HLA-B27

B*2705-β2MG with bound peptide 2bst
major histocompatibility complex (human), class I, B27
Alleles	B*2701, 2702, 2703, . . .
Structure (See HLA-B)		Available 3D structures
EBI-HLA	B*2701
	B*2702
	B*2703
	B*2704
	B*2705	2bsr, 2bss, 2bst, 2a83, 1w0v, 1uxs, 1ogt, 1hsa, 1jgd, 1jge
	B*2706
	B*2709	1w0w, 1uxw, 1of2, 1k5n

Human Leukocyte Antigen B*27 (subtypes B*2701-2724) is a class I surface antigen encoded by the B locus in the major histocompatibility complex (MHC) on chromosome 6 and presents microbial antigens to T-cells. HLA-B27 is strongly associated with a certain set of autoimmune diseases referred to as the "seronegative spondyloarthropathies". In the general population, about 8% Caucasian, 4% African, 2-9% Chinese, and 0.1-0.5% Japanese have the HLA-B27 antigen. In Northern Scandinavia (Lapland), 24% of people are HLA-B27 positive while 1.8% have associated ankylosing spondylitis (AS).

Serotype

Disease associations

Spondylarthropathies

The relationship between HLA-B27 and many diseases has not yet been fully elucidated. Though it is associated with a wide range of pathology, it does not appear to be the sole mediator in development of disease.^{[citation needed]} For example, while 90% of people with ankylosing spondylitis (AS) are HLA-B27 positive, only a fraction of people with HLA-B27 ever develop AS. This raises two important questions: why don't all HLA-B27 positive people develop AS, and why do some people who are HLA-B27 negative develop it?^{[citation needed]} The literature is inconclusive, though several theories have been suggested. Research however has been discontinued in many countries due to lack of funding.^{[citation needed]}

Juvenile Spondylarthropathies

In Croatian children, two B27 alleles were found associated with disease, B*2702, B*2705.^[3] The study showed also B*0702 in coorperation with B*27, the HLA-B*07/B*27 combination with D6S273-134 genomic marker allele and was found not to be the result of linkage disequilibrium. B*2795 was found to be dominant allele associated.

Associated pathology

In addition to its connection with ankylosing spondylitis, HLA-B27 is implicated in reactive arthritis, certain eye disorders such as acute anterior uveitis and iritis, psoriatic arthritis and ulcerative colitis. The common association with HLA-B27 leads to increased association of these disorders with each other.^[4]

See also

• Human leukocyte antigen

External links

• HLA-B27 Syndromes at eMedicine by A. Luisa Di Lorenzo, MBBCh
• Bowness P (2002). "HLA B27 in health and disease: a double-edged sword?". Rheumatology (Oxford) 41 (8): 857–68. doi:10.1093/rheumatology/41.8.857. PMID 12154202. 
• Online 'Mendelian Inheritance in Man' (OMIM) 142830
• MeSH HLA-B27

References

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