The Hey antigen and antibody. A second family study and the first example of an IgG anti-Hey.

A three generation family with 16 members shows that the Hey red blood cell antigen is not in the Rh, P or Kidd systems. The mother of the proband was found to have an IgG component in her anti-Hey, probably the result of alloimmunization by her two Hey-positive children. the wife of the proband who had 1 Hey-positive child, and 4 recipients of a single unit of Hey-positive blood did not have detectable anti-Hey. The presence of the IgG component of the mother's anti-Hey raises the possibility that both hemolytic disease of the newborn (HDN) and hemolytic transfusion reactions (HTR) could occur due to anti-Hey.