EPIDEMIOLOGY OF SPONDYLOARTHROPATHIES AMO NG THE INDIGENOUS POPULATION OF CHUKOT PENINSULA .2. DISTRIBUTION OF HLA-B27 AMONG PATIENTS WITH SPONDYLOARTHROPATHIES

To establish the incidence of HLA-B27 among the indigenous population of Chukot Peninsula, a one-stage cross-sectional study was made of all the natives of the two settlements of Eastern Chukot Peninsula (Siren iki and Novo-Chaplino). At the moment of examination altogether 640 na tives lived in both settlements. Of these, 464 persons (72.5 %) could be examined clinically: HLA typing could be performed in 439 persons ( 68.6 %). Among the 439 natives examined, antigen B27 was identified in 141 cases (32.1 %). Among Eskimos, the number of HLA-B27-positive ind ividuals amounted to 39.7 %, among Chukchi to 18.9 % (p = 0,0005). Hal fbreeds occupied an intermediate position between the two groups. The frequency of NLA-B27-positive cases was 29.7 % among them. 7 patients were diagnosed to have diseases belonging to the group of spondyloarth ropathies. 2 persons presented with ankylosing spondyloarthritis, with Reiter's syndrome, 2 with undifferentiated spondyloarthropathies and 1 with juvenile chronic arthritis. All the patients with ankylosing sp ondyloarthritis and Reiter's syndrome appeared HLA-B27-positive.