After a genetic diagnosis, we found two de novo variants of PTPN11 in patients 3312205 and 3312291, and one de novo variant of the POLD1 gene in patient 3312343, which led to diagnoses of Noonan syndrome (MIM163950) and MDPL syndrome (mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome, MIM615381), respectively. The gene discussed is POLD1; the disease is Micrognathia.