Ankylosing spondylitis (AS) is a common, highly heritable inflammatory arthritis affecting primarily the spine and pelvis and affects approximatively 0.5% of the population. Accumulating evidence has demonstrated that human leukocyte antigen (HLA) class I molecule B27 (HLA-B27) is strongly associated to AS : > 90 % of AS patients are HLA-B27 positive. Over 100 different allelic variants of B27 have been recognized (HLA-B2701 to HLA-B27106) in AS patients, among which B27*05 and B27*02 are widely prevalent in European populations, and B27*04 is predominant in Asian populations. The LAMP human HLA-B27 direct detection kit detects most HLA-B27 alleles, included European most AS associated subtypes B*2702 and B*2705, Asian subtype B*2704 and African subtype B*2703. It is important to note that the HLA-B27 test is not a diagnostic test for ankylosing spondylitis. Moreover, the association between AS and HLA-B27 varies among different ethnic and racial groups. Nevertheless, it can be a very strong indicator in that more than 95 % of people in the Caucasian population who have AS test positive for HLA-B27. However, close to 80 % of AS patients from Mediterranean countries and only 50 % of African American patients with AS are HLA-B27 positive.