Pathogenic mutations have been identified in genes encoding other components of the TGF-β/bone morphogenetic protein (BMP) signaling pathways, including ACVRL1, ENG, GDF2 [5], SMAD9, and CAV1, providing compelling evidence for a central role of dysregulated BMP signaling in PAH pathogenesis [2]. The gene discussed is ENG; the disease is pulmonary arterial hypertension.