Disruption of the BMP9/BMP10—ALK1/BMPR‐II signaling axis seems to underlie many cases of human PAH (Atkinson et al., 2002; Hodgson et al., 2019; Morrell et al., 2019) and is implicated in the pathogenesis of HHT caused by germ‐line ACVRL1 and ENG mutations (Kritharis et al., 2018). This evidence concerns the gene ENG and hereditary hemorrhagic telangiectasia.