This article includes discussion of argininosuccinic acidemia, argininosuccinase deficiency, and argininosuccinic aciduria. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Argininosuccinic aciduria is an inherited urea cycle disorder caused by argininosuccinic acid lyase deficiency. Patients can present with hyperammonemic encephalopathy at any age, resulting in brain damage or even death if treatment is inadequate or delayed. Patients may also develop hepatomegaly, progressive liver fibrosis, and liver function abnormalities, but they can also present with intellectual disabilities only. The disease can be detected by tandem mass spectrometry-based newborn screening. Treatment consists of low-protein diet, nitrogen scavengers, and L-arginine. Liver transplantation prevents the production of toxic metabolites in the liver, but not in nonhepatic tissues. The authors discuss a novel model that predicts clinical severity using the in vitro residual enzyme activity of argininosuccinate lyase as biomarker.
Historical note and terminology
Argininosuccinic acidemia was first described in 1958 by Allan and colleagues (02). Its name derives from the marked elevation of argininosuccinic acid in blood of affected individuals. This disorder has also been called argininosuccinic aciduria because of the increased excretion of argininosuccinic acid in urine, and argininosuccinate lyase deficiency to denote its enzyme deficiency.