Symptoms and signs among relatives of patients with HLA B27 ankylosing spondylitis: Correlation between back pain, spinal movement, sacroilitis, and HLA antigens.

In order to determine the prevalence of ankylosing spondylitis and the prevalence and pattern of back pain amongst the relatives of patients with ankylosing spondylitis, 63 first degree relatives of 14 propositi were assessed by means of questionnaire, physical examination, and radiology. There were no significant differences in the responses of the B27 positive and negative relatives in relation to prevalence, severity and character of back pain. Ankylosing spondylitis was found in 6.5 per cent of B27 positive relatives and 3.1 per cent of B27 negative relatives; sacroilitis being present in 12.9 per cent of B27 positive relatives and 6.3 per cent of B27 negative relatives. A family studied is presented as a possible corssover between HLA B locus and disease "predisposition" genes. It is suggested patterns of back pain may not be as discriminating as has been thought.