Heterogeneity of the O alleles at the blood group

Background and objectives: Amerindians are blood group O, but the distribution of the various O alleles is unknown. Their ABO genotypes were compared with samples from other Brazilian ethnic groups, Materials and methods: Genomic DNA was examined by PCR-RFLP analysis, PCR-SSP and direct sequencing. Results: An unusual allele distribution was found, with 91% of the O alleles being O-lvariant. Almost half of these alleles had an additional novel mutation (G542A), which was also detected in a few other Brazilian and European samples. The O alleles correlated completeley with ABO-related haplotypes previously determined by Southern blot. Conclusion: The three Amerindian tribes represent a homogeneous (ABO blood group) population, except for the G542A mutation. The presence of this mutation in all other populations examined suggests that it originated before the migration of man into America.