BMPR2 and pulmonary arterial hypertension: PAH has been defined as pulmonary artery pressure (PAP) ≥ 25 mmHg at rest and occurs as a result of multiple causes, such as heritable factors (mainly bone morphogenic protein receptor-2 (BMPR2) mutations), drugs and toxins, as well as association with other diseases; however, PAH without known causes is known as idiopathic PAH (IPAH) [14,17].