描述
Citrullinemia Type I, (Argininosuccinate Synthetase Deficiency, Citrullinuria, Citrullinemia, ASS) is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood. Two forms of citrullinemia have been described, both having different signs and symptoms, and are caused by mutations in different genes. Citrullinemia belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of chemical reactions that takes place in the liver. These reactions process excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys. Citrullinemia Type I is an autosomal recessive disease caused by mutation in the ASS gene which codes for argininosuccinate synthetase. A deficiency in this enzyme results in accumulation of citruilline as well as glycine and orotic acid in urine. Infants appear normal at birth, but within the first week of life symptoms such as feeding difficulties, irritability, hypotonia, seizures, and vomiting present and eventually lead to premature death.