Lactic acidosis in three sibs due to defects in both pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes.

A Canadian Indian family is described in which three of the children were mentally retarded, and had seizures and other neurological abnormalities. They had chronic metabolic acidosis associated with elevated blood levels of lactate, pyruvate, and alanine. Two of the children excreted large amounts of pyruvic and alpha-ketoglutaric acids in the urine and had elevated plasma levels of glutamic acid and proline. Hypoglycemia occurred with fasting in two of the children. Treatment with pharmacological doses of thiamine, lipoic acid, biotin, riboflavin, and various dietary regimes was without effect. One child died at 3 1/2 months and another at 4 1/2 months; the third is still alive at 23 months of age. Enzyme assays revealed a low level of activity of both the pyruvate and alpha-ketoglutarate dehydrogenase complexes in cultured fibroblasts of one of the sibs. These patients appeared to have partial defects in the oxidation of pyruvate, as well as of alpha-ketoglutarate within the tricarboxylic acid cycle.