Publications by authors named "Jirair K Bedoyan"

31 Publications

Novel presentations associated with a PDHA1 variant - Alternating hemiplegia in Hemizygote proband and Guillain Barre Syndrome in Heterozygote mother.

Eur J Paediatr Neurol 2021 Mar 22;31:27-30. Epub 2021 Jan 22.

Division of Neurogenetics and Developmental Pediatrics, Children's National Hospital, Washington DC, USA.

We report a 5-year-old male with a PDHA1 variant who presented with alternating hemiplegia of childhood and later developed developmental regression, basal ganglia injury and episodic lactic acidosis. Enzyme assay in lymphocytes confirmed a diagnosis of Pyruvate Dehydrogenase Complex (PDC) deficiency. His mother who was heterozygous for the same variant suffered from ophthalmoplegia, chronic migraine and developed flaccid paralysis at 36 years of age. PDHA1 is the most common genetic cause of PDC deficiency and presents with a myriad of neurological phenotypes including neonatal form with lactic acidosis, non-progressive infantile encephalopathy, Leigh syndrome subtype and intermittent ataxia. The presentations in our 2 patients contribute to the clinical heterogeneity of this neurogenetic condition.
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http://dx.doi.org/10.1016/j.ejpn.2021.01.006DOI Listing
March 2021

Enantiomer-specific pharmacokinetics of D,L-3-hydroxybutyrate: Implications for the treatment of multiple acyl-CoA dehydrogenase deficiency.

J Inherit Metab Dis 2021 Feb 5. Epub 2021 Feb 5.

University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Section of Metabolic Diseases, Groningen, The Netherlands.

D,L-3-hydroxybutyrate (D,L-3-HB, a ketone body) treatment has been described in several inborn errors of metabolism, including multiple acyl-CoA dehydrogenase deficiency (MADD; glutaric aciduria type II). We aimed to improve the understanding of enantiomer-specific pharmacokinetics of D,L-3-HB. Using UPLC-MS/MS, we analyzed D-3-HB and L-3-HB concentrations in blood samples from three MADD patients, and blood and tissue samples from healthy rats, upon D,L-3-HB salt administration (patients: 736-1123 mg/kg/day; rats: 1579-6317 mg/kg/day of salt-free D,L-3-HB). D,L-3-HB administration caused substantially higher L-3-HB concentrations than D-3-HB. In MADD patients, both enantiomers peaked at 30 to 60 minutes, and approached baseline after 3 hours. In rats, D,L-3-HB administration significantly increased C and AUC of D-3-HB in a dose-dependent manner (controls vs ascending dose groups for C : 0.10 vs 0.30-0.35-0.50 mmol/L, and AUC: 14 vs 58-71-106 minutes*mmol/L), whereas for L-3-HB the increases were significant compared to controls, but not dose proportional (C : 0.01 vs 1.88-1.92-1.98 mmol/L, and AUC: 1 vs 380-454-479 minutes*mmol/L). L-3-HB concentrations increased extensively in brain, heart, liver, and muscle, whereas the most profound rise in D-3-HB was observed in heart and liver. Our study provides important knowledge on the absorption and distribution upon oral D,L-3-HB. The enantiomer-specific pharmacokinetics implies differential metabolic fates of D-3-HB and L-3-HB.
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http://dx.doi.org/10.1002/jimd.12365DOI Listing
February 2021

A Novel Homozygous Missense Mutation in the Gene: Expanding the Phenotype of Multisystem Disease.

J Endocr Soc 2021 Feb 2;5(2):bvaa196. Epub 2021 Jan 2.

Division of Pediatric Endocrinology, Department of Pediatrics, University Hospitals Cleveland Medical Center/Rainbow Babies and Children's Hospital, Case Western University School of Medicine, Cleveland, OH, USA.

Aminoacyl-tRNA synthetases (ARSs) are crucial enzymes for protein translation. Mutations in genes encoding ARSs are associated with human disease. Tyrosyl-tRNA synthetase is encoded by which is ubiquitously expressed and implicated in an autosomal dominant form of Charcot-Marie-Tooth and autosomal recessive related multisystem disease. We report on a former 34-week gestational age male who presented at 2 months of age with failure to thrive (FTT) and cholestatic hepatitis. He was subsequently diagnosed with hyperinsulinemic hypoglycemia with a negative congenital hyperinsulinism gene panel and F-DOPA positron-emission tomography (PET) scan that did not demonstrate a focal lesion. Autopsy findings were notable for overall normal pancreatic islet size and morphology. Trio whole exome sequencing identified a novel homozygous variant of uncertain significance in (c.611A > C, p.Tyr204Cys) with each parent a carrier for the variant. Euglycemia was maintained with diazoxide (max dose, 18 mg/kg/day), and enteral dextrose via gastrostomy tube (G-Tube). During his prolonged hospitalization, the patient developed progressive liver disease, exocrine pancreatic insufficiency, acute renal failure, recurrent infections, ichthyosis, hematologic concerns, hypotonia, and global developmental delay. Such multisystem features have been previously reported in association with pathogenic mutations. Although hypoglycemia has been associated with pathogenic mutations, this report provides more conclusive data that a variant can cause hyperinsulinemic hypoglycemia. This case expands the allelic and clinical heterogeneity of -related disease. In addition, -related disease should be considered in the differential of hyperinsulinemic hypoglycemia associated with multisystem disease.
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http://dx.doi.org/10.1210/jendso/bvaa196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806200PMC
February 2021

Utility of specific amino acid ratios in screening for pyruvate dehydrogenase complex deficiencies and other mitochondrial disorders associated with congenital lactic acidosis and newborn screening prospects.

JIMD Rep 2020 Nov 16;56(1):70-81. Epub 2020 Aug 16.

Pediatrics CWRU Cleveland Ohio USA.

