THE HOMOZYGOTE OF HLA-DRB1-ASTERISK-0901, NOT ITS HETEROZYGOTE, IS ASSOCIATED WITH RHEUMATOID-ARTHRITIS IN JAPANESE

To assess the association between HLA-DRB10901 and Japanese rheumatoi d arthritis (RA) patients, we analyzed the frequency of HLA-DRB10901 in 852 Japanese RA patients. We found that the homozygote of DRB10901 was associated with Japanese RA patients, while the heterozygote of D RB10901 was not. These findings suggest that DRB1*0901 is a weakly su sceptible allele of RA, which in our investigation was not associated with RA by a single allele, but can be by a homozygote. DRB10901 does not have the shared epitope, and it is suggested that there may be so me mechanism of the association between HLA-DRB1 and RA other than the shared epitope, which was not strong.