Arginine 302 mutations in the pyruvate dehydrogenase E1alpha subunit gene: identification of further patients and in vitro demonstration of pathogenicity.

[pyruvate dehydrogenase deficiency]

Three further patients with mutations in the codon for arginine 302 of the E 1 alpha subunit of the pyruvate dehydrogenase complex have been identified . Mutations in this codon have now been found in nine patients with pyruvate dehydrogenase deficiency in seven unrelated families , in sharp contrast to the great majority of other PDH E 1 alpha mutations which have been described in single individuals only . Because of the relatively high frequency of this mutation and because very few PDH E 1 alpha mutations have been demonstrated to be causative , we have established a system for analysing the consequences of defined mutations using transfection of normal and mutant PDH E 1 alpha cDNA into transformed human fibroblasts which have no endogenous E 1 alpha mRNA or protein . Using this test system , we have demonstrated that the R 302 C mutation results in the production of PDH E 1 alpha protein which is devoid of enzymic activity .