Mini Review: HLA B27 and its Immunogenetics in Ankylosing Spondylitis

Mini Review: HLA B27 and its Immunogenetics in Ankylosing Spondylitis

Human Leucocyte Antigen (HLA) B27 is one of the antigens of class I major histocompatibility complex (MHC) that has strongly been associated with development of various spondyloarthropathies [1]. The gene for HLA B27 is located on short arm of chromosome 6, at 6p21.3 [2] (Figure 1), spanning an area of 4287 base pairs (bp). It contains 7 exons and 6 introns, in addition to a TATA, a poly A and four alternate splicing signals [3] (Figure 2).Exon 1 encodes leader peptide, exon 2 and 3 encode alpha 1 & alpha 2 domains, exon 4 encodes alpha 3, exon 5 encodes the transmembrane region, and exon 6 & 7 encode cytoplasmic tail. The product of this gene is 362 amino acid protein comprising three alpha chains associated with a beta2 microglobulin chain which is encoded by chromosome 15.