HLA-A23

See also: History and naming of human leukocyte antigens

HLA-A23 (A23) is a human leukocyte antigen serotype within HLA-A serotype group. The serotype is determined by the antibody recognition of α²³ subset of HLA-A α-chains. For A23, the alpha, "A", chain are encoded by the HLA-A*23 allele group and the β-chain are encoded by B2M locus.^[1] This group currently is dominated by A*2301. A23 and A*23 are almost synonymous in meaning. A23 is a split antigen of the broad antigen HLA-A9 and it is a sister serotype of HLA-A24.

HLA-A23
(MHC Class I, A cell surface antigen)
HLA-A23
About
Protein	transmembrane receptor/ligand
Structure	αβ heterodimer
Subunits	HLA-A*2301, β2-microglobulin
Older names	HL-A9
Subtypes
Subtype allele Available structures A23 *2301
Alleles link-out to IMGT/HLA database at EBI

A23 is common in Africa and regions of the Middle East, Mediterranean, and India than Europe, East Asia or the Americas.

Serotype

A23 recognition of some HLA A*23 gene products^[2]

A*23	A23	A24	Sample
allele	%	%	size (N)
*2301	95	1	5119

Allele

HLA A*2301 frequencies

Study population	Freq.  (in %)[3]
Mali Bandiagara	22.8
Cameroon Yaounde	18.7
Senegal Niokholo Mandenka	17.7
Guinea Bissau	15.6
Cameroon Bamileke	14.9
Cape Verde Southeastern I…	14.8
Cameroon Beti	13.5
Zimbabwe Harare Shona	12.7
USA African America	11.1
Portugal North	10.9
South African Natal Zulu	10.0
Cuban Mulatto	9.5
Tunisia	9.4
Kenya Luo	8.9
Morocco Berber Nador Meta…	8.2
Zambia Lusaka	8.1
China Beijing	7.5
Kenya Nandi	7.1
Uganda Kampala	6.8
Georgia Tbilisi Kurds	6.7
Portugal South	6.1
Sudanese	5.8
Bulgaria	5.5
Israel Arab Druse	5.5
Saudi Arabia Guraiat and …	5.4
Spain Catalonia Girona	4.6
Kenya	4.5
Venezuela Caracus	4.0
USA South Texas Hispanics	3.9
Mexico Mestizos	3.7
Russia Tuva pop 2	2.9
Romanian	2.5
Croatia	2.3
Brazil	2.0
Spain Basque Gipuzkoa Pro…	2.0
Australia New South Wales	1.9
Czech Republic	1.9
Georgia Tbilisi Georgian…	1.9
Oman	1.7
Belgium	1.6
USA North American Native…	1.6
China Inner Mongolia	1.5
India New Delhi	1.5
Pakistan Pathan	1.5
Ireland Northern	1.4
Jordan Amman	1.4
Mongolia Buriat	1.4
Pakistan Sindhi	1.3
USA Caucasian (2)	1.3
France South East	1.2
Italy North Pavia	1.2
Iran Baloch	1.1
Italy Bergamo	1.1
France Corsica	1.0
India North Hindus	1.0
Portugal Centre	1.0
Allele frequencies presented, only

Haplotypes

A23-B7 is found in N.Afr. and S.Afr non-caucasians.
A23-B44 is found in Albania, Zimbabwe, Morocco, Spain and Danes.
A23-B58 is found in the !kung and Zaire.

Associated diseases

A*23:Cw*07 is associated with higher viral load in HIV^[4]