argininosuccinic aciduriamedical dictionary

<biochemistry> Argininosuccinic aciduria, an autosomal recessive defect of the urea cycle, is due to deficiency of argininosuccinate lyase (argininosuccinase), which catalyses the hydrolysis of argininosuccinic acid to arginine and fumaric acid.

It is characterised by excessive urinary excretion of argininosuccinic acid, epilepsy, ataxia, mental retardation, liver disease, and friable, tufted hair; presumed to be the consequence of a deficiency of an enzyme responsible for splitting argininosuccinic acid to arginine and fumaric acid.

Argininosuccinase is a cytosolic enzyme found in highest amounts in the liver. Like the other urea cycle defects except for arginase deficiency, argininosuccinic aciduria typically presents early in the neonatal period with serious, often fatal, hyperammonaemia and residual neurologic damage.

Argininosuccinic acid is found in high concentrations in plasma and urine by amino acid chromatography. It can also be detected in amniotic fluid for purposes of prenatal diagnosis. Diagnosis is confirmed by specific enzyme assay.

The argininosuccinase gene has been cloned and is found on chromosome 7.

Inheritance: autosomal recessive.

Acronym: ASA

(05 Mar 2000)