Chromosome localization and RFLP analysis of PDC-E2: the major autoantigen of primary biliary cirrhosis.

Patients with primary biliary cirrhosis are well known for the presence of titer antibodies against dihydrolipoamide acetyltransferase, the E2 subunit of the pyruvate dehydrogenase complex. We have taken advantage of a cDNA probe for dihydrolipoamide acetyltransferase to explore the possibility of polymorphism of the E2 subunit by probing genomic DNA from 38 patients with primary biliary cirrhosis and 26 healthy controls. To detect restriction fragment length polymorphism, DNA was digested with ten specific restriction enzymes that often detect polymorphism, including Bam HI, Bgl II, Eco RI, Hind III, Hinf I, Msp I, Pst I, Pvu II, Rsa I and Taq I. A Taq I polymorphism was found in 19 of 38 patients with PBC and 6 of 26 normal controls. In addition, using fluorescence in situ hybridization, the gene for dihydrolipoamide acetyltransferase was mapped on human chromosome 11 band q23.1. Interestingly, this region of the long arm of chromosome 11 is often associated with cytogenetic abnormalities, including translocations.