Abstract
A lethal carbamylphosphate synthetase (CPS: EC 6.3.4.16) deficiency (McKusick 23730) was found in a newborn girl; who presented on the second day of life with acute hyperammonaemia, hypotonia, seizures and who died in a coma 6 days after birth. The activity of the mitochondrial urea cycle enzymes, CPS and ornithine transcarbamylase (OTC: EC 2.1.3.3) were measured on a needle biopsy sample taken from liver and showed that CPS was 1.4% of the normal mean (0.09 nmol/min/mg protein) whereas OTC activity was normal (110 nmol/min/mg protein). Immunological analysis of the liver sample showed no detectable immunoreactive CPS and confirmed the presence of normal levels of OTC. RNA was extracted from postmortem liver andin vitro translation experiments showed that there was no translatable CPSmRNA and confirmed that no CPS protein was synthesized in this child. The absence of translatablemRNA is explicable in terms of a genetic defect which results in a failure to synthesizemRNA for CPS, or synthesis of a defective form ofmRNA which is not translated.
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Graf, L., McIntyre, P., Hoogenraad, N. et al. A carbamylphosphate synthetase deficiency with no detectable immunoreactive enzyme and no translatablemRNA. J Inherit Metab Dis 7, 104–106 (1984). https://doi.org/10.1007/BF01801764
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DOI: https://doi.org/10.1007/BF01801764