There are a number of clinical subtypes of PAH, including: idiopathic PAH; PAH associated with another disease, typically connective tissue diseases and congenital heart diseases (CHD) with large systemic to pulmonary arterial shunts; and heritable (H) PAH, which is most commonly caused by mutations in the bone morphogenetic protein receptor type II (Bmpr2) gene. Here, BMPR2 is linked to congenital heart disease.