Current Treatment Modalities for Urea Cycle Disorders

The urea cycle, a metabolic pathway comprising six enzymes and two transporters, is necessary for mammalian nitrogen detoxification. A deficiency of any of these components disrupts this process, leading to the accumulation of nitrogen in the form of ammonia, which is especially toxic to the brain. For decades, treatment of urea cycle disorders has consisted of nitrogen scavengers, dietary protein restriction, arginine or citrulline supplementation, calorie support, and liver transplant. In 2011, carglumic acid became available as a substitute for N-acetylglutamate for N-acetylglutamate synthase deficiency. The past 10 years, however, have seen the development of enzyme therapy for arginase deficiency and gene therapy for ornithine transcarbamylase deficiency. This article reviews the current status and availability of treatment options for urea cycle disorders.