UCD.- Carbamoyl phosphate synthetase (CPS) deficiency Childhood or late form.
Incidence
Autosomal recessive. Relatively rare.
Clinical Characteristics
Carbamyl phosphate synthetase deficiency is transmited as an autosomal recessive trait, the expression of which is strictly limited to the liver and intestin. it causes congenital hyperammonemia and defective citrulline synthesis. Onset usually occurs during infancy with hyperammonemic coma which may be associated with ketoacidosis, or more seldom during childhood with recurrent hyperammonemic coma or chronic vomiting, strong dislike of proteins, hypotonia, mental retardation, and growth failure. Granot et al. (1986) reported an Arab child in whom the diagnosis of partial CPS deficiency was first made when she presented at 9 years of age with hyperammonemic coma simulating Reye syndrome. Despite intensive therapy directed toward lowering of ammonia levels, she sustained irreversible brain damage. Diagnosis is suggested by hyperammonemia, high plasmatic glutamine, and low citrulline levels. Confirmation is obtained from enzymatic activity measured in a liver or intestinal biopsy. Patients are treated with a strict, lifelong diet of very limited protein intake, citrulline and arginine supplementation, and both sodium benzoate and sodium phenylbutyrate. Antenatal diagnosis is feasible, provided that the mutation has been identified.
Precipitants
Protein intake. Minor stresses may induce severe exacerbations.
Provocation Tests
Protein intake induce hyperammonemia.
Diagnostic Procedures
EB-L. Diagnosis is suggested by hyperammonemia, high plasmatic glutamine, and low citrulline levels. Confirmation is obtained from enzymatic activity measured in a liver or intestinal biopsy.