Rare autosomal recessive disorder of the urea cycle; caused by a deficiency of the hepatic enzyme type i arginase; arginine is elevated in the blood and cerebrospinal fluid, and periodic hyperammonemia may occur; disease onset is usually in infancy or early childhood; clinical manifestations include seizures, microcephaly, progressive mental impairment, hypotonia, ataxia, spastic diplegia, and quadriparesis.

Argininemia is an autosomal recessive urea cycle disorder where a deficiency of the enzyme arginase causes a buildup of arginine and ammonia in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if levels become too high; the nervous system is especially sensitive to the effects of excess ammonia..