BMPR2 and pulmonary arterial hypertension: In this way, a breakthrough in understanding the pathogenic role of BMP signaling impairment in PAH development was the discovery of the heterozygous germline mutations in the gene encoding the type 2 receptor of the BMP signaling pathway (BMPR2), which are responsible for over 70% of heritable PAH cases and near 15–20% of nonheritable PAH cases [34].