Anti-VEGFA therapy (bevacizumab) originally given to HHT patients for concurrent cancer led to a marked improvement of HHT disease symptoms42,43 and was followed up recently in a successful phase 2 clinical trial in a small number of HHT2 patients with HOHF.44 However, there is little understanding of the molecular interaction of VEGF signaling and disrupted BMP9 signaling in HHT, which is essential to optimize and improve these therapies. This evidence concerns the gene VEGFA and hereditary hemorrhagic telangiectasia.