An unusual Rh phenotype indicating heterogeneity of the Cw antigen

A family is reported in which a new Cw antigen occurred in two generations. This was recognized by 17 anti-Cw sera, but by none of the 21 anti-C sera which were, however, shown to react strongly with common Cw+ cells. This unusual finding provides evidence that the Cw antigen is in fact heterogeneous. On the basis of data obtained from absorption-elution and coagglutination studies a tentative explanation is attempted: common Cw+ phenotypes are assumed to be Cw (+1+2) and the present phenotype Cw (+1-2). Anti-Cw sera should accordingly be anti-Cw1, whereas anti-C sera should only react with Cw2.