Mutation of the 97-197-197-1subunit of the pyruvate dehydrogenase complex,in relation to heterogeneity

Summary Pyruvate dehydrogenase complex was studied using bio- and immunochemical methods in cultured cells derived from two patients with the severe type and one patient with the mild type of pyruvate dehydrogenase complex deficiency. In patients 1 and 2, enzyme activity was all but undetectable and associated with the absence of E₁ subunit of the complex. Patient 3 had a slightly reduced level of enzyme activity, and this was associated with a larger form of E₁ subunit. The amount and size of E₁ mRNA in the three patients was similar to that of control samples. Thus, the severity of E₁ deficiency in these three patients is likely to depend on the type of mutation in the pyruvate dehydrogenase E₁ subunit and the synthesis and degradation rate of the subunit.