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ABO Genetic Summary

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Summary:
The polymorphism of blood types in the ABO blood group has been suspected to be under balancing selection. In order to test this hypothesis, the authors of the article analyzed two datasets of gene sequences in O alleles, one originating from an SNP project in Seattle and the other collected from seven populations worldwide. From conducting a phylogenetic analysis of the sequences, they found that there were four main lineages, and that the mutation giving rise to the O allele likely emerged at least three different times in human evolution, splitting into lineages O02, O01, and O09. However, they also found that the genealogy changes along the gene, both in the number of variations and branches, and their time depth, which suggests that both selection and recombination acted on the alleles. This, along with tests for neutral evolution that the researchers conducted, allowed them to conclude that balancing selection occurred on the ABO gene and that neutral evolution could not have occurred, especially in a region of the sequence …show more content…

One was produced by the Seattle SNPs Project and sequenced 320 genes in 24 African-Americans and 23 European-Americans, all unrelated to each other to reduce the effects of having similar sequences catalogued more than once. Using analysis software PHASE, each haplotype was classified according to an identifying allele and lineage, and was grouped with similar haplotypes, and phylogenetic trees with the maximum likelihood of being correct were constructed and selected by a different software, PHYML. The researchers took any pattern in which a haplotype departed from the average consensus sequence of its lineage as an indication that recombination or gene conversion occurred. Deviation from neutral evolution was tested with an F test, quantifying differences between empirical data on sequence change and what would be expected from neutral evolution as shown in

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