HLA-A23
HLA-A23 (A23) is a human leukocyte antigen "serotype" within HLA-A serotype group. The serotype is determined by the antibody recognition of α subset of HLA-A α-chains. For A23, the alpha, "A", chain are encoded by the HLA-A allele group and the β-chain are encoded by B2M locus. This group currently is dominated by A*2301. A23 and A 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. A23 is common in Africa and regions of the  Middle East, Mediterranean, and India than Europe, East Asia or the Americas. 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