citrullinemia type II

a condition caused by mutations in the SLC25A13 gene (locus: 7q21.3), which encodes a mitochondrial transport protein necessary for the conversion of citrulline to argininoscuccinic acid. It is seen almost exclusively in Japan and exists in two forms. The neonatal form is generally self-limited and characterized by fatty infiltration and moderate fibrosis of the liver, cholestatic jaundice, hyperbilirubinemia, hypoproteinemia, and clotting dysfunction; serum ammonia and citrulline levels are usually normal. The adult-onset form appears between 20 and 40 years of age and is manifested by neuropsychiatric symptoms, with moderate elevation of serum ammonia and citrulline.