SMAD4 and hereditary hemorrhagic telangiectasia: To determine whether including RASA1 and/or GDF2 in molecular testing for HHT increases diagnostic yield, the full coding regions of these two genes were analyzed from 93 patients suspected to have HHT, but tested negative for mutations in ENG, ACVRL1 and SMAD4. A custom multiplex primer-based target enrichment assay coupled with NGS was utilized to detect variants in the patient samples.