According to the Nice classification of 2013, which succeeded the Dana Point classification, up to 80% of HPAH patients present with BMPR2 mutations, and an additional 5% present with mutations in other TGFβ superfamily genes, such as activin receptor-like kinase 1 (ALK1), endoglin (ENG), SMAD4, SMAD8, and caveolin1 (CAV1) [5]. The gene discussed is SMAD4; the disease is heritable pulmonary arterial hypertension.