BLOOD GROUPS 61 



C and c hchave like alleles, the possibility of a C-negative c-negative 

 grouping does not exist.) Use of anti-E and anti-e further sub- 

 divides each of these three types into three others, and the use of 

 anti-D subdivides all types once more into D-positive and D-negative. 

 Thus, eighteen types (3 X 3 X 2 = 18) of Rh antigen can be 

 distinguished. If anti-e is not available, as is usually the case, he 

 number of Rh types becomes twelve (3 X 2 X 2 = 12) (Table 4-4). 

 Variants of these antigens, described by the British workers as 

 further alleles, have been found, and antigens which seem to be due 

 to other gene loci on the same chromosome are known. A rare type 

 of blood, classified D, which contains only the D antigen, has been 

 found. 



TABLE 4-4 

 Reactions of the Twelve Rh Blood Groups Distinguished by Four Anti-Rh Sera 



The frequencies of the occurrence of Rh antigens vary widely in 

 different populations. The Rh-negative type (cde) is most strikingly 

 absent from Asian and Pacific populations and the American Indians. 

 It has its highest frequency in the Basques, a population in certain 

 regions of France and Spain, and certain inhabitants of Switzerland. 

 The Basques speak a non-Indo-European language and are known 

 to represent the remnant of an earlier European population which 

 was once dispersed over a much wider area, including perhaps North 



