The proportion of rare variants per base pair (bp) in each gene was higher (mean = 2.015%; 95% range = 0.621 to 4.057%) than that of common variants (0.334%; 95% range = 0.000 to 1.143%), and the average ratio of rare to common alleles per bp was ∼6:1. We identified 110 genes that showed an unusually high proportion of rare variants, including six histone genes that are likely subject to greater selective constraint (table S3). The number of putatively functional variants also varied widely across genes (fig. S14B), ranging from 0 to >100, with a median of two in both EA and AA samples.
