Relative Frequencies of the Two O Alleles of the Histo‐Blood ABH System in Different Racial Groups

O blood group results from the absence of glycosyltransferase activity, which is due most commonly to a single nucleotide deletion in the glycosyltransferase gene. A second type of O allele resulting from three nucleotide substitutions in the glycosyltransferase gene had its frequency recently determined in a Danish population. However, its frequency among different human populations is not known. The frequencies of the two types of O alleles were determined by DNA analysis of the glycosyltransferase gene of group O individuals of three racial groups (Caucasians, blacks and Amerindians). The mean frequency of carriers of the three-base mutation group O gene among blacks and Caucasians is 4.7%; the mutation was not observed among 100 Amerindian chromosomes. The data reveal the relative frequencies of O alleles in different racial groups, and demonstrate that the origin of this variant predates racial divergence, since it is found equally among blacks and whites.