Occurrence of HLA antigens in patients with ankylosing spondylitis and in their families.

The HLA typing (A and B loci) was performed in 55 individuals with ankylosing spondylitis (a.s.) in 74 relatives of their families and in 394 normals. HLA B-27 antigen was found in 80% of tested patients with a.s. The relative risk for B-27 being 30.1 and for A2 -- 1.65. In patients with a.s. lacking B-27 antigen the course of the disease did not differ from that in B-27 positive subjects. Uveitis has been revealed in 36.4% of B-27 patients and only in 9.9% of those negative for B-27. The results obtained in families display four different patterns as concerns genetics and morbidity: 1) in all 3 generations the presence of B-27 was accompanied by a.s., 2) in none of tested family members (diseases or healty) the B-27 antigen was confirmed, 3) there was correlation between B-27 and the disease symptoms, 4) the incidence of a.s. was associated with B-27 homozygotism. The results favour the idea that B-27 antigen is a disease determining factor, however, there is probably another allelic gene (nes) cooperating with B-27 locus. The B-27 homozygotism increases markedly the risk for a.s. The course of the diseases seems to be determined by environmental factors.