HLA-A3 (A3) is a

human leukocyte antigen The human leukocyte antigen (HLA) system or complex is a complex of genes on chromosome 6 in humans which encode cell-surface proteins responsible for the regulation of the immune system. The HLA system is also known as the human version of th ...

serotype A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the epi ...

'' within

HLA-A HLA-A is a group of human leukocyte antigens (HLA) that are encoded by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one of three major types of ...

serotype group. The serotype is determined by the antibody recognition of α³ subset of HLA-A α-chains. For A3, the alpha, "A", chain are encoded by the HLA-A allele group and the β-chain are encoded by B2M

locus Locus (plural loci) is Latin for "place". It may refer to: Entertainment * Locus (comics), a Marvel Comics mutant villainess, a member of the Mutant Liberation Front * ''Locus'' (magazine), science fiction and fantasy magazine ** ''Locus Award' ...

. This group currently is dominated by A*03:01. A3 and A are almost synonymous in meaning. A3 is more common in Europe, it is part of the longest known multigene

haplotype A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...

, A3~B7~DR15~DQ6.

Serotype

A3 is primarily composed of A*03:01 and *03:02 which serotype well with anti-A3 antibodies. There are 26 non-synonymous variants of A*03, 4 nulls, and 22 protein variants.

Associated diseases

A3 serotype is a secondary risk factor for ''

myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...

'' and lower CD8⁺ levels in

hemochromatosis Iron overload or hemochromatosis (also spelled ''haemochromatosis'' in British English) indicates increased total accumulation of iron in the body from any cause and resulting organ damage. The most important causes are hereditary haemochromatosi ...

patients. The HFE (Hemochromatosis) locus lies between A3 and B7 within the A3~DQ6 superhaplotype.

In HIV

HLA-A3 selects HIV evolution for a mutation Gag KK9 epitope and results in a rapid decline in the CD8 T-cell response. CD8 T-cells are responsible for quickly killing HIV infected CD4+ cells. This type of evolved response may not be specific for HLA-A3 and since HIV is capable of adapting quickly in situ to selective factors.

Alleles

Associated diseases

A*03:01 modulates increased risk for

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This d ...

A3~B haplotypes

A3-B7 is part of the A3~DQ2 superhaplotype A3-B8 (Romania, svanS)
A3~B35 (Bulgaria, Croatia, E. Black Sea)
A3~B55 (E. Black Sea)

A3~Cw7~B7

A3~B7 is bimodal in frequency in Europe with one node in Ireland and the other in Switzerland, relatively speaking Switzerland appears to be higher. A3~Cw7~B7 is one of the most common multigene haplotypes in the western world, particularly in Central and Eastern Europe. A ~ C ~ B ~ DRB1 ~ DQA1 ~ DQB1

References

{{HLA-A serotypes 3