Abstract
Propionyl-CoA carboxylase deficiency is now thought to be the primary enzyme defect in the disease previously called “ketotic hyperglycinemia”. In a 10 month old girl with mental retardation and seizures, who never showed clinical attacks of ketoacidosis while eating a usual infant diet, we found hyperglyinuria, modest hyperglycinemia (2.4–2.9 mg%; normal 1.6 ± 0.3 mg%), and an impaired plasma clearance of glycine after an oral load. Studies of glycine catabolism by leukocytes in vitro were normal but a sever defect in propionate oxidation was present. In addition, propionyl-CoA carboxylase activity in extracts of cultured fibroblasts was less than 1% of normal. To investigate propionate metabolism in vivo, oral amino acid loads were given. Isoleucine, a propionyl-CoA precursor, led to vomiting, lethargy, ketonuria, hyperlactatemia, and hyperammonemia within 1 day. Valine, which is metabolized to methylmalonyl-CoA, the product of the deficient enzyme, caused hyperammonemia within 1 day. VAline, which is metabolized to methylmalonyl-CoA, the product of the deficient enzyme, caused hyperammonemia but no symptoms, no ketonuria, and no increase in lactate over a five day period. Plasma glycine remained between 3.1 and 5.1 mg% during the oral isoleucine and valine loads. Thus, propionyl-CoA carboxylase deficiency need not cause clinical attacks of ketoacidosis and must be considered in any infant with even slightly evelvated plasma and urine glycine concentrations.
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Mahonev, M., Hsia, Y. & Rosenberg, L. Propionyl-CoA carboxylase deficiency (propionicacidemia): A cause of non-ketotic hyperglycinemia. Pediatr Res 5, 395 (1971). https://doi.org/10.1203/00006450-197108000-00102
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DOI: https://doi.org/10.1203/00006450-197108000-00102
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