The Rhesus Blood Groups 293 



of feeble-mindedness have indicated that some of the Rh-positive 

 children who survived may be feeble-minded, for preliminary 

 studies have shown that in two groups of feeble-minded children, 

 a considerably higher percentage were Rh-positive children whose 

 mothers were Rh-negative than would be found in a population 

 of normal individuals. A further study of a number of patients 

 who had a hemolytic reaction to blood transfusions of a homol- 

 ogous blood group and of mothers of erythroblastotic babies 

 showed that the Rh-positive individuals actually included a 

 number of different types or subtypes. All of them were Rh- 

 positive and were apparently determined by a series of five al- 

 leles, all of which were allelic to the recessive gene r. During 

 the course of these studies the symbols for the various genes 

 have been modified as increasing knowledge of the phenomena 

 were obtained, but the symbols adopted by Wiener (1946) will 

 be used here. 



Gene r is recessive to all the other genes in this series of mul- 

 tiple alleles. It produces no agglutinogen and reacts with no 

 agglutinin. Gene r^ produces agglutinogen Rho and reacts posi- 

 tively with anti-Rho agglutinin. Gene R' produces agglutinogen 

 Rh' and reacts with anti-Rl/ agglutinin. Gene R^ produces 

 both Rho and Rh' agglutinogens and reacts with both anti-Rho 

 and anti-Rh' antibodies. Gene R'' produces Rh'' agglutinogen 

 and reacts with antisera containing the anti-Rh" agglutinin, 

 whereas gene i?- results in the presence of both Rho and Rh'' 

 agglutinogens and reacts with both antibodies, anti-Rho and 

 anti-Rh". None of these genes is dominant to any other, but 

 all are dominant to r. 



Twenty-one theoretically possible genotypes can result from 

 these six alleles and are listed in Table 14. They can produce 

 eight different phenotypes or rhesus blood types. Three anti- 

 bodies, anti-Rho, anti-Rh', and anti-Rh", have been found, and 

 may form five types of sera. Rh-antiserum anti-Rho has agglu- 

 tinin Rho, whereas anti-Rh' has agglutinin anti-Rh', and anti- 

 Rh" antiserum contains agglutinin Rh". Combinations of anti- 

 Rho antiserum may also be found with either of the other two 

 types, giving antiserum anti-Rho, Rh' (also called anti-Rhi) and 

 anti-Rho, Rh" (also designated as anti-Rh2). An interesting 

 feature of the genes that determine the Rh-types is that the 



