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A carbamylphosphate synthetase deficiency with no detectable immunoreactive enzyme and no translatable m RNA
Author(s) -
Graf L.,
McIntyre P.,
Hoogenraad N.,
Brown G.,
Haan E. A.
Publication year - 1984
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01801764
Subject(s) - ornithine transcarbamylase , rna , urea cycle , enzyme , citrullinemia , liver biopsy , hypotonia , biology , microbiology and biotechnology , messenger rna , in vitro , urea , biochemistry , medicine , endocrinology , biopsy , gene , amino acid , arginine
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 and in vitro translation experiments showed that there was no translatable CPS m RNA and confirmed that no CPS protein was synthesized in this child. The absence of translatable m RNA is explicable in terms of a genetic defect which results in a failure to synthesize m RNA for CPS, or synthesis of a defective form of m RNA which is not translated.