ACVRL1 and hereditary hemorrhagic telangiectasia: The cases reported here and by Liu et al., (2020) combined with previous cases of individuals with heterozygous GDF2 mutations (Wooderchak‐Donahue et al., 2013) suggest that GDF2 mutations can cause a syndrome that resembles HHT, but is nonetheless distinct from HHT caused by mutations in ACVRL1, ENG, or SMAD4.