ACVRL1 and hereditary hemorrhagic telangiectasia: In conclusion, mice heterozygous for endoglin or endothelium specific deletion of endoglin resembling HHT-1 (Arthur et al., 2000; Choi et al., 2012, 2014) and animals heterozygous for ALK1 mice resembling HHT-2 (Srinivasan et al., 2003), are suitable mouse models to unravel the etiology and mechanism behind HHT.