Just ten years ago, Levine and Stetson discovered an atypical immune agglutinin in the serum of a woman after stillbirth. In 1940, Landsteiner and Wiener discovered a new antigen in erythrocytes, which they called Rh. Subsequently, it was demonstrated that immune body reactions were responsible for certain hemolytic reactions in transfusions and for the occurrence of erythroblastosis fetalis. The Rh groups were studied intensively by American and British workers, under the stimulus of the wartime expansion of blood transfusion services. The genetic relationships of the various Rh groups were anticipated, and, in fact, several genotypes were predicted prior to their actual discovery.
In 1943 the British geneticist, R. A. Fischer, made a theoretic analysis of the problem and concluded that the presence of three closely linked genes in one pair of chromosomes could explain the observations. These he designated C, D and E. It is possible to specify the genetic