SMAD4 and hereditary hemorrhagic telangiectasia: HHT associates with mutations in the endoglin (ENG) gene, also known as CD105 (39%–59% of cases), ACVRL1 gene (25%–57% of cases), or SMAD4 gene (1%–2%) in a subset of patients with HHT and juvenile polyposis (Viteri-Noël et al., 2022).