ABSTRACT
A small number of infants have been reported with a disorder in which severe lactic acidosis has been associated with excretion of large quantities of citric acid cycle intermediates and there is defective activity of the pyruvate dehydrogenase complex (PDHC) (Figures 51.1-51.3) and the other dehydrogenases involved in oxidative decarboxylations [1-8]. All but one [2] have died in infancy. In most, defective activity of lipoamide dehydrogenase (E3) was reported or presumed [4-7]. In one [8] the activity of E3 was normal, but improved catabolism of branched-chain amino acids after the growth of fibroblasts in medium supplemented with lipoic acid suggested a defect in an enzyme catalyzing the attachment of lipoic acid to a component of the enzyme complexes.
