Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ornithine transcarbamylase deficiency is an X-linked recessive disorder of urea biosynthesis characterized by recurrent, often fatal, hyperammonemic encephalopathy in affected males; carrier females are usually asymptomatic. We report here the clinical and laboratory findings in five symptomatic heterozygous females with ornithine transcarbamylase deficiency. In each case, the onset of symptoms occurred in the 1st year of life, but diagnosis was delayed by up to 15 years. Symptoms included recurrent vomiting with lethargy (five patients), dietary protein intolerance (five), irritability (four), severe acute encephalopathy (three), ataxia (three), and acute hemiparesis (two). All eventually showed evidence of developmental delay or learning difficulties. Two of the three who experienced severe, acute, hyperammonemic encephalopathy suffered serious, permanent neurologic sequelae. Three of the patients showed decreased ornithine transcarbamylase activity in liver obtained by needle biopsy, and the other two had marked orotic aciduria associated with hyperammonemia. Neuroimaging studies demonstrated persistent abnormal lobar attenuation and abnormal signal on computed tomographic scan and magnetic resonance imaging. All patients showed marked symptomatic improvement on treatment with dietary protein restriction supplemented by pharmacologic measures to increase nonprotein nitrogen excretion. Ornithine transcarbamylase deficiency should be considered in the differential diagnosis of acute or chronic encephalopathy in females at any age.
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PMID:Ornithine transcarbamylase deficiency in females: an often overlooked cause of treatable encephalopathy. 749 56

Late-onset urea cycle disorder in a 20-month-old boy is unusually associated with Klinefelter syndrome with a 47XXY karyotype. We record the typical clinical and biochemical findings of ornithine transcarbamylase (OTC) deficiency in a young boy with a short history of recurrent vomiting, self mutilating behaviour, lethargy, ataxia and seizures. Laboratory studies showed hyperammonaemia and orotic aciduria, with normal citrulline and other urea cycle amino acids. Unfortunately, a liver biopsy for OTC activity measurement was refused by the parents. A rapid reversal of phenotype was seen on the introduction of a low-protein diet with accompanying benzoate and phenylbutyrate administration. Linkage studies suggested the inheritance of two X chromosomes, which was confirmed by karyotype analysis. Sequencing of all exons and immediate splice site regions revealed no sequence alterations in these sections of the OTC gene. A search for skewing of X-inactivation in the liver was not possible but we did show a random pattern of X-inactivation in leukocytes. The possibility of maternal X chromosome iso-disomy in our patient was discounted by microsatellite analysis, which revealed the inheritance of two independent X chromosomes. Mutation analysis in the OTC gene has shown that approximately 20% of patients with liver biopsy confirmed OTC deficiency do not have mutations in the coding or immediate splice-site sequences of this gene. Their classification as OTC phenocopies remains speculative, awaiting clarification of the underlying DNA alteration. We report on the novel association of OTC deficiency and Klinefelter syndrome with the additional interest of a probable unusual genetic defect underlying the OTC abnormality.
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PMID:An OTC deficiency 'phenocopy' in association with Klinefelter syndrome. 1718 14