Family studies in Bechterew's syndrome (ankylosing spondylitis). I. Prevalences of symptoms and signs in relatives of HLAB27 positive probands.

All available adult first-degree relatives of 66 patients with HLAB27 positive ankylosing spondylitis were examined clinically and radiographically and their white blood cells were HLA typed. Ten per cent of all relatives and 20% of HLAB27 positive relatives had Bechterew's syndrome. An additional 10% had minimal radiographical changes in the sacro-iliac joints, or peripheral arthropathy. Sixteen out of 19 persons who had minimal radiographical changes in the sacro-iliac joints were HLAB27 positive. Backache was common (25% or more) in any group of relatives, and did not discriminate well between relatives with or without Bechterew's syndrome. Spine or chest stiffness should prompt examination for Bechterew's syndrome, but is an inadequate diagnostic criterion for the syndrome. Typing for HLAB27 is probably the best prognostic test, although most HLAB27 positive persons did not exhibit any objective sign of disease. Repeated radiographical examination of HLAB27 negative persons should be avoided.