Cloning approaches have revealed that the pathogenesis of pulmonary hypertension involves a set of susceptible genes, notably mutations in genes related to the transforming growth factor-β (TGF-β) pathway, such as bone morphogenic protein receptor type II (BMPR-II), activin receptor-like 1 (ACVRL1), and endoglin (ENG). The gene discussed is ENG; the disease is pulmonary hypertension.