BMPR2 and pulmonary arterial hypertension: In 2000, heterozygous germline mutations in the gene encoding the bone morphogenetic protein receptor type II (BMPR2) were identified as the main genetic cause of familial PAH.5, 6 Over 300 different BMPR2 mutations have been identified with a prevalence of greater than 75% in families with PAH.7, 8 BMPR-II is a receptor for the bone morphogenetic proteins (members of the transforming growth factor-β superfamily).