Comparison of allele O sequences of the human and non-human primate ABO system

Like humans, non-human primates express the antigens A and B of the ABO his toblood group system. In chimpanzees, only A and O types are found, while t he types A, B, AB, and O are found in macaques. The sequences of exons 6 an d 7 of two chimpanzee O alleles (O-del and O-x), two macaque species O alle les (rhesus monkey and crab-eating macaque), and sequences of exon 7 of two major chimpanzee A alleles (A(1ch) and A(2ch)) were established. The seque nces of cDNAs corresponding to the chimpanzee and rhesus monkey O alleles w ere characterized from exon 1 to 7 and from exon 4 to 7, respectively. A co mparison of our results with ABO gene sequences already published by others demonstrates that human and non-human primate O alleles are species-specif ic and result from independent silencing mutations. These observations rein force the hypothesis that the maintenance of the ABO gene polymorphism in p rimates reflects convergent evolution more than transpecies inheritance of ancestor alleles.