SMAD9 and pulmonary arterial hypertension: According to the pulmonary hypertension gene curation expert panel of pulmonary hypertension of ClinGen [14], the association of BMPR2, KCNK3, KDR, SMAD9, and TBX4 and PH is definitive, GDF2 is strong, and AQP1 has a limited disease relationship.