HLA B27 in the population of northern Sweden.

The frequency of HLA B27 in blood donors born in northern Sweden was found to be 16.6%. This was significantly higher than in southern Sweden or in caucasians generally, with the exception of Finland. A close genetic relationship has been found between the population of northern Sweden and the Finnish. The higher frequency of HLA B27 is particularly interesting in view of the finding of a higher incidence of rheumatic diseases in northern than in southern Sweden. We also found a surprisingly large number of patients with reactive arthritides and ankylosing spondylitis in the patient registers of the rheumatology department, which further indicated a genetic influence on rheumatic disorders in northern Sweden.