Subdivision of HL‐A5 and Comparative Studies of the HL‐A Polymorphism in South African Indians

The HL‐A5 antigen has a higher frequency in the Indian population than in either the Caucasian or Bantu populations of South Africa. Ninety‐five Asian Indians were tested by microcytotoxicity using 34 anti‐HL‐A5 and nine anti‐W5 sera. The results confirm the heterogeneity of the HL‐A5 antigen and show that it may be subdivided into at least four parts. The Indian population of South Africa is here subdivided into four groups. The HL‐A antigen frequencies in each group are compared, and haplotype frequencies and gametic associations (delta values) have been calculated. The genetic distances (f) between these groups and between Indians. Caucasians and Bantu also are calculated. The results may indicate a differential selection with respect to the HL‐A polymorphism.