Fig. 2.

Inferred sex and age dependencies of germline mutations (based on a linear model applied to trios with maternal age no greater than 40 y). In all panels, shaded areas and bars represent 95% CIs of the corresponding quantities obtained from bootstrapping. (A) Inferred sex-specific mutation rates as a function of parental ages. Parental ages are measured since birth, that is, birth corresponds to age 0 (throughout the paper). The extrapolated intercepts at age 0 are small but significantly positive for both sexes, implying a weak but significant effect of reproductive age on yearly mutation rates (16). (B) Predicted male-to-female mutation ratio (α) as a function of the ratio of paternal to maternal ages. For reference, the ratio of parental ages is centered around 1.10 in the deCODE DNM dataset (SD = 0.20). (C) Contrast between male-to-female mutation ratio (purple) and the ratio of male to female cell divisions (green), assuming the same paternal and maternal ages. Estimates of the cell division numbers for the two sexes in humans are from Drost and Lee (11).