Interestingly, PAE mutations have been reported in various craniosynostosis syndromes caused by mutations in FGFR2 and FGFR3. It has been shown that PAE mutations are enriched over time because they confer a selective advantage to the mutant spermatogonial stem cells, leading to their clonal expansion. The gene discussed is FGFR2; the disease is craniosynostosis.