Genetic studies in ankylosing spondylitis.

It is likely that ankylosing spondylitis is genetically heterogeneous. The evidence favours the gene for HLA-B27 being the major genetic factor responsible for susceptibility. The finding of a greater prevalence of disease in B27 positive first-degree male relatives of probands than in random B27 positive controls, suggests the existence of other genes for susceptibility, possibly HLA-linked.