SOX17 and pulmonary arterial hypertension: This approach revealed a significant association of rare variation in the aquaporin gene, AQP1, and the transcription factor encoded by SOX17. Of note, both AQP1 and SOX17 were within the top 8 ranked genes in our combined PTV and missense burden test analysis (Supplementary Table 7), providing further confidence in their causative contribution to PAH.