Human Leukocyte Antigen (HLA) B27 (subtypes B*2701-2759) is a class I surface antigen encoded by the B locus in the major histocompatibility complex (MHC) on chromosome 6 and presents antigenic peptides (derived from self and non-self antigens) to T cells. HLA-B27 is strongly associated with ankylosing spondylitis (AS), and other associated inflammatory diseases referred to collectively as "spondyloarthritis".
Various methods have been developed for the identification of the HLA-B27 allele. The PCR-based HLA-typing methods, including the standard PCR with sequence-specific primers (SSP), have become widely used alternatives to serologic methods in clinical practice; however, these techniques are time-consuming and laborious. The drawbacks of the current methods, such as long processing time and the requirement for post-PCR manual procedures, have been overcome by the introduction of real-time PCR.