BMPR2 and pulmonary arterial hypertension: BMPR2, bone morphogenetic protein receptor 2; ERA: endothelial receptor antagonist; IMPRES: Imatinib in Pulmonary Arterial Hypertension, a Randomized Efficacy Study; MWD, minute walking distance; PAH, pulmonary arterial hypertension; PATENT, Pulmonary Arterial Hypertension Soluble Guanylate Cyclase–Stimulator Trial; PDE-5i: phosphodiesterase 5 inhibitor, RCT, randomized controlled trial