Another example of haemopoietic chimaerism in dizygotic twins.

Another example of haemopoietic chimaerism in dizygotic twins is described. Each twin had two distinct blood cell populations. The red cell populations differed in three blood group systems and in other genetic characters, and the white cell population in HLA types and in XX/XY karyotypes. The biological significance of these findings is discussed with special reference to the relative proportions of the two red and white cell populations, the ABH blood group gene-specified glycosyltransferase levels, and the HLA types.