Spondyloarthropathies in circumpolar populations of Chukotka (Eskimos and Chukchi): epidemiology and clinical characteristics.

OBJECTIVE: We sought to determine the prevalence of HLA-B27 and the prevalence and nature of spondyloarthropathies in the native residents of Eastern Chukotka, Siberia, Russia. METHODS: We conducted a cross sectional study with medical examination and interview of 464 of 640 (72.5%) native residents of 2 Eastern Chukotka settlements, Sireniki and Novo-Chaplino. RESULTS: Among them were 212 Eskimos, 98 Chukchi and 154 subjects of mixed race. There were 2 subjects (0.4%) with ankylosing spondylitis, 2 with Reiter's syndrome, 2 with undifferentiated spondyloarthropathy and 1 with late onset pauciarticular juvenile arthritis consistent with spondyloarthropathy. Four of the subjects were Eskimos, 2 were of mixed race, and 1 was Chukchi. We found a high percentage of HLA-B27 antigen in the population, 32% in the native population overall, and 40% among the Eskimos. CONCLUSION: Our data complement other studies of circumpolar populations and reinforce the reported high prevalence of spondyloarthropathy and HLA-B27 among those people.

[The epidemiology of spondyloarthropathies among the native inhabitants of Chukotka. 2. The prevalence of HLA-B27 in the population and among spondyloarthropathy patients]. / Epidemiologiia spondiloartropatii sredi korennykh zhitelei Chukotki. Soobshchenie 2. Raspredelenie HLA-B27 v populiatsii i sredi bol'nykh spondiloartropatiiami.

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 (Sireniki and Novo-Chaplino). At the moment of examination altogether 640 natives 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 individuals amounted to 39.7%, among Chukchi to 18.9% (p = 0.0005). Half-breeds 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 spondyloarthropathies. 2 persons presented with ankylosing spondyloarthritis, 2 with Reiter's syndrome, 2 with undifferentiated spondyloarthropathies and 1 with juvenile chronic arthritis. All the patients with ankylosing spondyloarthritis and Reiter's syndrome appeared HLA-B27-positive.