HLA-A is a group of human leukocyte antigens (HLA) that are coded for by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is simply the major histocompatibility complex (MHC) specific to humans. HLA-A is one of three major types of human MHC class I cell surface receptors. The others are HLA-B and HLA-C. The receptor is a heterodimer, and is composed of a heavy α chain and smaller β chain. The α chain is encoded by a variant HLA-A gene, and the β chain (β₂-microglobulin) is an invariant β₂ microglobulin molecule. The β₂ microglobulin protein is coded for by a separate region of the human genome.

MHC Class I molecules such as HLA-A are part of a process that presents short polypeptides to the immune system. These polypeptides are typically 7-11 amino acids in length and originate from proteins being expressed by the cell. There are two classes of polypeptide that can be presented by an HLA protein: those that are supposed to be expressed by the cell (self) and those of foreign derivation (non-self). Under normal conditions cytotoxic T cells, which normally patrol the body in the blood, "read" the peptide presented by the complex. T cells, if functioning properly, only bind to non-self peptides. If binding occurs, a series of events is initiated culminating in cell death via apoptosis. In this manner, the human body eliminates any cells infected by a virus or expressing proteins they shouldn't be (e.g. cancerous cells).

HLA-A29 (A29) is a human leukocyte antigen serotype within HLA-A serotype group. The serotype is determined by the antibody recognition of α²⁹ subset of HLA-A α-chains. For A29, the alpha "A" chain are encoded by the HLA-A*29 allele group and the β-chain are encoded by B2M locus. This group currently is dominated by A*2902. A29 and A*29 are almost synonymous in meaning. A29 is a split antigen of the broad antigen serotype A19. A29 is a sister serotype of A30, A31, A32, A33, and A74.

A29 is more common in Western Africa and Southwestern Europe.

Serotype

Allele distribution

Haplotypes

For A29-Cw*16-B44 (A*2902:Cw*1601:B*4403) haplotype see Cw*16

References

HLA-A36 (A36) is a human leukocyte antigen serotype within HLA-A serotype group. The serotype is determined by the antibody recognition of α³⁶ subset of HLA-A α-chains. For A36, the alpha "A" chain are encoded by the HLA-A*36 allele group and the β-chain are encoded by B2M locus. This group currently is dominated by A*3601. A36 and A*36 are almost synonymous in meaning.

A36 is more common in Africa (North and East) and Central Asia. A36 is rare HLA-A allele group.

Serotype

A36 has a high false serotyping rate to A1.

Distribution

A36 is largely limited to Africa. Outside Africa more than half of the populations have no A36 and the majority that do, have only trace levels. The exception is in Central/East Central Asia. This appears not to be coincidental. HLA DR3-DQ2 linkage and frequency indicates a strong possibility of a recent migration from either North or West Africa in which the DR3-DQ2 (notably DRB1*0302) and A*33-B*58 haplotypes were carried into and redistributed from Central Asia into the surrounding populations.