Causes of Ankylosing Spondylitis

HLA-B27

The cause of ankylosing spondylitis is not completely known. However, a particular gene has been identified that is closely linked to this condition. Research has shown that most people who have ankylosing spondylitis carry a gene known as human leukocyte antigen B27 (HLA-B27).Having HLA-B27 increase possibilty of having ankylosing spondylitis.
However, if you have the gene it does not necessarily mean that you will also have AS. Among people with ankylosing spondylitis 9 out of 10 suffer from HLA-B27.
It is estimated that 8 in 100 people in the general population have the HLA-B27 gene but do not suffer with AS.Testing for the this gene is not a very reliable method of diagnosing ankylosing spondylitis because some people can have the HLA-B27 gene but not have ankylosing spondylitis.

Family history

Ankylosing spondylitis can run in families, and the HLA-B27 gene can be inherited from family member.If you have a relative who is suffering with ankylosing spondylitis such as a parent,brother or sister, you are three times more likely to develop AS compared to someone who does not have a relative with AS.