ACVRL1 and pulmonary arterial hypertension: Other genetic factors thought to be associated with PAH include mutations in endoglin (ENG), caveolin 1 (CAV1), potassium channel subfamily K member 3 (KCNK3), and the serine/threonine-protein kinase receptor R3, also referred to as Activin-like kinase type 2 receptor (ALK1; ACVRL1) (Archer et al., 2010).