Recent evolution of the mutation rate and spectrum in Europeans

Recent evolution of the mutation rate and spectrum in Europeans
Kelley Harris
doi: http://dx.doi.org/10.1101/010314

As humans dispersed out of Africa, they adapted to new environmental challenges including changes in exposure to mutagenic solar radiation. This raises the possibility that different populations experienced different selective pressures affecting genome integrity. Prior work has uncovered divergent selection in tropical versus temperate latitudes on eQTLs that regulate the DNA damage response, as well as evidence that the human mutation rate per year has changed at least 2-fold since we shared a common ancestor with chimpanzees. Here, I present evidence that the rate of a particular mutation type has recently increased in the European lineage, rising in frequency by 50% during the 30,000–50,000 years since Europeans diverged from Asians. A comparison of single nucleotide polymorphisms (SNPs) private to Africa, Asia, and Europe in the 1000 Genomes data reveals that private European variation is enriched for the transition 5’-TCC-3’→5’-TTC-3’. Although it is not clear whether UV played a causal role in the changing the European mutational spectrum, 5’-TCC-3’→5’-TTC-3’ is known to be the most common somatic mutation present in melanoma skin cancers, as well as the mutation most frequently induced in vitro by UV. Regardless of its causality, this change indicates that DNA replication fidelity has not remained stable even since the origin of modern humans and might have changed numerous times during our recent evolutionary history.

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