We have rechecked the exome data of the 3 patients for 17 genes known to be associated with PAH (BMPR2, EIF2AK4, TBX4, ATP13A3, GDF2, SOX17, AQP1, ACVRL1, SMAD9, ENG, KCNK3, CAV1, SMAD4, SMAD1, KLF2, BMPR1B, and KCNA5). Here, SMAD1 is linked to pulmonary arterial hypertension.