Mutations in the gene for the E1β subunit: a novel cause of pyruvate dehydrogenase deficiency

We describe two unrelated patients with pyruvate dehydrogenase (PDH) deficiency attributable to mutations in the gene encoding the E1β subunit of the complex. This is a previously unrecognised form of PDH deficiency, which most commonly results from mutations in the X-linked gene for the E1α subunit. Both patients had reduced immunoreactive E1β protein and both had missense mutations in the E1β gene. Activity of the PDH complex was restored in cultured fibroblasts from both patients by transfection and expression of the normal E1β coding sequence.