Non-B27 MHC associations of ankylosing spondylitis.

Ankylosing spondylitis (AS) has been associated with human leukocyte antigen (HLA)-B27 for over 30 years; however, the mechanism of action has remained elusive. Although many studies have reported associations between AS and other genes in the major histocompatibility complex (MHC) in AS, no conclusive results have emerged. To investigate the contribution of non-B27 MHC genes to AS, a large cohort of AS families and controls were B27 typed and genotyped across the region. Interrogation of the data identified a region of 270 kb, lying from 31 952 649 to 32 221 738 base pairs from the p-telomere of chromosome 6 and containing 23 genes, which is likely to include genes involved with susceptibility to AS.