1) HLA-DR (also a gene of the MHC, along with HLA-B27) has been identified as a possible factor in predisposition to AS. However, more details are unavailable at this time due to the linkage of HLA-DR with HLA-B27, causing the results of the studies to be difficult to analyze.
2) Regions on chromosomes 2q, 6p, 6q, 10q, 11q, 16q, 17q, and 19q have also been implicated, but more specific details are not known.
3) The IL1-RA gene is an important gene that produces an anti-inflammatory chemical. It has been discovered in 2 studies that sibling pairs with AS all have this gene. More studies involving this gene and its affect on AS are currently being conducted.
4) The ank gene and its variants are also being analyzed. Since the ank gene involves keeping abnormal bone formation under control, it is thought that the ank gene may play a role in AS.
It has been hypothesized that bacteria may trigger AS, as well as some other forms of arthritis. However, this has not been proven, and research is still being conducted on this issue.