Pyruvate dehydrogenase complex deficiencies (PDCDs) and other mitochondrial disorders (MtDs) can (a) result in congenital lactic acidosis with elevations of blood alanine (Ala) and proline (Pro), (b) lead to decreased ATP production, and (c) result in high morbidity and mortality. With ~140,000 live births annually in Ohio and ~1 in 9,000 overall prevalence of MtDs, we estimate 2 to 3 newborns will have PDCD and 13 to 14 others likely will have another MtD annually. We compared the sensitivities of plasma amino acids (AA) Alanine (Ala), Alanine:Leucine (Ala:Leu), Alanine:Lysine and the combination of Ala:Leu and Proline:Leucine (Pro:Leu), in subjects with known primary-specific PDCD due to and mutations vs controls. Furthermore, in collaboration with the Ohio newborn screening (NBS) laboratory, we determined Ala and Pro concentrations in dried blood spot (DBS) specimens using existing NBS analytic approaches and evaluated Ala:Leu and Pro:Leu ratios from DBS specimens of 123,414 Ohio newborns in a 12-month period. We used the combined Ala:Leu ≥4.0 and Pro:Leu ≥3.0 ratio criterion from both DBS and plasma specimens as a screening tool in our retrospective review of newborn data. The screening tool applied on DBS and/or plasma (or serum) AA specimens successfully identified three unrelated females with novel mutations, one male with a novel X-linked mutation, and a female with mutations. This work lays the first step for piloting an NBS protocol in Ohio for identifying newborns at high risk for primary-specific PDCD and other MtDs who might benefit from neonatal diagnosis and early institution of known therapy and/or potential novel therapies for such disorders.
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http://dx.doi.org/10.1002/jmd2.12153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653239PMC
November 2020

The E273del variant of uncertain significance of the ornithine transcarbamylase gene - a case for reclassification.

Mol Genet Metab Rep 2020 Jun 8;23:100598. Epub 2020 May 8.

Department of Genetics and Genome Sciences, CWRU, Cleveland, OH, USA.

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http://dx.doi.org/10.1016/j.ymgmr.2020.100598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218070PMC
June 2020

Mitochondrial diseases in North America: An analysis of the NAMDC Registry.

Neurol Genet 2020 Apr 2;6(2):e402. Epub 2020 Mar 2.

Department of Neurology (E.B., V.E., S.D., K.E., X.Q.R., M.H.), Columbia University Medical Center, New York; Department of Biostatistics (Y.L., V.C., J.K., J. Grier, R.B., J.L.P.T.), Mailman School of Public Health, Columbia University, New York; Radboudumc (R.S.), Nijmegen, The Netherlands; Department of Pediatrics (B.H.C.), Northeast Ohio Medical University and Akron Children's Hospital; Genetics Unit (A.K.), Massachusetts General Hospital, Boston; Department of Pediatrics (G.D.V.), State University of New York at Buffalo; Departments of Neurosciences and Pediatrics (R.H.), University of California at San Diego; Department of Pediatrics (J.L.K.V.H., A.L.), University of Colorado School of Medicine, Aurora; Department of Molecular and Human Genetics (F.S.), Baylor College of Medicine, Houston, TX; Texas Children's Hospital (F.S.), Houston; Joint BCM-CUHK Center of Medical Genetics (F.S.), Prince of Wales Hospital, ShaTin, New Territories, Hong Kong; Department of Neurology (S.P.), Cleveland Clinic, OH; Departments of Genetics and Genome Sciences and Pediatrics (J.K.B., S.D.D.), and Center for Human Genetics, University Hospitals Cleveland Medical Center, Case Western Reserve University, OH; Departments of Neurology and Clinical Genomics (R.H.G.), Mayo Clinic, Rochester, MN; Department of Neurology (R.P.S.), University of Washington, Seattle Children's Hospital; Department of Pediatrics (G.M.E.), Stanford University, Palo Alto, CA; Department of Medicine (P.W.S.), University of Florida at Gainesville; Genetics and Genomic Sciences at the Icahn School of Medicine at Mount Sinai (J. Ganesh), New York; Mitochondrial Medicine Frontier Program (Z.Z.-C., M.J.F., A.C.G.), Division of Human Genetics, The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine; University of Pennsylvania Perelman School of Medicine (Z.Z.-C.), Philadelphia; Department of Neurology (M.T.), McMasters University, Toronto, Ontario, Canada; Department of Neurology (A.G.), Children's National Health Network, Washington, DC; Office of Dietary Supplements (K.C.), National Institutes of Health, Bethesda, MD; and Eunice Kennedy Shriver National Institute of Child Health and Human Development (D.K.), National Institutes of Health, Bethesda, MD.

Objective: To describe clinical, biochemical, and genetic features of participants with mitochondrial diseases (MtDs) enrolled in the North American Mitochondrial Disease Consortium (NAMDC) Registry.

Methods: This cross-sectional, multicenter, retrospective database analysis evaluates the phenotypic and molecular characteristics of participants enrolled in the NAMDC Registry from September 2011 to December 2018. The NAMDC is a network of 17 centers with expertise in MtDs and includes both adult and pediatric specialists.

Results: One thousand four hundred ten of 1,553 participants had sufficient clinical data for analysis. For this study, we included only participants with molecular genetic diagnoses (n = 666). Age at onset ranged from infancy to adulthood. The most common diagnosis was multisystemic disorder (113 participants), and only a minority of participants were diagnosed with a classical mitochondrial syndrome. The most frequent classical syndromes were Leigh syndrome (97 individuals) and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (71 individuals). Pathogenic variants in the mitochondrial DNA were more frequently observed (414 participants) than pathogenic nuclear gene variants (252 participants). Pathogenic variants in 65 nuclear genes were identified, with and being the most commonly affected. Pathogenic variants in 38 genes were reported only in single participants.

Conclusions: The NAMDC Registry data confirm the high variability of clinical, biochemical, and genetic features of participants with MtDs. This study serves as an important resource for future enhancement of MtD research and clinical care by providing the first comprehensive description of participant with MtD in North America.
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http://dx.doi.org/10.1212/NXG.0000000000000402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164977PMC
April 2020

Consensus guidelines for management of hyperammonaemia in paediatric patients receiving continuous kidney replacement therapy.

Nat Rev Nephrol 2020 08 8;16(8):471-482. Epub 2020 Apr 8.

Division of Nephrology, University of Missouri-Kansas City School of Medicine, Children's Mercy, Kansas City, MO, USA.

