PTPN11 and Abnormal cardiac septum morphology: Three children with atrial septal defects (P1–P3) were found to carry heterozygous variants (p.A72G, p.I282V, and p.P491S) of the PTPN11 gene, of which the p.I282V and p.491S variants were found in the parental samples, too, and are believed to be de novo mutations.