HLA DRB1, DMA, and DMB gene polymorphisms in rheumatoid arthritis

OBJECTIVE: To study the influence of DMA and DMB genes on susceptibility to Rheumatoid Arthritis (RA). METHODS: HLA-DRB1, DMA and DMB polymorphisms we re defined by PCR SSOP in 203 European Mediterranean RA patients and 181 un related healthy controls. RESULTS: No significant difference in the phenoty pe frequencies of DMA and DMB alleles was observed between patients and con trols. We found decreased frequencies of DMA*0102 and DMB*0104 in patients but this did not reach significance. These decreased frequencies could be d ue to a positive linkage disequilibrium with DRB1*0701, an allele which is underrepresented in RA patients. In stratified analysis with RA susceptibil ity Epitope positive (SE) DRB1 alleles, there was no significant difference in DMA and DMB phenotype frequencies between SE/SE, SE/X, and X/X patients versus controls. Among SE/X subjects, no significant difference in DM dist ribution frequencies was observed in DRB1*0101/X, 0102/X, 0401/X, 0404/X an d 0405/X groups. CONCLUSION: DMA and DMB poly morphism does not seem to inf luence susceptibility to develop RA. Differences in DMA phenotype frequenci es between patients and controls are secondary to linkage disequilibrium wi th DRB1 alleles. Human Immunology 60, 245-249 (1999). (C) American Society for Histocompatibility and Immunogenetics, 1999. Published by Elsevier Scie nce Inc.