Abstract
Assays of liver from patients with RS reveal omithine transcarbamylaae (OTC) deficiency which nay be isolated, or nay occur in combination with carbamyl phosphate synthetase (CPS) deficiency. The correlation between these activities and clinical features of RS is unclear. Blockage of the urea cycle predominating at the OTC step would result in excessive formation of CA, whereas a co-existing block at the CPS step would tend to limit formation of OA from carbamyl phosphate. OA was determined directly in urine using high pressure liquid chromatograpny. Urine from consecutive 12-hr periods was assayed during acute and recovery phases of RS in a patient with isolated OTC deficiency (A), a patient with combined OTC and CPS deficiency (B), and in normal controls (C). A and B had normal renal functions. OA concentrations in C ware 5 to 10 μM. In A, OA was in excess of 2000 μM (312 mg/L) during the acute stage of illness. OA crystals formed in these specimens. OA in A decreased to normal levels during the 4-day recovery period. In B, CA concentrations during the acute phase were 2 to 3 times normal (23-30 μM), returning to normal within 5 days. These observations indicate that extreme elevations of OA may occur at the onset of RS with isolated OTC deficiency, whereas in RS with combined OTC and CPS deficiency OA elevation may be modest. These data suggest that OTC and CPS measured in vitro may correlate with OA formation during the active stage of RS.
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Thaler, M., Beidarman, B. UREA CYCLE ENZYMES AND OROTIC ACID (OA) IN REYE'S SYNDROME (RS). Pediatr Res 11, 522 (1977). https://doi.org/10.1203/00006450-197704000-00916
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DOI: https://doi.org/10.1203/00006450-197704000-00916