CHARACTERIZATION OF THE ABO BLOOD-GROUP GENES IN MACAQUES - EVIDENCE FOR CONVERGENT EVOLUTION

The ABO blood group system is known to act as a major transplantation barrier in primates. Different primate species share the presence of A and B antigens. The polymorphism of the macaque ABO blood group genes was analyzed by cloning and sequencing the exon 7 region. In the case of the rhesus macaque (Macaca mulatta) and cynomolgus monkey (Macaca fascicularis) we were able to identify ABO blood group gene segments w hich cluster into two lineages, namely: A/*O1 and *B. In addition all elic variation was observed. The 2 amino acid replacements at position s 266 and 268, which are thought to be crucial for A or B transferase activity, could be confirmed for both macaque species. Comparison of p rimate sequences shows that A and B reactivity was generated independe ntly from each other in the hominoids and Old World monkey lineages. H ence, the primate A and B blood group genes are subject to convergent evolution.