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Citrullinemia type I

Other Names for this Disease
  • Argininosuccinate synthetase deficiency
  • ASS deficiency
  • Citrullinemia 1
  • Citrullinuria
  • Classic citrullinemia
More Names
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What are the symptoms of citrullinemia type I?

Citrullinemia type I presents as a clinical spectrum that includes an acute neonatal form, a milder late-onset form, a form without symptoms and/or hyperammonemia, and a form in which women have onset of severe symptoms during pregnancy or post partum.[1] Infants with the acute neonatal form typically appear normal at birth, but as ammonia builds up in the body they become progressively lethargic, feed poorly, vomit, and develop signs of increased intracranial pressure, which can lead to seizures and loss of consciousness.[2][1] Less commonly, a milder form of citrullinemia type I can develop later in childhood or adulthood. This later-onset form is associated with intense headaches, partial loss of vision, slurred speech, problems with balance and muscle coordination (ataxia), behavior problems, and lethargy.[2][3] Episodes of high blood ammonia often happen after going without food for long periods of time, during illness or infection or after high-protein meals.[3] Some people with gene mutations that cause citrullinemia type I never experience signs and symptoms of the disorder and are only found to be affected after a brother or sister is diagnosed.[2][3]
Last updated: 4/20/2010

  1. Thoene JG. Citrullinemia Type I. GeneReviews. 2009; Accessed 4/20/2010.
  2. Citrullinemia. Genetics Home Reference (GHR). 2006; Accessed 7/11/2011.
  3. Citrullinemia. Screening, Technology and Research in Genetics (STAR-G). 2007; Accessed 4/20/2010.