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'' 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 α
3 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, 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''
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 haemochromatos ...
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
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