Introduction: Human leukocyte antigens (HLA), because of associations between some HLA alleles and various disorders, are important in assessment of susceptibility to diseases. There are many studies showing that the most solid of such associations is between HLA-B27 and spondyloarthropathies particularly ankylosing spondylitis. The purpose of this study was to assess the association between HLA-B27 and ankylosing spondylitis in Iran, and finding the relative and absolute risk of ankylosing spondylitis with respect t HLA-B27 as well.

  Methods: Based on the studies done by others and recently by our group, the most valid technique in determining of HLA-B27 is polymerase chain reaction (PCR). The population under the study included 36 patients with ankylosing spondylitis and 30 of healthy volunteers. Allele specific PCR (using of complementary primers for specific sequences in exon-3 of HLA-B27 gene) used in PCR method. Estimations of relative and absolute risks of ankylosing spondylitis in presence of HLA-B27 antigen and also standard error of ratio for generalizing the result of present study to society were calculated.

  Results: Finally, it was revealed that based on PCR method, 69.4% of patients under the study were HLA-B27 positive and relative risk of affecting by ankylosing spondylitis in HLA-B27 positives was 65 times morethan others.

  Conclusion: There are some differences among the results of such studies done in different races around the world. These differences may be due to many factors including variable geographical distribution of microbes or HLA-B27 subtypes.

  Keywords: Ankylosing spondylitis, HLA-B27, PCR.

  Hakim 2005 8(1) 29-34.