Distribution of HLA B27 and ankylosing spondylitis in the Hungarian population.

On the basis of (a) our epidemiological studies of ankylosing spondylitis (AS) (males 0.4 per cent, females 0.08 per cent), (b) typing of 352 normal persons (frequency of HLA B27 = 12.78 per cent), and (c) typing of 55 AS patients (frequency of HLA B27 = 92.73 per cent), we have calculated the prevalence of AS for the total Hungarian population over 15 years of age. Among males with the B27 anitgen, AS occurs in 2.9 per cent, and in B27 positive females 0.58 per cent. In the population without the B27 antigen, the prevalence of the disease is 0.03 per cent and 0.006 per cent respectively. The quotients of these data show that a person with the B27 antigen has approximately 87 times greater risk of developing AS, than does a person of the same sex without this antigen.