Proportion of chromosomes carrying at least one nonsynonymous or nonsense variant in the general human population. The red portion of the pie charts corresponds to the proportion of chromosomes carrying at least one nonsynonymous polymorphism, the black portion to the proportion of chromosomes carrying at least one nonsense polymorphism, and the blue portion to the proportion of chromosomes carrying neither nonsynonymous nor nonsense polymorphisms. Genes shaded in gray correspond to those encoding the receptor subunits of each IFN family.