BMPR2 and idiopathic pulmonary arterial hypertension: It is well known that patients with idiopathic pulmonary arterial hypertension (IPAH) having an underlying genetic predisposition and patients with hereditary pulmonary arterial hypertension (HPAH) have an inheritable genetic mutation of which BMPR2 is the most common one, seen in about 80% of the cases of HPAH.