Hyperammonaemia in children can lead to grave consequences in the form of cerebral oedema, severe neurological impairment and even death. In infants and children, common causes of hyperammonaemia include urea cycle disorders or organic acidaemias. Few studies have assessed the role of extracorporeal therapies in the management of hyperammonaemia in neonates and children. Moreover, consensus guidelines are lacking for the use of non-kidney replacement therapy (NKRT) and kidney replacement therapies (KRTs, including peritoneal dialysis, continuous KRT, haemodialysis and hybrid therapy) to manage hyperammonaemia in neonates and children. Prompt treatment with KRT and/or NKRT, the choice of which depends on the ammonia concentrations and presenting symptoms of the patient, is crucial. This expert Consensus Statement presents recommendations for the management of hyperammonaemia requiring KRT in paediatric populations. Additional studies are required to strengthen these recommendations.
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http://dx.doi.org/10.1038/s41581-020-0267-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7366888PMC
August 2020

Life-threatening presentations of propionic acidemia due to the Amish founder variant.

Mol Genet Metab Rep 2019 Dec 6;21:100537. Epub 2019 Nov 6.

Center for Human Genetics, University Hospitals Cleveland Medical Center, Cleveland, OH, United States of America.

Although individuals of Amish descent with propionic acidemia (PA) are generally thought to have a milder disease phenotype, we now have a better understanding of the natural history of PA in this population. Here we describe two Amish patients with emergent presentations of PA, one with metabolic decompensation and another with cardiogenic shock. PA can present with life-threatening metabolic decompensation or an adult-onset severe cardiomyopathy. We discuss critical clinical implications of this observation.
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http://dx.doi.org/10.1016/j.ymgmr.2019.100537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6895572PMC
December 2019

A novel null mutation in the pyruvate dehydrogenase phosphatase catalytic subunit gene () causing pyruvate dehydrogenase complex deficiency.

JIMD Rep 2019 Jul 17;48(1):26-35. Epub 2019 Jun 17.

Division of Genetics and Genomics, The Manton Center for Orphan Disease Research Boston Children's Hospital, Harvard Medical School Boston Massachusetts.

Congenital lactic acidosis due to pyruvate dehydrogenase phosphatase (PDP) deficiency is very rare. PDP regulates pyruvate dehydrogenase complex (PDC) and defective PDP leads to PDC deficiency. We report a case with functional PDC deficiency with low activated (+dichloroacetate) and inactivated (+fluoride) PDC activities in lymphocytes and fibroblasts, normal activity of other mitochondrial enzymes in fibroblasts, and novel biallelic frameshift mutation in the gene, c.575dupT (p.L192FfsX5), with absent PDP1 product in fibroblasts. Unexpectedly, the patient also had low branched-chain 2-ketoacid dehydrogenase (BCKDH) activity in fibroblasts with slight elevation of branched-chain amino acids in plasma and ketoacids in urine but with no pathogenic mutations in the enzymes of BCKDH, which could suggest shared regulatory function of PDC and BCKDH in fibroblasts, potentially in other tissues or cell types as well, but this remains to be determined. The clinical presentation of this patient overlaps that of other patients with primary-specific PDC deficiency, with neonatal/infantile and childhood lactic acidosis, normal lactate to pyruvate ratio, elevated plasma alanine, delayed psychomotor development, epileptic encephalopathy, feeding difficulties, and hypotonia. This patient exhibited marked improvement of overall development following initiation of ketogenic diet at 31 months of age. To the best of our knowledge, this is the fourth case of functional PDC deficiency with a defined mutation in .

Synopsis: Pyruvate dehydrogenase phosphatase (PDP) regulates pyruvate dehydrogenase complex (PDC) and defective PDP due to mutations leads to PDC deficiency and congenital lactic acidosis.
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http://dx.doi.org/10.1002/jmd2.12054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6606986PMC
July 2019

Impact of Diagnosis and Therapy on Cognitive Function in Urea Cycle Disorders.

Ann Neurol 2019 07 13;86(1):116-128. Epub 2019 May 13.

Center for Pediatric and Adolescent Medicine, Division of Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany.

Objective: Individuals with urea cycle disorders (UCDs) often present with intellectual and developmental disabilities. The major aim of this study was to evaluate the impact of diagnostic and therapeutic interventions on cognitive outcomes in UCDs.

Methods: This prospective, observational, multicenter study includes data from 503 individuals with UCDs who had comprehensive neurocognitive testing with a cumulative follow-up of 702 patient-years.

Results: The mean cognitive standard deviation score (cSDS) was lower in symptomatic than in asymptomatic (p < 0.001, t test) individuals with UCDs. Intellectual disability (intellectual quotient < 70, cSDS < -2.0) was associated with the respective subtype of UCD and early disease onset, whereas height of the initial peak plasma ammonium concentration was inversely associated with neurocognitive outcomes in mitochondrial (proximal) rather than cytosolic (distal) UCDs. In ornithine transcarbamylase and argininosuccinate synthetase 1 deficiencies, we did not find evidence that monoscavenger therapy with sodium or glycerol phenylbutyrate was superior to sodium benzoate in providing cognitive protection. Early liver transplantation appears to be beneficial for UCDs. It is noteworthy that individuals with argininosuccinate synthetase 1 and argininosuccinate lyase deficiencies identified by newborn screening had better neurocognitive outcomes than those diagnosed after the manifestation of first symptoms.

Interpretation: Cognitive function is related to interventional and non-interventional variables. Early detection by newborn screening and early liver transplantation appear to offer greater cognitive protection, but none of the currently used nitrogen scavengers was superior with regard to long-term neurocognitive outcome. Further confirmation could determine these variables as important clinical indicators of neuroprotection for individuals with UCDs. ANN NEUROL 2019.
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http://dx.doi.org/10.1002/ana.25492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6692656PMC
July 2019

Pearson Syndrome: A Rare Cause of Failure to Thrive in Infants.

Clin Pediatr (Phila) 2019 06 7;58(7):819-824. Epub 2019 Mar 7.

1 University Hospitals Cleveland Medical Center, Cleveland, OH, USA.

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http://dx.doi.org/10.1177/0009922819834285DOI Listing
June 2019

Enzymatic testing sensitivity, variability and practical diagnostic algorithm for pyruvate dehydrogenase complex (PDC) deficiency.

Mol Genet Metab 2017 11 8;122(3):61-66. Epub 2017 Sep 8.

Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Cleveland Medical Center (UHCMC), Cleveland, OH, USA; Department of Genetics and Genome Sciences, CWRU, Cleveland, OH, USA; Center for Human Genetics, UHCMC, Cleveland, OH, USA. Electronic address:

Pyruvate dehydrogenase complex (PDC) deficiency is a major cause of primary lactic acidemia in children. Prompt and correct diagnosis of PDC deficiency and differentiating between specific vs generalized, or secondary deficiencies has important implications for clinical management and therapeutic interventions. Both genetic and enzymatic testing approaches are being used in the diagnosis of PDC deficiency. However, the diagnostic efficacy of such testing approaches for individuals affected with PDC deficiency has not been systematically investigated in this disorder. We sought to evaluate the diagnostic sensitivity and variability of the various PDC enzyme assays in females and males at the Center for Inherited Disorders of Energy Metabolism (CIDEM). CIDEM data were filtered by lactic acidosis and functional PDC deficiency in at least one cell/tissue type (blood lymphocytes, cultured fibroblasts or skeletal muscle) identifying 186 subjects (51% male and 49% female), about half were genetically resolved with 78% of those determined to have a pathogenic PDHA1 mutation. Assaying PDC in cultured fibroblasts in cases where the underlying genetic etiology is PDHA1, was highly sensitive irrespective of gender; 97% (95% confidence interval [CI]: 90%-100%) and 91% (95% CI: 82%-100%) in females and males, respectively. In contrast to the fibroblast-based testing, the lymphocyte- and muscle-based testing were not sensitive (36% [95% CI: 11%-61%, p=0.0003] and 58% [95% CI: 30%-86%, p=0.014], respectively) for identifying known PDC deficient females with pathogenic PDHA1 mutations. In males with a known PDHA1 mutation, the sensitivity of the various cell/tissue assays (75% lymphocyte, 91% fibroblast and 88% muscle) were not statistically different, and the discordance frequency due to the specific cell/tissue used for assaying PDC was 0.15±0.11. Based on this data, a practical diagnostic algorithm is proposed accounting for current molecular approaches, enzyme testing sensitivity, and variability due to gender, cell/tissue type used for testing, and successive repeat testing.
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http://dx.doi.org/10.1016/j.ymgme.2017.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5722699PMC
November 2017

Lethal neonatal case and review of primary short-chain enoyl-CoA hydratase (SCEH) deficiency associated with secondary lymphocyte pyruvate dehydrogenase complex (PDC) deficiency.

Mol Genet Metab 2017 04 2;120(4):342-349. Epub 2017 Feb 2.

Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

Mutations in ECHS1 result in short-chain enoyl-CoA hydratase (SCEH) deficiency which mainly affects the catabolism of various amino acids, particularly valine. We describe a case compound heterozygous for ECHS1 mutations c.836T>C (novel) and c.8C>A identified by whole exome sequencing of proband and parents. SCEH deficiency was confirmed with very low SCEH activity in fibroblasts and nearly absent immunoreactivity of SCEH. The patient had a severe neonatal course with elevated blood and cerebrospinal fluid lactate and pyruvate concentrations, high plasma alanine and slightly low plasma cystine. 2-Methyl-2,3-dihydroxybutyric acid was markedly elevated as were metabolites of the three branched-chain α-ketoacids on urine organic acids analysis. These urine metabolites notably decreased when lactic acidosis decreased in blood. Lymphocyte pyruvate dehydrogenase complex (PDC) activity was deficient, but PDC and α-ketoglutarate dehydrogenase complex activities in cultured fibroblasts were normal. Oxidative phosphorylation analysis on intact digitonin-permeabilized fibroblasts was suggestive of slightly reduced PDC activity relative to control range in mitochondria. We reviewed 16 other cases with mutations in ECHS1 where PDC activity was also assayed in order to determine how common and generalized secondary PDC deficiency is associated with primary SCEH deficiency. For reasons that remain unexplained, we find that about half of cases with primary SCEH deficiency also exhibit secondary PDC deficiency. The patient died on day-of-life 39, prior to establishing his diagnosis, highlighting the importance of early and rapid neonatal diagnosis because of possible adverse effects of certain therapeutic interventions, such as administration of ketogenic diet, in this disorder. There is a need for better understanding of the pathogenic mechanisms and phenotypic variability in this relatively recently discovered disorder.
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http://dx.doi.org/10.1016/j.ymgme.2017.02.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5382105PMC
April 2017

Succinyl-CoA synthetase (SUCLA2) deficiency in two siblings with impaired activity of other mitochondrial oxidative enzymes in skeletal muscle without mitochondrial DNA depletion.

Mol Genet Metab 2017 03 12;120(3):213-222. Epub 2016 Nov 12.

Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA. Electronic address:

Mutations in SUCLA2 result in succinyl-CoA ligase (ATP-forming) or succinyl-CoA synthetase (ADP-forming) (A-SCS) deficiency, a mitochondrial tricarboxylic acid cycle disorder. The phenotype associated with this gene defect is largely encephalomyopathy. We describe two siblings compound heterozygous for SUCLA2 mutations, c.985A>G (p.M329V) and c.920C>T (p.A307V), with parents confirmed as carriers of each mutation. We developed a new LC-MS/MS based enzyme assay to demonstrate the decreased SCS activity in the siblings with this unique genotype. Both siblings shared bilateral progressive hearing loss, encephalopathy, global developmental delay, generalized myopathy, and dystonia with choreoathetosis. Prior to diagnosis and because of lactic acidosis and low activity of muscle pyruvate dehydrogenase complex (PDC), sibling 1 (S1) was placed on dichloroacetate, while sibling 2 (S2) was on a ketogenic diet. S1 developed severe cyclic vomiting refractory to therapy, while S2 developed Leigh syndrome, severe GI dysmotility, intermittent anemia, hypogammaglobulinemia and eventually succumbed to his disorder. The mitochondrial DNA contents in skeletal muscle (SM) were normal in both siblings. Pyruvate dehydrogenase complex, ketoglutarate dehydrogenase complex, and several mitochondrial electron transport chain (ETC) activities were low or at the low end of the reference range in frozen SM from S1 and/or S2. In contrast, activities of PDC, other mitochondrial enzymes of pyruvate metabolism, ETC and, integrated oxidative phosphorylation, in skin fibroblasts were not significantly impaired. Although we show that propionyl-CoA inhibits PDC, it does not appear to account for decreased PDC activity in SM. A better understanding of the mechanisms of phenotypic variability and the etiology for tissue-specific secondary deficiencies of mitochondrial enzymes of oxidative metabolism, and independently mitochondrial DNA depletion (common in other cases of A-SCS deficiency), is needed given the implications for control of lactic acidosis and possible clinical management.
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http://dx.doi.org/10.1016/j.ymgme.2016.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5346465PMC
March 2017

The M405V allele of the glutaryl-CoA dehydrogenase gene is an important marker for glutaric aciduria type I (GA-I) low excretors.

