Coit et al. [131] identified a total of 68 differentially methylated sites in a study of ankylosing spondylitis (AS) patients and osteoarthritis controls; HCP5 and POU5F1 were both hypomethylated in HLA-B*27-positive compared to HLA-B*27-negative AS patients. Here, HLA-B is linked to ankylosing spondylitis.