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GTR Home > Conditions/Phenotypes > Ornithine carbamoyltransferase deficiency


Excerpted from the GeneReview: Ornithine Transcarbamylase Deficiency
Ornithine transcarbamylase (OTC) deficiency can occur as a severe neonatal-onset disease in males (but rarely in females) and as a post-neonatal-onset (also known as "late-onset" or partial deficiency) disease in males and females. Males with severe neonatal-onset OTC deficiency are asymptomatic at birth but become symptomatic from hyperammonemia in the first week of life, most often on day two to three of life, and are usually catastrophically ill by the time they come to medical attention. After successful treatment of neonatal hyperammonemic coma these infants can easily become hyperammonemic again despite appropriate treatment; they typically require liver transplant to improve quality of life. Males and heterozygous females with post-neonatal-onset (partial) OTC deficiency can present from infancy to later childhood, adolescence, or adulthood. No matter how mild the disease, a hyperammonemic crisis can be precipitated by stressors and become a life-threatening event at any age and in any situation in life. For all individuals with OTC deficiency, typical neuropsychological complications include developmental delay, learning disabilities, intellectual disability, attention-deficit/hyperactivity disorder, and executive function deficits.

Genes See tests for all associated and related genes

  • Also known as: OCTD, OTC1, OTCD, OTCase, OTC
    Summary: ornithine transcarbamylase

Clinical features


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Practice guidelines

  • ACMG ACT, 2022
    American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, Decreased Citrulline, 2022
  • ACMG Algorithm, 2022
    American College of Medical Genetics and Genomics, Algorithm, Decreased Citrulline, 2022
  • ACMG ACT, 2012
    American College of Medical Genetics and Genomics, Transition to Adult Health Care ACT Sheet, Ornithine Transcarbamylase (OTC) deficiency, 2012

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