TGFB1 and hereditary hemorrhagic telangiectasia: Previous studies have proposed that haploinsufficiency of HHT genes impairs the TGF-β1 signaling pathway, leading to abnormal vascular remodeling and angiogenesis where factors, such as VEGF or Ang-2, play a potential role in HHT angiodysplasia (Bernabeu et al., 2010).