PTGIS and idiopathic pulmonary arterial hypertension: 11,12 Such a dysregulated prostacyclin axis would cause the apoptosis of lung endothelial cells and the remodeling of the pulmonary vasculature.24 In the present study, we identified 3 rare PTGIS variants that are overrepresented in patients with IPAH and without BMPR2 variants compared with healthy controls.