ASSOCIATION OF DMA AND DMB WITH RA IN JAPANESE

Objective: The contribution of polymorphism of DMA and DMB alleles to the pathogenesis of Japanese RA was studied, The association of DM all eles with HLA-DRB10405 and *0802, which were positively and negativel y susceptible to Japanese RA, respectively, is also discussed. Methods : DMA and DMB typing was carried out in 91 Japanese RA patients and in 77 normal subjects by the PCR-RFLP (restriction fragment length polym orphism) method. HLA-DRB104 and *08 genotyping were carried out by th e PCR-SSCP (single-stranded DNA conformation polymorphism) method. Res ults: Allele frequencies of DMB0101 and DMB*0102 were slightly higher (52.2% and 27.0%) and the allele frequency of DMB0103 was slightly l ower (25.8%) in RA, but these differences were not significant. The in crease of DMB0102 was due to a negative association with HLA-DRB1*080 2 [p < 0.05, pc = not significant (NS)]. The decrease of DMB0103 was due to a positive association with DPB10802 (p < 0.005, pc < 0.05). T he increase of DMB0101 was possibly due to a weak association with HL A-DRB10405, (p = NS). Positivity of rheumatoid factor did not affect the prevalence of DMA and DMB alleles. Conclusion: Association analysi s among DMA, DMB and DRB1 (0405 and *0802) indicate that slight incre ases or decreases in DMB0101, DMB*0102 and DMB*0103 are not primary i ndicators but reflect an increase in HLA-DRB10405 and a decrease in H LA-DRB10802 in Japanese RA.