Mol Genet Metab 2016 09 1;119(1-2):50-6. Epub 2016 Jul 1.

Center for Human Genetics, University Hospitals Case Medical Center, Cleveland, OH, United States; Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, United States; Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, United States. Electronic address:

Glutaric aciduria type I (GA-I) is an autosomal recessive organic aciduria resulting from a functional deficiency of glutaryl-CoA dehydrogenase, encoded by GCDH. Two clinically indistinguishable diagnostic subgroups of GA-I are known; low and high excretors (LEs and HEs, respectively). Early medical and dietary interventions can result in significantly better outcomes and improved quality of life for patients with GA-I. We report on nine cases of GA-I LE patients all sharing the M405V allele with two cases missed by newborn screening (NBS) using tandem mass spectrometry (MS/MS). We describe a novel case with the known pathogenic M405V variant and a novel V133L variant, and present updated and previously unreported clinical, biochemical, functional and molecular data on eight other patients all sharing the M405V allele. Three of the nine patients are of African American ancestry, with two as siblings. GCDH activity was assayed in six of the nine patients and varied from 4 to 25% of the control mean. We support the use of urine glutarylcarnitine as a biochemical marker of GA-I by demonstrating that glutarylcarnitine is efficiently cleared by the kidney (50-90%) and that plasma and urine glutarylcarnitine follow a linear relationship. We report the allele frequencies for three known GA-I LE GCDH variants (M405V, V400M and R227P) and note that both the M405V and V400M variants are significantly more common in the population of African ancestry compared to the general population. This report highlights the M405V allele as another important molecular marker in patients with the GA-I LE phenotype. Therefore, the incorporation into newborn screening of molecular screening for the M405V and V400M variants in conjunction with MS/MS could help identify asymptomatic at-risk GA-I LE patients that could potentially be missed by current NBS programs.
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http://dx.doi.org/10.1016/j.ymgme.2016.06.012DOI Listing
September 2016

Novel SMC1A frameshift mutations in children with developmental delay and epilepsy.

Eur J Med Genet 2015 Oct 18;58(10):562-8. Epub 2015 Sep 18.

Center for Human Genetics, Departments of Genetics and Pediatrics, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA. Electronic address:

Cornelia de Lange syndrome (CdLS) is a rare dominantly inherited genetic multisystem developmental condition with considerable phenotypic and allelic heterogeneity. Missense and in-frame deletions within the SMC1A gene can be associated with epilepsy and milder craniofacial features. We report two females who presented with developmental delay and developed isolated medically refractory seizures with unrevealing initial laboratory, imaging and genetic evaluations. Whole exome sequencing (WES) analyses were performed and were instrumental in uncovering the genetic etiology for their conditions. WES identified two novel de novo heterozygous frameshift mutations in the SMC1A gene [c.2853_2856delTCAG (p.Ser951Argfs*12) and c.3549_3552dupGGCC (p.Ile1185Glyfs*23)]. We also observed marked skewing of X-inactivation in one patient. The individual with the p.Ser951Argfs*12 mutation represents an extreme on the CdLS phenotypic spectrum, with prominent neurological involvement of severe developmental delay and refractory epilepsy, with mild craniofacial features. Both individuals eventually had incomplete clinical responses to therapy with valproic acid. We review previous reports of SMC1A mutations with epilepsy. SMC1A should be included in clinical gene panels for early infantile and early childhood epileptic encephalopathy.
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http://dx.doi.org/10.1016/j.ejmg.2015.09.007DOI Listing
October 2015

Clinical and biochemical characterization of four patients with mutations in ECHS1.

Orphanet J Rare Dis 2015 Jun 18;10:79. Epub 2015 Jun 18.

Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands.

Background: Short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1) catalyzes hydration of 2-trans-enoyl-CoAs to 3(S)-hydroxy-acyl-CoAs. SCEH has a broad substrate specificity and is believed to play an important role in mitochondrial fatty acid oxidation and in the metabolism of branched-chain amino acids. Recently, the first patients with SCEH deficiency have been reported revealing only a defect in valine catabolism. We investigated the role of SCEH in fatty acid and branched-chain amino acid metabolism in four newly identified patients. In addition, because of the Leigh-like presentation, we studied enzymes involved in bioenergetics.

Methods: Metabolite, enzymatic, protein and genetic analyses were performed in four patients, including two siblings. Palmitate loading studies in fibroblasts were performed to study mitochondrial β-oxidation. In addition, enoyl-CoA hydratase activity was measured with crotonyl-CoA, methacrylyl-CoA, tiglyl-CoA and 3-methylcrotonyl-CoA both in fibroblasts and liver to further study the role of SCEH in different metabolic pathways. Analyses of pyruvate dehydrogenase and respiratory chain complexes were performed in multiple tissues of two patients.

Results: All patients were either homozygous or compound heterozygous for mutations in the ECHS1 gene, had markedly reduced SCEH enzymatic activity and protein level in fibroblasts. All patients presented with lactic acidosis. The first two patients presented with vacuolating leukoencephalopathy and basal ganglia abnormalities. The third patient showed a slow neurodegenerative condition with global brain atrophy and the fourth patient showed Leigh-like lesions with a single episode of metabolic acidosis. Clinical picture and metabolite analysis were not consistent with a mitochondrial fatty acid oxidation disorder, which was supported by the normal palmitate loading test in fibroblasts. Patient fibroblasts displayed deficient hydratase activity with different substrates tested. Pyruvate dehydrogenase activity was markedly reduced in particular in muscle from the most severely affected patients, which was caused by reduced expression of E2 protein, whereas E2 mRNA was increased.

Conclusions: Despite its activity towards substrates from different metabolic pathways, SCEH appears to be only crucial in valine metabolism, but not in isoleucine metabolism, and only of limited importance for mitochondrial fatty acid oxidation. In severely affected patients SCEH deficiency can cause a secondary pyruvate dehydrogenase deficiency contributing to the clinical presentation.
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http://dx.doi.org/10.1186/s13023-015-0290-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4474341PMC
June 2015

The Value of Comprehensive Thyroid Function Testing and Family History for Early Diagnosis of MCT8 Deficiency.

