Citrullinemia is an inherited disorder that causes ammonia and other toxic substances to accumulate in the blood. Two types of citrullinemia have been described; they have different signs and symptoms and are caused by mutations in different genes.

Mutations in the ASS1 and SLC25A13 genes cause citrullinemia. The proteins produced from these genes play roles in the urea cycle. The urea cycle is a sequence of chemical reactions that takes place in liver cells. These reactions process excess nitrogen that is generated when protein is used by the body. The excess nitrogen is used to make a compound called urea, which is excreted in urine.

Type I citrullinemia is the most common form of the disorder, affecting about 1 in 57,000 people worldwide. Type II citrullinemia is found primarily in the Japanese population, where it occurs in an estimated 1 in 100,000 to 230,000 individuals. Type II also has been reported in other populations, including other people from East Asia, the Middle East, the United States, and the United Kingdom.

Both types of citrullinemia are inherited in an autosomal recessive pattern, which means both copies of the respective 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: May 01, 2017Published By: National Institutes of Health