Argininosuccinic aciduria is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

Mutations in the ASL gene cause argininosuccinic aciduria. This condition belongs to a class of genetic diseases called urea cycle disorders because they are caused by problems with a process in the body called the urea cycle. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle breaks down excess nitrogen, which is made when protein is used by the body, to make a compound called urea. Urea is removed from the body in urine. Breaking down excess nitrogen and excreting it as urea prevents it from accumulating in the body as ammonia.

Argininosuccinic aciduria occurs in approximately 1 in 70,000 to 218,000 newborns. Most cases of this condition are detected shortly after birth by newborn screening.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Published Date: March 01, 2020Published By: National Institutes of Health