BMPR2 and idiopathic pulmonary arterial hypertension: For example, the female-to-male ratio is currently reported in the REVEAL Registry as approximately 4.1:1 for idiopathic PAH (IPAH) and 3.8:1 for associated PAH (APAH).1,2 Dysfunctional bone morphogenetic protein receptor 2 (BMPR2) signalling is recognized to play a pivotal role in the development of PAH and mutations in BMPR2 are responsible for ∼80% of heritable PAH (HPAH) cases.3