Family studies with HLA typing in Reiter's syndrome.

Twelve consecutive patients with Reiter's syndrome, nine with the B27 antigen (B27 positive) and three without (B27 negative), and their 45 first degree relatives were studied clinically and with HLA typing. Two of the four adult male first degree relatives with the B27 antigen had classic Reiter's syndrome. In addition, one of two B27 positive adult male second degree relatives studied in one family had classic Reiter's syndrome. The data, although limited, suggest that the familial occurrence of Reiter's syndrome is higher than previously recognized, especially in adult male first degree relatives with the B27 antigen, and is similar to the degree of familial aggregation reported in ankylosing spondylitis.