HLA antigens in females with ankylosing spondylitis and other forms of seronegative rheumatic diseases.

A total of 222 female patients with seronegative rheumatic diseases were investigated by sacroiliac joint X-ray and HLA-A, B and Ctyped. The frequency of the B27 antigen was significantly increased in the following groups: definite pelvospondylitis (26 patients and relative risk (RR) = 99), possible pelvospondylitis (20 patients, RR=4.5), definite sacroiliitis (14 patients, RR-20.1) and uroarthritis (8 patients). When 24 B27 negative patients from these B27 associated diseases were analysed, significantly increased frequencies of the BW22 (RR=16.7) and CW1 (RR=14.4) antigens were found. There were no significantly deviating HLA frequencies in the following diagnostic groups: clinical sacroiliitis (20 patients), polyarthritis with clinically silent sacroiliitis (12 patients), polyarthritis without sacroiliitis (47 patients), arthralgia preceded by beta-streptococcal infection (17 patients), other arthralgia (33 patients), osteo-arthritis (13 patients) and other arthritis (12 patients).