Ornithine carbamoyltransferase deficiency

Ornithine carbamoyltransferase deficiency p Glnf, Citf, Alaj, Lysj, ArgJ,... 

Kay JD, Hilton-Jones D, Hyman N. Valproate toxicity and ornithine carbamoyltransferase deficiency. Lancet 1986 2(8518) 1283 1. 

Becroft. Pyrimidine and purine metabolites in ornithine carbamoyltransferase deficiency. J.Inher.Metab.Dis. 4 27 (1981). 

Fairbanks LD, Sebesta I, Simmonds HA, Leonard JV. The allopurinol loading test for evaluation of carriers for ornithine carbamoyltransferase deficiency. Clin Chim Acta 1994 224 45-54... 

As a congenital disorder, an enzyme deficiency in the urea cycle relates to carbamoylphosphate synthetase or N-ace-tyl-glutamate synthetase (= hyperammonaemia type I) and ornithine carbamoyltransferase (= hyperammonaemia type II) (D.B. Flannery et al., 1982). (27) (s. p. 594) This condition mainly affects the channelling of ammonium into the mitochondria and the conversion of ornithine into citrulline. (s. fig. 3.12) Similar acquired enzymopathies can be expected in Reye s syndrome and in cases of zinc deficiency. Such a hyperammonaemia syndrome can also produce the clinical picture of HE. 

Xp21.1 68.97 OTC Ornithine carbamoyltransferase 300461 Ornithine transcarbamylase deficiency, Duchenne muscular dystrophy... 

Elevated concentrations of orotic acid and uracil may be found in the urine of heterozygote carriers for urea cycle disorders, most commonly ornithine carbamoyltransferase (OCT) deficiency. This is due to the increased flux through the pyrimidine pathway which occurs, especially where the relevant enzymes are expressed only in liver tissue, as is the case when urea cycle enzymes are defective. A protein load was used previously to stress this route and the elevation in orotic acid excretion used as a diagnostic marker. However, the test frequently failed to detect known carriers. The al-lopurinol loading test (measurement of the increment in urinary orotic acid and orotidine in three separate 8 hour urine collections over the 24 hours following a 300 mg allopurinol tablet) is the most reliable test so far for carrier detection for such disorders [17]. 

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