Clin Pediatr (Phila) 2016 Mar 29;55(3):286-9. Epub 2015 Apr 29.

Pediatric Neurology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA.

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http://dx.doi.org/10.1177/0009922815584219DOI Listing
March 2016

Somatic mosaicism for a novel mutation in a male with severe pyruvate dehydrogenase complex deficiency.

Mol Genet Metab Rep 2014 28;1:362-367. Epub 2014 Aug 28.

Center for Human Genetics Laboratory University Hospitals Case Medical Center, Cleveland, OH, USA.

Pyruvate dehydrogenase complex (PDC) deficiencies are mostly due to mutations in the X-linked gene. Males with hemizygous mutations are clinically more severely affected, while those with mosaic mutations may manifest milder phenotypes. We report a patient harboring a novel, mosaic missense mutation, c.523G > A (p.A175T), with a severe clinical presentation of congenital microcephaly, significant brain abnormalities, persistent seizures, profound developmental delay, and failure to thrive. We review published cases of mosaicism.
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http://dx.doi.org/10.1016/j.ymgmr.2014.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121365PMC
August 2014

Novel DICER1 mutation as cause of multinodular goiter in children.

Head Neck 2013 Dec 1;35(12):E369-71. Epub 2013 Jun 1.

Division of Pediatric Otolaryngology, Department of Otolaryngology-Head and Neck Surgery, University of Michigan Health System, Ann Arbor, Michigan.

Background: The aim of this report was to present a rare case of an adolescent with multinodular goiter (MNG) found to have a DICER1 mutation.

Methods And Results: The methodology includes a presentation and discussion of a chart review including endocrine hormone tests, thyroid ultrasound, and genetic testing for DICER1. A 12-year-old girl presented with a diffusely enlarged thyroid gland. Family history revealed an older sister with a history of bilateral ovarian Sertoli-Leydig cell tumors and MNG. Thyroid function tests were normal. Serial thyroid ultrasounds showed enlarging multiple bilateral nodules. Fine-needle aspiration suggested MNG. Genetic testing revealed a novel heterozygous premature termination mutation (c.1525C>T p.R509X) in the DICER1 gene.

Conclusions: Thyroid nodules are rare in children but carry a higher risk for malignancy. It is essential to inquire about family history and refer for genetic evaluation with a family history of MNG. In patients with DICER1 mutations, tumor surveillance is critical due to the increased risk of multiple tumors, including ovarian tumors and pleuropulmonary blastoma.
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http://dx.doi.org/10.1002/hed.23250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762914PMC
December 2013

Leigh syndrome in a girl with a novel DLD mutation causing E3 deficiency.

Pediatr Neurol 2013 Jan;48(1):67-72

Division of Genetics, Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA.

We present the biochemical and molecular diagnosis of dihydrolipoamide dehydrogenase deficiency (also known as E3 deficiency) and Leigh syndrome in a 14-year-old girl with learning disability and episodic encephalopathy and ketoacidosis. The diagnosis was based on values of plasma amino acids and urine organic acids, obtained during acute encephalopathy, lactic ketoacidosis, and liver failure, precipitated by infectious mononucleosis. Enzymatic and molecular analyses confirmed dihydrolipoamide dehydrogenase deficiency. E3 activity from cultured skin fibroblasts ranged from 9-29% of the mean. Molecular analysis revealed compound heterozygosity for novel and known pathogenic mutations (p.I353T and p.G136del, respectively). The patient received dietary augmentation and continuous renal replacement therapy, given her severe, persistent lactic acidosis. Acute decompensation resulted in magnetic resonance imaging changes involving the posterior aspect of the putamen, lateral, and medial thalami, substantia nigra, lateral geniculate bodies, and splenium of the corpus callosum. The cortex and subcortical white matter of the right and left occipital lobes and perirolandic region were also affected. In our review of molecularly confirmed patients with dihydrolipoamide dehydrogenase deficiency, Leigh syndrome was common. Our patient, whose most severe decompensation occurred at a more advanced age than previously reported, provides further evidence of the heterogeneous presentations of dihydrolipoamide dehydrogenase deficiency.
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http://dx.doi.org/10.1016/j.pediatrneurol.2012.09.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4535688PMC
January 2013

Age-related effect of serotonin transporter genotype on amygdala and prefrontal cortex function in adolescence.

Hum Brain Mapp 2014 Feb 5;35(2):646-58. Epub 2012 Nov 5.

Department of Psychology, University of Michigan, Ann Arbor, Michigan.

The S and LG alleles of the serotonin transporter-linked polymorphic region (5-HTTLPR) lower serotonin transporter expression. These low-expressing alleles are linked to increased risk for depression and brain activation patterns found in depression (increased amygdala activation and decreased amygdala-prefrontal cortex connectivity). Paradoxically, serotonin transporter blockade relieves depression symptoms. Rodent models suggest that decreased serotonin transporter in early life produces depression that emerges in adolescence, whereas decreased serotonin transporter that occurs later in development ameliorates depression. However, no brain imaging research has yet investigated the moderating influence of human development on the link between 5-HTTLPR and effect-related brain function. We investigated the age-related effect of 5-HTTLPR on amygdala activation and amygdala-prefrontal cortex connectivity using a well-replicated probe, an emotional face task, in children and adolescents aged 9-19 years. A significant genotype-by-age interaction predicted amygdala activation, such that the low-expressing genotype (S/S and S/LG ) group showed a greater increase in amygdala activation with age compared to the higher expressing (LA /LA and S/LA ) group. Additionally, compared to the higher expressing group, the low-expressing genotype group exhibited decreased connectivity between the right amygdala and ventromedial prefrontal cortex with age. Findings indicate that low-expressing genotypes may not result in the corticolimbic profile associated with depression risk until later adolescence.
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http://dx.doi.org/10.1002/hbm.22208DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4164216PMC
February 2014

The impact of serotonin transporter genotype on default network connectivity in children and adolescents with autism spectrum disorders.

Neuroimage Clin 2012 7;2:17-24. Epub 2012 Nov 7.

Department of Psychology, University of Michigan, 530 Church St., Ann Arbor, MI 48109, USA.

