MOLECULAR-BASES OF THE ABO BLOOD-GROUPS OF INDIANS FROM THE BRAZILIANAMAZON REGION

Phenotype studies of ABO blood groups in most Amerindian populations r evealed the exclusive presence of group O. Since group O is the result of the absence of glycosyltransferase activity, its molecular bases m ay be heterogeneous. We carried out ABO blood group genotyping by anal ysis of DNA of 30 Indians from 2 Amazonian tribes (Yanomami and Arara) , and compared the findings with other populations (Caucasians and Bla cks). Two segments of the glycosyltransferase gene were amplified by P CR and digested with KpnI or AluI to detect deletion or base change at positions 258 and 700, respectively. For all subjects, the gene basis of blood group O is the deletion of a single nucleotide at position 2 58 of the glycosyltransferase A gene, similar to that observed in Cauc asoids and Negroids. DNA sequencing of limited regions of the gene sup ports this conclusion. This finding does not exclude, however, that a heterogeneity of the O allele may be revealed by a more extensive anal ysis.