Familial reactive arthritis of Reiter's and ankylosing spondylitis types in the HLA-27 genotype.

The close relationship between Reiter's disease and ankylosing spondylitis, which had previously been suspected on the grounds of family and population studies, has been re-emphasised following the recent demonstration of their common close association with the HLA-27 genotype. Nevertheless there are few case reports of both conditions occurring simultaneously in first degree relatives; and documentation of HLA genotype in such families was not generally considered before 1973. Both varieties of reactive arthritis are reported here as occurring in first degree relatives sharing HLA-27 genotype.