ASSOCIATION OF THE ACHR-ALPHA-SUBUNIT GENE (CHRNA), DQA1-ASTERISK-0101, AND THE DR3 HAPLOTYPE IN MYASTHENIA-GRAVIS - EVIDENCE FOR A 3-GENE DISEASE-MODEL IN A SUBGROUP OF PATIENTS

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular j unction having multigene control. HLA-linked loci and the HB14 micros atellite marker located within the CHRNA gene which encodes the muscul ar acetylcholine receptor (AChR) alpha-subunit, the target self-antige n, were previously associated with MG. Combined analysis of these loci revealed a significant increase of DQA10101 alleles in HB*14+ vs. HB 14- patients and of DQA1*0501 alleles in HB*14/DQA1*0101 patients. Im portantly, the effect of DQA10101 was independent of allelically asso ciated DQB1 and DRB1 genes. In contrast, the effect of DQA10501 could not be dissociated from that of DRB103 and DQB1*0201 on the extended DR3 haplotype. These results indicate that a combination of three gen es, of which two are linked to HLA, contributes to disease susceptibil ity in a subgroup of MG patients. (C) 1997 Academic Press Limited.