CLASS-I HLA ANTIGENS IN SPONDYLOARTHROPATHY - OBSERVATIONS IN ALASKANESKIMO PATIENTS AND CONTROLS

Objective. To assess the role of HLA-B27 and other class I histocompat ibility antigens in overall risk and clinical manifestations of spondy loarthropathy (SpA) in Alaskan Eskimos, Methods. Class I antigens were studied in 104 patients with SpA and in 111 controls. The frequencies of HLA-A, B, and Cw antigens were determined in patients with SpA wit h various clinical manifestations and compared to frequencies observed in controls. Results. Only HLA-B27 differed significantly in cases an d controls. Except for B27, no association of particular antigens with specific syndromes or disease features was found. Patients with B27 h ad more extraarticular manifestations than patients who lacked B27 ant igen, Patients putatively homozygous for B27 did not appear to have mo re severe disease than those who were heterozygotic. B27 was most clos ely associated with ankylosing spondylitis [odds ratio (OR)=210], less so with reactive arthritis (OR=12.9) and undifferentiated SpA (OR=4.6 ), Conclusion. Observations in other population groups that implicated B27 cross reactive group (CREG) and other A, B, and Cw antigens as ri sk factors for developing SpA were not confirmed in Alaskan Eskimos. N or were CREG or other B antigens either alone or in combination with B 27 associated with specific clinical syndromes. Only HLA-B27 was stron gly associated with disease and with extraarticular manifestations.