Argininosuccinate

- Plasma: Increased concentration of argininosuccinic acid is the biomarker that distinguishes argininosucciniate lyse deficiency from other urea cycle disorders.

- Argininosuccinic Aciduria: Argininosuccinic aciduria derives its name from the marked elevation of argininosuccinic acid in the blood and urine of affected persons. In the severe forms, this disorder can present with hyperammonemic coma in the newborn period, whereas those with mild forms have fewer, if any, episodes of symptomatic hyperammonemia [Nagamani, Erez, and Lee, 2011(L)].

- For ASL deficiency, there is accumulation of argininosuccinic acid that is damaging to all organs and may result in intellectual disability and psychiatric symptoms, as well as abnormal hair, hepatomegaly, and hepatic fibrosis, which are unique features of this disorder.

Argininosuccinate (aka Arginosuccinic acid) is a basic amino acid. Some cells synthesize it from citrulline, aspartic acid and use it as a precursor for arginine in the urea cycle or Citrulline-NO cycle. The enzyme that catalyzes the reaction is argininosuccinate synthetase. Argininosuccinic acid is a precursor to fumarate in the citric acid cycle via argininosuccinate lyase. Defects in the argininosuccinate lyase enzyme can lead to argininosuccinate lyase deficiency, which is an inborn error of metabolism.