Moreover, reduction of circulating TGF-β1 in patients with HHT-1 has been attributed to the reduction of TGF-β production by endothelial cells (ECs) due to reduced ENG levels, and this reduction affects the recruitment of SMCs to the vessel wall resulting in leaky and fragile vessels (21, 22). Here, TGFB1 is linked to telangiectasia, hereditary hemorrhagic, type 1.