Compared to healthy controls, individuals with autism spectrum disorders (ASD) have weaker posterior-anterior connectivity that strengthens less with age within the default network, a set of brain structures connected in the absence of a task and likely involved in social function. The serotonin transporter-linked polymorphic region (5-HTTLPR) genotypes that result in lowered serotonin transporter expression are associated with social impairment in ASD. Additionally, in healthy controls, low expressing 5-HTTLPR genotypes are associated with weaker default network connectivity. However, in ASD, the effect of 5-HTTLPR on the default network is unknown. We hypothesized that 5-HTTLPR's influence on posterior-anterior default network connectivity strength as well as on age-related changes in connectivity differs in the ASD group versus controls. Youth with ASD and healthy controls, ages 8-19, underwent a resting fMRI acquisition. Connectivity was calculated by correlating the posterior hub of the default network with all voxels. Triallelic genotype was assessed via PCR and Sanger sequencing. A genotype-by-diagnosis interaction significantly predicted posterior-anterior connectivity, such that low expressing genotypes (S/S, S/LG, LG/LG) were associated with stronger connectivity than high expressing genotypes (LA/LA, S/LA, LA/LG) in the ASD group, but the converse was true for controls. Also, youth with ASD and low expressing genotypes had greater age-related increases in connectivity values compared to those with high expressing genotypes and controls in either genotype group. Our findings suggest that the cascade of events from genetic variation to brain function differs in ASD. Also, low expressing genotypes may represent a subtype within ASD.
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http://dx.doi.org/10.1016/j.nicl.2012.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3777679PMC
November 2013

The impact of serotonin transporter (5-HTTLPR) genotype on the development of resting-state functional connectivity in children and adolescents: a preliminary report.

Neuroimage 2012 Feb 18;59(3):2760-70. Epub 2011 Oct 18.

Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA.

A fundamental component of brain development is the formation of large-scale networks across the cortex. One such network, the default network, undergoes a protracted development, displaying weak connectivity in childhood that strengthens in adolescence and becomes most robust in adulthood. Little is known about the genetic contributions to default network connectivity in adulthood or during development. Alterations in connectivity between posterior and frontal portions of the default network have been associated with several psychological disorders, including anxiety, autism spectrum disorders, schizophrenia, depression, and attention-deficit/hyperactivity disorder. These disorders have also been linked to variants of the serotonin transporter linked polymorphic region (5-HTTLPR). The LA allele of 5-HTTLPR results in higher serotonin transporter expression than the S allele or the rarer LG allele. 5-HTTLPR may influence default network connectivity, as the superior medial frontal region has been shown to be sensitive to changes in serotonin. Also, serotonin as a growth factor early in development may alter large-scale networks such as the default network. The present study examined the influence of 5-HTTLPR variants on connectivity between the posterior and frontal structures and its development in a cross-sectional study of 39 healthy children and adolescents. We found that children and adolescents homozygous for the S allele (S/S, n=10) showed weaker connectivity in the superior medial frontal cortex compared to those homozygous for the LA allele (LA/LA, n=13) or heterozygotes (S/LA, S/LG, n=16). Moreover, there was an age-by-genotype interaction, such that those with LA/LA genotype had the steepest age-related increase in connectivity between the posterior hub and superior medial frontal cortex, followed by heterozygotes. In contrast, individuals with the S/S genotype had the least age-related increase in connectivity strength. This preliminary report expands our understanding of the genetic influences on the development of large-scale brain connectivity and lays down the foundation for future research and replication of the results with a larger sample.
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http://dx.doi.org/10.1016/j.neuroimage.2011.10.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3254835PMC
February 2012

Microarray oligonucleotide probe designer (MOPeD): A web service.

Open Access Bioinformatics 2010 Nov;2(2010):145-155

Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA.

Methods of genomic selection that combine high-density oligonucleotide microarrays with next-generation DNA sequencing allow investigators to characterize genomic variation in selected portions of complex eukaryotic genomes. Yet choosing which specific oligonucleotides to be use can pose a major technical challenge. To address this issue, we have developed a software package called MOPeD (Microarray Oligonucleotide Probe Designer), which automates the process of designing genomic selection microarrays. This web-based software allows individual investigators to design custom genomic selection microarrays optimized for synthesis with Roche NimbleGen's maskless photolithography. Design parameters include uniqueness of the probe sequences, melting temperature, hairpin formation, and the presence of single nucleotide polymorphisms. We generated probe databases for the human, mouse, and rhesus macaque genomes and conducted experimental validation of MOPeD-designed microarrays in human samples by sequencing the human X chromosome exome, where relevant sequence metrics indicated superior performance relative to a microarray designed by the Roche NimbleGen proprietary algorithm. We also performed validation in the mouse to identify known mutations contained within a 487-kb region from mouse chromosome 16, the mouse chromosome 16 exome (1.7 Mb), and the mouse chromosome 12 exome (3.3 Mb). Our results suggest that the open source MOPeD software package and website (http://moped.genetics.emory.edu/) will make a valuable resource for investigators in their sequence-based studies of complex eukaryotic genomes.
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http://dx.doi.org/10.2147/OAB.S13741DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3048354PMC
November 2010

A complex 6p25 rearrangement in a child with multiple epiphyseal dysplasia.

Am J Med Genet A 2011 Jan 10;155A(1):154-63. Epub 2010 Dec 10.

Department of Pediatrics, The University of Michigan Medical School, Ann Arbor, USA.

Genomic rearrangements are increasingly recognized as important contributors to human disease. Here we report on an 11½-year-old child with myopia, Duane retraction syndrome, bilateral mixed hearing loss, skeletal anomalies including multiple epiphyseal dysplasia, and global developmental delay, and a complex 6p25 genomic rearrangement. We have employed oligonucleotide-based comparative genomic hybridization arrays (aCGH) of different resolutions (44 and 244K) as well as a 1 M single nucleotide polymorphism (SNP) array to analyze this complex rearrangement. Our analyses reveal a complex rearrangement involving a ∼2.21 Mb interstitial deletion, a ∼240 kb terminal deletion, and a 70-80 kb region in between these two deletions that shows maintenance of genomic copy number. The interstitial deletion contains eight known genes, including three Forkhead box containing (FOX) transcription factors (FOXQ1, FOXF2, and FOXC1). The region maintaining genomic copy number partly overlaps the dual specificity protein phosphatase 22 (DUSP22) gene. Array analyses suggest a homozygous loss of genomic material at the 5' end of DUSP22, which was corroborated using TaqMan® copy number analysis. It is possible that this homozygous genomic loss may render both copies of DUSP22 or its products non-functional. Our analysis suggests a rearrangement mechanism distinct from a previously reported replication-based error-prone mechanism without template switching for a specific 6p25 rearrangement with a 1.22 Mb interstitial deletion. Our study demonstrates the utility and limitations of using oligonucleotide-based aCGH and SNP array technologies of increasing resolutions in order to identify complex DNA rearrangements and gene disruptions.
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http://dx.doi.org/10.1002/ajmg.a.33751DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4533830PMC
January 2011

Duplication 16p11.2 in a child with infantile seizure disorder.

