Because RASA1 mutations have previously been associated with capillary and arteriovenous malformations similar to the HHT phenotype ([20][21]), and because no variants were identified in the ENG, ACVRL1, or SMAD4 genes, the RASA1 variant was assumed to be the causative mutation for this sample. The gene discussed is SMAD4; the disease is hereditary hemorrhagic telangiectasia.