XG antigen is a red blood cell surface antigen discovered in 1962. [1 ] [2 ]
The PBDX gene that encodes the
antigen is located on the short arm of the X chromosome. [3 ] Since males normally have one X chromosome they are considered [4 ] hemizygotes. Since women have two copies of the gene and could be heterozygotic for the presence or absence of the functioning gene they could (through the process of lyonisation) express the functioning protein on just some of their red blood cells.
^ Tippett P, Ellis NA (October 1998). "The Xg blood group system: a review". Transfus Med Rev 12 (4): 233–57. doi: 10.1016/S0887-7963(98)80001-1. PMID 9798268.
^ Mann JJ, Cahan A, Gelb AG, et al. A sex-linked blood group. Lancet. 1962;i:8.
^ Ellis NA, Tippett P, Petty A, et al. (November 1994). "PBDX is the XG blood group gene". Nat. Genet. 8 (3): 285–90. doi: 10.1038/ng1194-285. PMID 7533029.
^ LINDSTEN J, FRACCARO M, POLANI PE, HAMERTON JL, SANGER R, RACE RR (February 1963). "Evidence that the Xg blood group genes are on the short arm of the X chromosome". Nature 197 (4868): 648–9. doi: 10.1038/197648a0. PMID 13930842.