TGFB1 and hereditary hemorrhagic telangiectasia: The fact that HHT-1 is based on Endoglin mutations and HHT-2 is based on ALK1 mutations, both components of the TGF-β-pathway, account for ~85% of clinically diagnosed HHT patients implies that TGF-β is a critical component in this disease [59,60,61,62].