OTC is a member of the ATCase/OTCase family. OTC has a key part in the urea cycle， catalyzing the second step in this pathway: the transformation of L-orthinine and carbamoyl phosphate to L-citrulline. In humans， the urea cycle is a vital pathway to detoxification of ammonia. Alterations in the gene encoding OTC are linked to the X-linked disorder OTCD（ornithine carbamoyltransferase deficiency). OTCD disorder of the urea cycle is characterized by hyperammonemia.
