irradiance over a large body surface. Mean total bilirubin for the group was 16+/-5 mg/dl and increased with age by approximately 0.8 mg/dl per year. The molar ratio of bilirubin to albumin ranged from 0.17 to 0.75 (mean: 0.44). The overall non-surgical hospitalization rate was 0.12 hospitalizations per patient per year; one-half of these were for neonatal hyperbilirubinemia and the remainder were for infectious illnesses. Ten patients (50%) underwent elective laproscopic cholecystectomy for cholelithiasis. No patient required invasive bilirubin removal or developed bilirubin-induced neurological damage under our care. Visual acuity and color discrimination did not differ between CND patients and age-matched sibling controls. Four patients treated with orthotopic liver transplantation were effectively cured of CND, although one suffered significant transplant-related complications.Conclusions. While patients await liver transplantation for CND, hyperbilirubinemia can be managed safely and effectively to prevent kernicterus. Lessons learned from CND can be applied to screening and therapy of non-hemolytic jaundice in otherwise healthy newborns.

Contactin-associated protein-like 2 (CASPR2) is encoded by CNTNAP2 and clusters voltage-gated potassium channels (K v 1.1) at the nodes of Ranvier. We report a homozygous mutation of CNTNAP2 in Old Order Amish children with cortical dysplasia, focal epilepsy, relative macrocephaly, and diminished deep-tendon reflexes. Intractable focal seizures began in early childhood, after which language regression, hyperactivity, impulsive and aggressive behavior, and mental retardation developed in all children. Resective surgery did not prevent the recurrence of seizures. Temporal-lobe specimens showed evidence of abnormalities of neuronal migration and structure, widespread astrogliosis, and reduced expression of CASPR2.

An 8.5-year-old girl with classical maple syrup urine disease (MSUD) required liver transplantation for hypervitaminosis A and was effectively cured of MSUD over an 8-year clinical follow-up period. We developed a collaborative multidisciplinary effort to evaluate the effects of elective liver transplantation in 10 additional children (age range 1.9–20.5 years) with classical MSUD. Patients were transplanted with whole cadaveric livers under a protocol designed to optimize safe pre- and post-transplant management of MSUD. All patients are alive and well with normal allograft function after 106 months of follow-up in the index patient and a median follow-up period of 14 months (range 4–18 months) in the 10 remaining patients. Leucine, isoleucine and valine levels stabilized within 6 hours post-transplant and remained so on an unrestricted protein intake in all patients. Metabolic cure was documented as a sustained increase in weight-adjusted leucine tolerance, normalization of plasma concentration relationships among branched-chain and other essential and nonessential amino acids, and metabolic and clinical stability during protein loading and intercurrent illnesses. Costs and risks associated with surgery and immune suppression were similar to other pediatric liver transplant populations.