title: HLA-A23
text: # 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 $α^{23}$ 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. 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.
  
  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 :
  
  | A*23 | A23 | A24 | Sample |
  | - | - | - | - |
  | allele | % | % | size (N) |
  | *2301 | 95 | 1 | 5119 |
  
  ## 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
  
  