To determine whether the HLA-DMA and DMB genes, whose encoded molecules are involved in HLA class II-restricted antigen presentation, contribute to the genetic susceptibility to rheumatoid arthritis (RA).
One hundred ninety-one RA patients, 147 control subjects, and 218 HLA-DRB1 genotype-matched control subjects were oligotyped for DMA and DMB genes.
DMA*0103 and DMB*0104 were significantly increased in the RA patients compared with the randomly selected and the matched controls, thus indicating a direct influence of the DM genes. After stratification of the patients and matched controls according to DRB1 genotypes, only DMA*0103 was increased in the RA patients with DRB1*01, as well as in the patients negative for the RA-susceptibility DR alleles.
Our results suggest that DMA*0103 could play an additional role in the genetic susceptibility to RA.