ACVRL1 and hereditary hemorrhagic telangiectasia: Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is an autosomal dominant disorder characterized by multiple arteriovenous malformations (AVMs).57The condition is most commonly associated with variants in three genes:ENG(OMIM 131195, endoglin),ACVRL1(OMIM 601284, activin A receptor type II-like 1), andSMAD4(OMIM 600993).57, 58The prevalence in North America is ∼ 1 in 10,000 individuals.57