HLA-A68

Disease associations

By allele

A*68 is associated with higher viral load in HIV. A68 may be protective against symptomatic heart disease in Chaga's cardiomyopathy.

Allele frequencies

A68 can be subdivided into 3 alleles, *6801, *6802, *6803. *6801 can also be subdivided into *680101 and *680102 (previously called *68011 and *68012).

A*6801

A*6801 is higher in certain Native American groups, South Asian peoples, African peoples, however 6801 is at low levels in most of SE Asia, particularly the indigenous populations. This is also reflected by low levels along the West Pacific Rim including Japan. The hiatus of 6801 breaks in Northern Japan with the 3% frequency found in the Ainu, which continues to increase with Arctic peoples and falls of in Native Americans. Whereas in the Western Eurasia's northern regions, A6801 falls off. In both Africa and the New World both A680101 and A680102 can be found. Although in the New World A680102 is more prevalent.

A*6802

A*6802 has a global node within certain native peoples of South America, at 37%. A secondary node can be found in Africa. Like *6801 there is an hiatus of *6802 in SE Asia's indigenous populations, indicating that this population is not a likely source within the native peoples of the New World. Levels are generally low (

A*6803

A*6803 can be found in native peoples of the New World and in Central Asia, in Africa it appears to be limited to West and Central Africans. This distribution along with the information on 6801 and 6802 suggests a probable redistribution of *68 alleles from Africa after the initial migration from East Africa that colonized Southeast Asia. It also provides support for 2 waves of migration from Asia to the New World or, at minimum, an unknown mixing area of West Pacific Rim haplotypes and West African/Middle Eastern derived haplotypes in Eastern Asia before the first migration. At present the incursion of Western Eurasian peoples into East Asia follows evidence for reuse of transbaikal region after 18,300 years and correlates with the incipient Jōmon period of Japan several thousands of years later. Certain alleles and haplotypes of HLA in South Americans target Japan's estimated pre-Yayoi composition, but other peoples, for example in western Mexico are most similar to the Ainu and the peoples of the Amur basin.

A*6805

A*6805 is found in the Guatemalan and Central African Mbenzele at low levels.

A68 haplotypes

The genetic distance between Native Americans and Eurasians is too great for the persistence of shared haplotypes, particularly in light of the lower levels in most of Siberia. The link of haplotypes with Western Africa may be significant, and may indicate a rapid eastward migration and admixing within the late Paleolithic period.

Indigenous American haplotypes

A*680102-B35 haplotypes

• A680102 Cw0304 B*3506 (A68-Cw10-B35)
• A68-Cw4-B35 (Terena, Seri (Mexico))
  • A680102 Cw0401 B3521 (A68-Cw4-B35) (Terena)

A*6802-B35

• A*6802-B3501 Guadalajara
• A*6802-B3502 Guadalajara

A68-B35 Mayan (A*6803).

These two haplotypes are consistent with the presence of Cw4-B35 and A68 in Asia and Middle East and A68-B35 maybe the ancestral A68 haplotype. A28(A*6802)-B35 is found in Senegal.

A6801-B4002/4 - Terena, Eskimo, Mestizo, Tribal Indians (Asia)

A680102-B520102 in the Mexican Mestizo population. A28(A*6802)-B52 is also found in Senegal.

Old World A68 haplotypes

A28(~A68)-B51 Armenia, Senegal, Eskimo

A28(~A68)-B70 W. Afr, Zaire, Zimbabwe, N. and S. African (Non-caucasians), Khoi (Hottentot)

References

References

1. (2002). "Favorable and Unfavorable HLA Class I Alleles and Haplotypes in Zambians Predominantly Infected with Clade C Human Immunodeficiency Virus Type 1". J Virol.
2. Gostick E. (2007). "Functional and biophysical characterization of an HLA-A*6801-restricted HIV-specific T cell receptor". Eur. J. Immunol..
3. (2004). "MHC class I and class II genes in Mexican patients with Chagas disease". Hum. Immunol..
4. (2003). "New allele frequency database". Tissue Antigens.
5. Layrisse Z. (2001). "Extended HLA haplotypes in a Carib Amerindian population: the Yucpa of the Perija Range". Hum. Immunol..
6. Cao K. (2004). "Differentiation between African populations is evidenced by the diversity of alleles and haplotypes of HLA class I loci". Tissue Antigens.
7. Luo M. (2002). "HLA-A and HLA-B in Kenya, Africa: allele frequencies and identification of HLA-B1567 and HLA-B4426". Tissue Antigens.
8. (2003). "New allele frequency database". Tissue Antigens.
9. Middleton D. (2000). "Analysis of the distribution of HLA-A alleles in populations from five continents". Hum. Immunol..
10. Torimiro JN. (2006). "HLA class I diversity among rural rainforest inhabitants in Cameroon: identification of A2612-B4407 haplotype". Tissue Antigens.
11. (2005). "HLA-A and HLA-B allele frequencies in a mestizo population from Guadalajara, Mexico, determined by sequence-based typing". Tissue Antigens.
12. (2005). "HLA polymorphisms in Cabo Verde and Guiné-Bissau inferred from sequence-based typing". Hum. Immunol..
13. Oumhani K. (2002). "Sequence-Based analysis of the HLA-DRB1 polymorphism in Metalsa Berber and Chaouya Arabic-speaking groups from Morocco". Hum. Immunol..
14. Modiano D. (2001). "HLA class I in three West African ethnic groups: genetic distances from sub-Saharan and Caucasoid populations". Tissue Antigens.
15. Gómez-Casado E. (2003). "Origin of Mayans according to HLA genes and the uniqueness of Amerindians". Tissue Antigens.
16. Bruges Armas J. (2003). "HLA class I variation in the West African Pygmies and their genetic relationship with other African populations". Tissue Antigens.
17. Williams F. (2001). "Analysis of the distribution of HLA-B alleles in populations from five continents". Hum. Immunol..
18. (2004). "HLA alleles and haplotypes among the Lakota Sioux: report of the ASHI minority workshops, part III". Hum. Immunol..
19. Leffell MS. (2002). "HLA antigens, alleles and haplotypes among the Yup'ik Alaska natives: report of the ASHI Minority Workshops, Part II". Hum. Immunol..
20. A69]] is not widely distributed in Africa (mainly levant, cape verde islands, certain tribes in Burkino Faso), A28 frequencies can generally be treated as A68 frequencies]