HHT is related to deleterious variants in 2 major genes: ENG (OMIM 131195) that encodes endoglin and which is located on chromosome 9q and causes HHT1 (OMIM 187300), and ACVRL1 (OMIM 601284) that encodes activin receptor-like kinase type 1 (ALK1), which is located on chromosome 12q and causes HHT2 (OMIM 600376) [2, 3]. Here, ACVRL1 is linked to hereditary hemorrhagic telangiectasia.