Sperm mosaicism predicts transmission of de novo mutations to human blastocysts

De novo mutations underlie individually rare but collectively common pediatric congenital disorders. Some of these mutations can also be detected in tissues and from cells in a parent, where their abundance and tissue distribution can be measured. We previously reported that a subset of these mutations is detectable in sperm from the father, predicted to impact the health of offspring. Here, in three independent couples undergoing in vitro fertilization, we first assessed male gonadal mosaicism, then assessed the transmission of the mutations to their preimplantation blastocysts. We found an overall predictable transmission but slight under-transmission of mutations to blastocysts based upon measured mutational abundance in sperm, and we replicated this conclusion in an independent family-based cohort. Therefore, unbiased preimplantation genetic testing for gonadal mosaicism may represent a feasible approach to reduce the transmission of potentially harmful de novo mutations, which could help to reduce their impact on miscarriage and pediatric disease.