The Comprehensive HHT Outcomes Registry of the United States (CHORUS) is an observational registry of patients diagnosed with Hereditary Hemorrhagic Telangiectasia (HHT). The purpose of this study is to better understand HHT, the symptoms and complications it causes, and the impact the disease has on people's lives. The investigators will collect long-term information about the participant, allowing us to understand how the disease changes over time, and what factors can influence those changes. Ultimately, this should help improve treatments for the disease. Another important goal of the study is to provide a way to contact people to participate in future clinical trials and other research. The registry will be a centralized resource for recruitment for clinical trials. People in the registry will not be obligated to join any of these additional studies, but if interested, can agree to be contacted if they may be eligible for a study. Participants will: * Be asked to provide permission to collect information from their medical records, including things like demographic information, diagnosis information, family history, test results, treatment information, symptoms, complications, lifestyle and other relevant medical information. * Be asked study-related questions by phone or at a clinic visit. * Be asked study-related questions every year after enrollment for up to 10 years or until the study ends. A member of the study team will communicate with participants by phone or at clinic visits to collect information regarding any changes to their health over the previous year/s including new test results, treatment information, symptoms, and complications from HHT.