Am J Med Genet A 2010 Jun;152A(6):1567-74

Department of Pediatrics, The University of Michigan, Ann Arbor, Michigan 48109-5652, USA.

Submicroscopic recurrent 16p11.2 rearrangements are associated with several neurodevelopmental disorders, including autism, mental retardation, and schizophrenia. The common 16p11.2 region includes 24 known genes, of which 22 are expressed in the developing human fetal nervous system. As yet, the mechanisms leading to neurodevelopmental abnormalities and the broader phenotypes associated with deletion or duplication of 16p11.2 have not been clarified. Here we report a child with spastic quadriparesis, refractory infantile seizures, severe global developmental delay, hypotonia, and microcephaly, and a de novo 598 kb 16p11.2 microduplication. Family history is negative for any of these features in parents and immediate family members. Sequencing analyses showed no mutations in DOC2A, QPRT, and SEZ6L2, genes within the duplicated 16p11.2 region that have been implicated in neuronal function and/or seizure related phenotypes. The child's clinical course is consistent with a rare seizure disorder called malignant migrating partial seizure disorder of infancy, raising the possibility that duplication or disruption of genes in the 16p11.2 interval may contribute to this severe disorder.
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http://dx.doi.org/10.1002/ajmg.a.33415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160635PMC
June 2010

First case of deletion of the faciogenital dysplasia 1 (FGD1) gene in a patient with Aarskog-Scott syndrome.

Eur J Med Genet 2009 Jul-Aug;52(4):262-4. Epub 2008 Dec 16.

Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI 48109-5718, USA.

Mutations within the faciogenital dysplasia 1 (FGD1) gene in individuals with clinical features of Aarskog-Scott syndrome (AAS) include missense mutations and insertions and deletions that result in frameshifts and premature terminations. Whole gene deletion and duplication represent other mutational possibilities not yet reported for FGD1 but known to exist for other genes such as MECP2. We report the first case of a boy with clinical features of AAS with deletion of FGD1 gene identified using an oligonucleotide-based X chromosome-specific microarray after attempts to generate amplicons for all of the FGD1 coding exons failed and BAC microarray analysis showed no abnormality.
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http://dx.doi.org/10.1016/j.ejmg.2008.12.001DOI Listing
November 2009

Branchiootorenal syndrome and oculoauriculovertebral spectrum features associated with duplication of SIX1, SIX6, and OTX2 resulting from a complex chromosomal rearrangement.

Am J Med Genet A 2008 Oct;146A(19):2480-9

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.

We report on a 26-month-old boy with developmental delay and multiple congenital anomalies, including many features suggestive of either branchiootorenal syndrome (BOR) or oculoauriculovertebral spectrum (OAVS). Chromosomal microarray analysis (CMA) initially revealed a copy-number gain with a single BAC clone (RP11-79M1) mapping to 14q23.1. FISH analysis showed that the third copy of this genomic region was inserted into the long arm of one chromosome 13. The same pattern was also seen in the chromosomes of the father, who has mental retardation, short stature, hypernasal speech, and minor craniofacial anomalies, including tall forehead, and crowded dentition. Subsequent whole genome oligonucleotide microarray analysis revealed an approximately 11.79 Mb duplication of chromosome 14q22.3-q23.3 and a loss of an approximately 4.38 Mb sequence in 13q21.31-q21.32 in both the propositus and his father and FISH supported the apparent association of the two events. Chromosome 14q22.3-q23.3 contains 51 genes, including SIX1, SIX6, and OTX2. A locus for branchiootic syndrome (BOS) has been mapped to 14q21.3-q24.3, and designated as branchiootic syndrome 3 (BOS3). Interestingly, mutations in SIX1 have been reported in patients with BOR/BOS3. We propose that the increased dosage of SIX1, SIX6, or OTX2 may be responsible for the BOR and OAVS-like features in this family.
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http://dx.doi.org/10.1002/ajmg.a.32398DOI Listing
October 2008

Transmission of ring chromosome 13 from a mother to daughter with both having a 46,XX, r(13)(p13q34) karyotype.

Am J Med Genet A 2004 Sep;129A(3):316-20

Department of Genetic and Metabolic Disorders, Children's Hospital of Michigan, Detroit, Michigan 48201, USA.

Ring chromosomes are thought to be the result of breakage in both arms of a chromosome, with fusion of the points of fracture and loss of the distal fragments. Another mechanism of ring formation is believed to be the simple fusion of chromosome ends with preservation of telomeric and subtelomeric sequences. Ring chromosome 13 was first described in 1968 and its incidence estimated at 1 in 58,000 live births. Severe phenotypes associated with large deletions of 13q have been described as "ring chromosome 13 syndrome." Features of the "ring chromosome 13 syndrome" include mental retardation (often severe), growth retardation, microcephaly, facial dysmorphism, and hand, foot or toe abnormalities. We report on a case of a mother and daughter with r(13) and mild phenotypes. Our patient, IA, had chromosome analysis performed at about 4(1/2) years of age due to some developmental delay. This revealed 46,XX, r(13)(p13q34) karyotype with no loss of any chromosomal band. Her mother, EA, was subsequently found to have the same ring 13. IA's maternal grandmother had a normal karyotype while her maternal grandfather was unavailable for testing. Fluorescence in situ hybridization (FISH) analysis showed loss of a specific subtelomeric 13q region in r(13) in the mother. Clinically, IA had macular hyperpigmentation on the chin and mild delay in speech and fine motor skills. EA, 22 years of age, had mild short stature and borderline mental retardation. To our knowledge, this is the first report of a case of familial transmission of r(13). We compare phenotypes of our cases with those from other reported cases of r(13) and discuss the possible mechanism of formation of this ring chromosome.
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http://dx.doi.org/10.1002/ajmg.a.30242DOI Listing
September 2004