As hereditary hemorrhagic telangiectasia is classified according to mutations of either the ENG or ACVRL1 genes, the phenotype has also been reported to vary in HHT1, and HHT2, such as pulmonary AVMs, vary more commonly in HHT1, while hepatic AVMs vary in HHT2 (20,22). This evidence concerns the gene ACVRL1 and hereditary hemorrhagic telangiectasia.