ABSTRACT
Typical neonatal hyperammonemic crisis, hyperglutaminemia, hypocitrullinemia, and absence of activity of hepatic carbamylphosphate synthetase are the major phenotypic expression. Transcription of the gene takes place in the nucleus. The carbamylphosphate synthetase (CPS) mRNA is essentially found only in the liver, but enzyme activity has been demonstrated in intestinal mucosa. Usually, the infant is normal at birth and may do well for a short period, often until feedings begin. Then failure to feed well and lethargy develop. There may be grunting or rapid respiration, hypotonia or hypertonia, convulsions, and hypothermia. The clinical chemistry of CPS1 deficiency may be unremarkable except for the hyperammonemia, or there may be respiratory alkalosis. Amino acid analysis of the plasma at the time of hyperammonemia reveals elevation in glutamine and usually alanine, and sometimes aspartic acid.
