Living donor liver transplantation for type II citrullinemia from a heterozygous donor

Adult-onset type II citrullinemia (CTLN2) is a rare disorder of the urea cycle resulting in hyperammonemia, with a poor prognosis. Here we report a 48-year-old Japanese man who showed abnormal nocturnal behavior. Laboratory data indicated raised plasma concentrations of ammonia and citrulline, and a definitive diagnosis of CTLN2 was made by DNA analysis. Hyperammonemia was not improved by oral intake of branched-chain amino acids (BCAA), whereas venous infusion of BCAA was effective. Western blotting revealed heterozygotic expression of citrin protein in a liver biopsy specimen from the patient's brother. However, as symptomatic CTLN2 is very unusual in a heterozygotic carrier, we considered the brother suitable as a living-donor liver transplantation (LDLT) donor. The recipient's entire liver was removed, and replaced with the left liver graft. The plasma ammonia level remained low without infusion of BCAA after liver transplantation. From this case we conclude that venous infusion, rather than oral administration, of BCAA is useful for conservative treatment of CTLN2. However, liver transplantation is the only effective therapeutic option for CTLN2, and should be performed before irreversible encephalopathy occurs. Use of a graft from heterozygotic donors is permissible treatment for CTLN2.