HLA-B [SEP] chromosome
are categorized together; for example, at least 28 very similar alleles are subtypes of HLA-B27. These subtypes are designated as HLA-B*2701 to HLA-B*2728.
The HLA-B gene is located on the short (p) arm of chromosome 6 at cytoband 21.3, from base pair 31,353,871 to 31,357,211 
Related conditions.
Ankylosing spondylitis: A version of the HLA-B gene called HLA-B27 increases the risk of developing ankylosing spondylitis. It is uncertain how HLA-B27 causes this increased risk
, while HLA-A11 is associated with the disease in Koreans. Several genes within this region of class I HLA are believed to be responsible for DPB, by allowing increased susceptibility to the disease. The common genetic background and similarities in the HLA profile of affected Japanese and Korean individuals were considered in the search for a DPB gene. It was suggested that a mutation of a suspected disease-susceptibility gene located somewhere between HLA-B and HLA-A had occurred on an ancestral chromosome carrying both HLA-B54 and HLA