Carbamoyl Phosphate Synthetase I Deficiency (CPSID) is a rare autosomal recessive disorder that is strictly limited to the liver and intestine, and results in congenital hyperammonemia and defective citrulline synthesis. The management of CPSID may include a strict lifelong diet of very limited protein intake, citrulline and arginine supplementation, and administration of both sodium benzoate and sodium phenylbutyrate.
Granot et al. (1986) reported an Arab child in whom the diagnosis of partial CPS deficiency was first made when she presented at nine years of age with hyperammonemic coma simulating Reye syndrome. Despite intensive therapy directed toward lowering of ammonia levels, she sustained irreversible brain damage.
Al-Shamsi et al. (2014) calculated the birth prevalence of CPSID at less than 0.98 per 100,000 live births.