Recombination between the X and Y chromosomes: implications for the relationship between MIC2, XG and YG.

Three loci affect the levels of expression of the 12E7 antigen on red blood cells: MIC2, the pseudoautosomal structural gene for the 12E7 antigen; XG, an X-linked red cell blood group locus and YG, a polymorphic Y-linked locus. In this report we describe recombination between XG and MIC2 and an exchange between the X and Y chromosomes which included YG. These results have prompted us to propose a new model describing the genetic relationship between the XGa and 12E7 antigens.