Immunogenetics of rheumatoid arthritis in Israel

Abstract

In an attempt to study the variation of associations between HLA and rheumatoid disease a population of 44 Ashkenazi and 29 non-Ashkenazi patients with Rheumatoid Arthritis were tested for HLA-A B, C and DR antigens and compared with the relevant control groups. In contrast to the results obtained in Middle European or North American Caucasians, Rheumatoid Arthritis in Israel is not associated with B15 and Cw3, indicating that it is very unlikely that B- and C-locus antigens are involved in coding for disease susceptibility for RA. The allele DR4 which is found associated with RA in almost all populations tested so far was in the total patient group (47.9%) slightly but not significantly more frequent than in the control group (38.3%). This difference was entirely due to a non-significant increase din the frequency of DR4 in the Ashkenzai patients (54.5%) compared to controls (40%), while the frequency of DR4 in non-Ashkenazi patients and controls was virtually identical (38.0% vs. 36.7%). Another surprising finding was that the frequency of HLA-DR1, which has been reported to be increased in different populations of patients with RA was found to be completely normal in the present study on Israeli patients. The alleles of the Bf and the GLO system did not show any significant difference between patients and controls. The surprising results concerning the lack of association of RA in Israeli patients with DR4 and with DR1 lead to the speculation, that RA may be associated not with DR4 but with a marker of a closely linked locus which is very highly associated in Middle European Caucasians with DR4 but which is less strongly associated with DR4 in Israeli Jews. One of the obvious candiates for such closely linked genes is the DQ system with the allele DQw3 and its splits.