HLA-B and ankylosing spondylitis: The HLA-B*0801, HLA-B*38, HLA-B*3901, and HLA-C*0701 genes are associated with peripheral arthritis and spondylitis with asymmetric sacroiliitis, discontinuous spondylitis with non-marginal syndesmophytes (psoriatic spondylitis), while the HLA-B*27-5 gene is associated with symmetric sacroiliitis, gradually ascending spondylitis, and marginal syndesmophytes (typical of ankylosing spondylitis) and enthesitis [22,23,24].