CS can be caused by mutations in ERCC6 (CSB, [MIM: 609413]) or ERCC8 (CSA, [MIM: 609412]) while certain mutations in XPB (MIM: 610651), XPD (MIM: 278730) and XPG (MIM: 278780) genes also develop some CS clinical features4–7. The gene discussed is ERCC3; the disease is Cowden syndrome 1.