HLA-A24
# HLA-A24

HLA-A24 (A24) is a human leukocyte antigen serotype within HLA-A serotype group. The serotype is determined by the antibody recognition of $α^{24}$ subset of HLA-A α-chains. For A24, the alpha, "A", chain are encoded by the HLA-A*24 allele group and the β-chain are encoded by B2M locus. This group currently is dominated by A*2402. A24 and A*24 are almost synonymous in meaning. A24 is a split antigen of the broad antigen HLA-A9 and it is a sister serotype of HLA-A23.

A*2402 has one of the highest "A" frequencies identified for a number of peoples, including Papua New Guineans, Indigenous Taiwanese (Eastern Tribals), Yupik and Greenland [Aleuts]. It is common over much of Southeastern Asia. In Eurasia it is least common in Ireland, and A24 is relatively uncommon in Africa except North Africa and Kenya.

## Serotype

A24 recognition of some HLA A*24 gene products :

| A*24 | A24 | A9 | Sample |
| - | - | - | - |
| allele | % | % | size (N) |
| *2402 | 97 | | 3098 |
| *2403 | 55 | 4 | 282 |

There are over 90 known A*24 alleles, 69 code for different isoforms and 7 are nulls. A*2403 can also be detected as A2403 serotype.

### Associated disease

A24 has a secondary risk factor for myasthenia gravis, Buerger's disease. It is also associated with Type 1 Diabetes (T1D) and systemic lupus erythematosus (SLE).

### Alleles

A*2402 is a secondary risk factor, alters type 1 diabetes risk, and allele associated with thymoma-induced myasthenia gravis.

## Haplotypes

HLA A24-B35 haplotype by Cw frequencies :

| | | freq | | Rank in |
| - | - | - | - | - |
| ref. | Population | (%) | | Pop. |
| | Java (Indonesia) | 8.0 | $^1$ | 4 |
| | S. Amer. Native | 6.3 | $^1$ | 3 |
| | N. Amer. Native | 5.4 | $^1$ | 5 |
| | Mexican | 4.7 | $^1$ | |
| | Inuit | 4.2 | $^1$ | |
| | Brazilian | 3.8 | $^1$ | |
| | Austria | 3.5 | $^1$ | |
| | Portuguese | 3.1 | $^1$ | 3 |
| | Yakut | 2.9 | $^1$ | |
| | Mongolian | 2.7 | $^1$ | |
| | Timor | 2.5 | $^1$ | 5 |
| | Bharghavas (India) | 2.4 | $^1$ | |
| | Greek | 2.3 | $^1$ | |
| | Italian | 2.2 | $^1$ | |
| | Mongolian | 1.9 | $^1$ | |
| | Vietnamese | 1.8 | $^1$ | |
| | Japanese | 1.6 | $^2$ | |
| | French | 1.2 | $^2$ | |
| $^1$ Cw4. $^2$ Cw9. ||||

A24-Cw7-B39 A24-Cw10-B60 A24-Cw10-B61 A24-B48

### A24-Cw4-B35

This particular haplotype is common across a fairly wide region, possibly the most widely spread A-Cw-B haplotype in humans. Cw4-B35 has a node within the region once referred to as Thracia/Dacia.

### A24-Cw*14-B51

HLA A24-CBL-B51 (CBL=1402) haplotype frequencies :

| | | freq |
| - | - | - |
| ref. | Population | (%) |
| | Korean | 3.5 |
| | Iyers | 3.4 |
| | Mongolian | 2.9 |
| | Japanese | 2.6 |
| | Romanian | 2.2 |
| | Greek | 2.1 |
| | Hungarian | 2.0 |
| | Italian | 0.6 |
