Common homozygosity for predicted loss-of-function variants reveals both redundant and advantageous effects of dispensable human genes

Significance Human genes homozygous for apparent loss of function (LoF) variants are increasingly reported in a sizeable proportion of individuals without overt clinical phenotypes. Here, we found 166 genes with 179 predicted LoF variants for which the frequency of homozygous individuals exceeds 1% in at least one of the populations present in databases ExAC and gnomAD. These putatively dispensable genes showed relaxation of selective constraints, suggesting that a considerable proportion of these genes may be undergoing pseudogenization. Eight of these LoF variants displayed robust signals of positive selection, including two variants in genes involved in resistance to infectious diseases. The identification of dispensable genes will facilitate the identification of functions that are now redundant, or possibly even advantageous, for human survival.