carbamoylphosphate synthetase deficiencymedical dictionary

<biochemistry> Carbamoylphosphate synthetase is the initial enzyme of the urea cycle, catalysing the synthesis of carbamoylphosphate from ammonia, bicarbonate and ATP as the first step of ammonia detoxification.

The enzyme is an intramitochondrial form called CPS I. A different isozyme found in the cytoplasm, called CPS II, is much less active and apparently not involved in the urea cycle. The deficiency state is autosomal recessive and presents in infancy with massive hyperammonaemia and neurologic deficits in survivors.

Diagnosis is suggested by the blood biochemistry and confirmed by specific enzyme assay on liver or rectal biopsy. Prenatal diagnosis by molecular methods has been used successfully in informative families.

Inheritance: autosomal recessive.

(07 Apr 1998)