SOS1 and atrial septal defect: Previous studies comparing physical phenotypes of individuals with PTPN11 or SOS1 have found that pulmonary stenosis, atrial septal defects, short stature, and significant developmental delays are less prevalent in SOS1 relative to PTPN11. These differing phenotypes suggest that disruptions caused by PTPN11 and SOS1 variants at the molecular level may have overlapping, yet distinct, features [14, 15].