OTC, also called ornithine carbamoyltransferase, belongs to the ATCase/OTCase family. OTC plays a vital role in the urea cycle, catalyzing the second step in this pathway: the formation of L-citrulline from L-orthinine and carbamoyl phosphate. In humans, the urea cycle is an important pathway to detoxification of ammonia. Mutations in the gene encoding OTC are associated with the X-linked disorder OTCD (ornithine carbamoyltransferase deficiency).