Premature termination codons in modern human genomes

The considerable range of genetic variation in human populations may partly reflect distinctive processes of adaptation to variable environmental conditions. However, the adaptive genomic signatures remain to be completely elucidated. This research explores candidate loci under selection at the population level by characterizing recently arisen premature termination codons (PTCs), some of which indicate a human knockout. From a total of 7595 participants from two population exome projects, 246 PTCs were found where natural selection has resulted in new alleles with a high frequency (from 1% to 96%) of derived alleles and various levels of population differentiation (F-ST = 0.00139-0.626). The PTC genes formed protein and regulatory networks limited to 15 biological processes or gene families, of which seven categories were previously unreported. PTC mutations have a strong tendency to be introduced into members of the same gene family, even during modern human evolution, although the exact nature of the selection is not fully known. The findings here suggest the ongoing evolutionary plasticity of modern humans at the genetic level and also partly provide insights into common human knockouts.