The rare blood group antigen, Wu.

The inheritance of the Wu antigen in three families is described. The observations suggest that the antigen is inherited as a Mendelian dominant character. Wu segregates independently of sex and of the ABO, MNSs, Rh, Lutheran, Duffy and Kidd blood group systems. Independence of Kell is also quite likely. Wu is a very rare antigen. The corresponding antibody is not as infrequent. Anti-Wu occurs as a 'naturally occurring' antibody, often together with antibodies against other rare antigens.