Pyruvate dehydrogenase complex deficiency: biochemical and immunoblot analysis of cultured skin fibroblasts.

Cultured skin fibroblasts were obtained from 11 children with lactic acidemia and neurological disturbances. The residual activities of pyruvate dehydrogenase complex were 9 to 45% of control values in all specimens. Immunoblot analysis of mitochondrial proteins using polyclonal antibodies against the alpha and beta subunits of the first component (E1) of the pyruvate dehydrogenase complex revealed markedly decreased amounts of cross-reacting material in 4 boys who died in infancy. Two of the boys were half brothers related through a common mother. A fifth boy had an alteration of the electrophoretic mobility of the E1 alpha subunit and normal E1 beta subunit abundance. The remaining 6 patients (2 boys and 4 girls) had normal findings on Western blot assay, and all 11 patients had normal E2 and E3 patterns. These findings suggest that the E1 alpha subunit gene represents a genetically vulnerable site on the X chromosome. Decreased abundance of E1 components appears to be associated with death in infancy. A normal Western blot analysis is compatible with long-term survival despite decreased catalytic activity of the pyruvate dehydrogenase complex.