Of the families who remain ‘HHT gene negative’ after recruitment through WLGMC either with HHT or with pulmonary AVMs not meeting a clinical diagnosis of HHT, eight have atypical telangiectasia (ie, not meeting typical appearances, sites or onset/evolution for HHT), three have SMAD4-suggestive phenotypes of aortopathies and/or gastric polyposis, while a series of additional phenotypes are evident in individual families. The gene discussed is SMAD4; the disease is hereditary hemorrhagic telangiectasia.