HLA-A3


HLA-A3 is a human leukocyte antigen serotype within HLA-A 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. This group currently is dominated by A*0301. 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*0301 and *0302 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 patients. The HFE 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*0301 modulates increased risk for multiple sclerosis

A3-B haplotypes

A3-B7 is part of the A3::DQ2 superhaplotype
A3-B8
A3-B35
A3-B55

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