Carbamoyl Phosphate Synthase Ammonia Deficiency Disease (CPSAD) is a rare genetic disorder that affects the metabolism of ammonia. CPSAD is a mouthful of words, but it is important to understand its synonyms as well. Health professionals may refer to it as CPS Ammonia Deficiency Disease or simply CPSAD. The condition can also be called Carbamoyl Phosphate Synthetase I Deficiency Disease or CPS I Deficiency. Regardless of the name used, CPSAD is characterized by a deficiency in the enzyme carbamoyl phosphate synthase, which leads to the accumulation of toxic levels of ammonia in the body. Early diagnosis and treatment are crucial for individuals affected by this condition.