AVMs are hallmarks of HHT, a human disease caused by autosomal dominant mutations in genes of the TGF-β signaling pathway, in particular endoglin or ACVRL1 (activin receptor-like kinase 1).37 In HHT, AVMs commonly form in the nose, lungs, brain, or the liver and affected individuals often suffer from nasal and gastrointestinal bleedings. The gene discussed is ACVRL1; the disease is hereditary hemorrhagic telangiectasia.