Recruitment to date remains strong within the Vasculitis Natural History Study despite challenges imposed by the ongoing pandemic. All patients seen at the NIH Clinical Center receive comprehensive clinical evaluation and contribute samples to a growing biobank. Over the last few years, we have mainly focused on two forms of vasculitis: large vessel vasculitis (LVV) and relapsing polychondritis (RP). We have currently evaluated more than 800 patients with vasculitis under an observational protocol (14-AR-0200) and continue to see approximately 100 new patients each year in addition to following selected patients over time. Since the last report, we continue to publish articles on the role of vascular imaging as a biomarker of disease activity in large-vessel vasculitis (LVV). Giant cell arteritis (GCA) and Takayasu's arteritis (TAK) are the two major forms of large-vessel vasculitis (LVV), defined by inflammation of the aorta and primary branches. Clinical assessment of disease activity in LVV can be challenging, thus posing a barrier to effective monitoring and treatment. Patients with LVV can develop new vascular lesions during periods of apparent sustained clinical remission with normal inflammatory markers. While several studies have examined the potential of molecular imaging in LVV, the role of FDG-PET to detect vascular inflammation, monitor disease activity over time, and predict clinical outcomes remains unclear. In the past year, we have reported on longitudinal data within the cohort to show trends in vascular inflammation over time and to investigate whether vascular inflammation detected by FDG-PET has prognostic value. We have provided some of the only data available in the world on the relationship of PET scan findings and future disease progression. Work from our group continues to shape standard of care for clinical disease activity assessment in LVV, to influence novel trial designs to test therapeutic efficacy, and to inform researchers about the natural history of the disease. We also continue to investigate relapsing polychondritis in a prospective observational cohort study. Relapsing polychondritis is a multisystem, rheumatologic disease characterized by inflammation of cartilaginous structures including the ear, nose, joints and airways. There are currently no diagnostic tests for RP, organ involvement is variable, and diagnosis is dependent on the identification of a pattern of clinical features that can be, at times, quite subtle. RP has a large impact on mortality and morbidity with a high rate of organ damage and resultant disability. Airway involvement can render patients with RP unable to communicate, struggling to breath, and dependent on a tracheostomy for survival. We have evaluated over 100 patients with RP at the NIH Clinical Center over the last five years. All patients undergo comprehensive disease-specific clinical assessment including a detailed history and physical examination, audiometry, direct laryngoscopy, pulmonary function tests with oscillometry, and magnetic resonance imaging of the neck. In addition, we developed a novel method to perform dynamic computed tomography (CT) of the chest as a non-invasive way to detect structural damage to large airways. We anticipate that this cohort will be a rich source of clinical information for years to come as we begin to prospectively characterize this complex, heterogeneous disease. In addition to clinically profiling RP, we collect and bank biospecimens for use in future mechanistic studies. Over the last year, we continue to define a new disease that was discovered in our cohort known as the VEXAS (vacuole, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. VEXAS is caused by somatic mutations in UBA1 in bone marrow in adult patients with life-threatening multisystem disease. We recently identified prognostic factors for survival and underlying the mechanistic basis for these associations. We are working to define treatment options for this frequently fatal disease, including implementation of a bone marrow transplantation protocol at the NIH in collaboration with our hematology colleagues. We are helping to lead worldwide efforts to define this new disease in terms of clinical manifestations, diagnostic algorithms, treatment, and epidemiologic studies. Finally, in light of the ongoing pandemic, we are participating in research designed to assess the impact of COVID-19 on patients with autoimmune diseases, including vasculitis. These efforts have included both patient-based surveys designed to assess the impact of the pandemic on health-related behavior and outcomes in patients with vasculitis as well as mechanistic studies to determine immune responses in patients with vasculitis who are exposed to SARS-COV-2. Mechanistic work is being conducted under a collaborative initiative at the Intramural NIH Program led by Dr. Mariana Kaplan.