FGFR2 and Apert syndrome: These levels measured in sperm are in line with those previously observed for other PAE disorders—for example, the FGFR2-causing Apert syndrome c.755C>G (GenBank: NM_000141.5) (p.Ser252Trp) change (estimated to account for ∼1:100,000 births) was quantified at an average level of ∼1:40,000 in sperm of a cohort of men aged on average 39.1 years (median age = 37.0 [range: 24–73 years]).8