Ornithine transcarbamylase deficiency (OTCD), the most common of the urea cycle disorders, is a rare metabolic disorder, occurring in one out of every 80,000 births. OTCD is a genetic disorder resulting in a mutated and ineffective form of the enzyme ornithine transcarbamylase. Symptoms Like other urea cycle disorders, OTC affects the body's ability to get rid of ammonia, a toxic breakdown product of the body's use of protein. As a result, ammonia accumulates in the blood causing hyperammonemia. This ammonia travels to the various organs of the body. Genetics Treatment