Hyperammonemic Encephalopathy Caused by the c.386+5G>A Mutation in OTC Gene in a Young Adult Woman

Noncirrhotic hyperammonemia as a cause of acute confusion remains diagnostic challenge. Deficiency of ornithine transcarbamylase (OTC) is the urea cycle disorder, inborn errors caused by a defect of the enzymes in the urea cycle, leading to an accumulation of ammonia mainly in newborn. There were very few cases, in which OTC deficiency result in hyperammonemia in adulthood. Herein, we report a young adult woman of hyperammonemic encephalopathy with OTC deficiency, diagnosed by high blood ammonia, glutamine and low plasma levels of citrulline. Next generation sequencing showed the c.386+5G>A mutation of the OTC gene.