SUMMARY

To assess the association between HLA-DRB1 and elderly-onset rheumatoid arthritis (RA) (EORA) in Japanese people, we analysed the HLA-DRB1 antigen frequencies of EORA patients. The age at onset distribution of 852 Japanese RA patients was analysed, and EORA was defined as an age at onset of 60 yr or older. Among the 852 RA patients, 120 (14.1%) were EORA patients. Their HLA-DRB1 antigen frequencies were assessed for significant deviation from those of the control (n = 652) and adult-onset RA (AORA; disease onset between 16 and 59 yr; n = 732) groups. The Japanese EORA patients were positively associated with DRB1*0101, *0405 and *1502, and the relative risks were 2.7, 1.9 and 2.2, respectively. The frequency of DRB1*1502 was also significantly higher among the EORA patients than in the AORA patients. The EORA patients showed dierent trends from the AORA patients in their frequency of HLA-DRB1 alleles, which suggests that EORA may be a dierent subset from AORA in light of its immunogenetic background. KEY WORDS: Elderly-onset rheumatoid arthritis, Age at disease onset, HLA-DRB1 alleles, HLA-DRB1*1502. RHEUMATOID arthritis (RA) has been generally thought to be a disease with onset in middle age. However, cases of RA beginning later in life [defined as after age 55 or 60 yr, and called elderly-onset RA (EORA)] are by no means infrequent [1, 2]