Lacticacidaemia due to pyruvate dehydrogenase deficiency, with evidence of protein polymorphism in the alpha-subunit of the enzyme.

In three infants with neonatal lacticacidaemia, a deficiency in the E1 (pyruvate dehydrogenase) component of the pyruvate dehydrogenase complex was demonstrated in skin fibroblast cultures. Residual activities of the pyruvate dehydrogenase complex in the activated state were 1.6%, 3.9% and 18.8% of control values, respectively. Immunoprecipitation of extracts of cultures skin fibroblasts grown on 35S-methionine with anti-pyruvate dehydrogenase complex antibody revealed an abnormality in the E1 alpha-component of these three patients when visualised after sodium dodecyl sulphate/polyacrylamide gel electrophoresis. This component appeared to have a slightly lower molecular weight than did this protein from control cell strains. Cell strains from other patients with a deficiency of the pyruvate dehydrogenase complex did not exhibit this defect. Three patients also showed dysmorphism and developmental abnormalities of the central nervous system.