Hi, Hilary,

There are several people whom test negative for HLA-B27, and yet still have AS. Not very reassuring - on the testing outcome - huh, considering people have still been dx'd with it.

For numbers, you might want to check out these pages:


http://www.spondylitis.org/about/as.aspx

"....This marker is found in over 95% of people in the causcasion popluation with AS (the association between ankylosing spondylitis and HLA-B27 varies greatly between ethnic and racial groups, see our AS Diagnosis section for more information). It is important to note, however, that you do not have to be HLA-B27 positive to have AS. Also, a majority of the people with this marker never contract ankylosing spondylitis...."


http://www.spondylitis.org/about/as_diag.aspx

"....the HLA-B27 test is not a diagnostic test for AS. Also, the association between AS and HLA-B27 varies in different ethnic and racial groups. It can be a very strong indicator in that over 95% of people in the caucasion population who have AS test HLA-B27 positive. However, only 50% of African American patients with AS possess HLA-B27, and it is close to 80% among AS patients from Mediterranean countries...."