Which chromosome is HLA B27 on


1 definition

HLA-B27 is a genetically determined antigen variant of the human leukocyte antigen-B (HLA-B). It belongs to the MHC class I complex, which is located on the surface of almost all cells and is used for antigen presentation.

2 background

In the presence of HLA-B27 (HLA-B27 positive) is the probability of occurrence of certain diseases compared to people without HLA-B27 type (HLA-B27 negative) elevated.

About 8% of the Western European population carry the HLA-B27 trait. It can be used for differential diagnosis in the search for HLA-associated diseases and is then determined in the laboratory using HLA typing.

In Germany, the Genetic Diagnostics Act must be observed when examining genetic characteristics that are relevant to a disease.

3 genetics

The HLA-B gene is located on chromosome 6 at gene locus 6p21.33. It consists of a group of around 130 very similar alleles that encode 105 subtypes of HLA-B27. The latter are systematically numbered and labeled HLA-B * 2701 to HLA-B * 27106.[1]

4 pathomechanism

The molecular mechanisms by which HLA-B27 favors the development of certain diseases are currently (2019) still unclear. Immunological cross-reactions with bacterial antigens or a binding of certain antigens to HLA-B27 are discussed as possible causes. Other authors assume that there is an incorrect folding of the tertiary structure of HLA-B27, which triggers a stress reaction in the cell, the so-called Unfolded Protein Response (UPR).

5 Associated Diseases

Diseases associated with HLA-B27 can be noted by the abbreviation “PAIR”, where P stands for psoriasis, A for ankylosing spondylitis, I for “inflammatory bowel disease” and R for reactive arthritis. These include the following diseases:

6 sources

  1. ^ Khan MA. Polymorphism of HLA-B27: 105 subtypes currently known. Curr Rheumatol Rep. 2013; 15: 1-6. doi: 10.1007 / s11926-013-0362-y.

7 literature

  • Laborlexikon.de; accessed on March 19, 2021