Exagen Inc. develops and commercializes diagnostic testing solutions, leveraging its proprietary cell-bound complement activation products (CB-CAPs) technology under the AVISE brand throughout the United States. The company's mission is to equip rheumatologists with advanced tools for the precise diagnosis, prognosis, and ongoing management of autoimmune and related diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Its flagship product, AVISE CTD, aids in distinguishing between various connective tissue diseases (CTDs) and other conditions with overlapping symptoms in symptomatic patients. The company's product portfolio includes AVISE Lupus, which assesses complement system activation by measuring B-cell C4d and erythrocyte-bound C4d in blood. AVISE APS offers a comprehensive panel of autoantibody tests for the diagnosis and management of Antiphospholipid Syndrome (APS). For SLE patients, AVISE SLE Prognostic provides an autoantibody panel to evaluate the potential for kidney, brain, and cardiovascular complications. Additionally, AVISE Vasculitis AAV utilizes a testing panel of individual analytes to assist physicians in the assessment and monitoring of anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis, while AVISE Anti-CarP helps identify RA patients prone to severe disease, and AVISE PC4d measures platelet-bound C4d. Further offerings include AVISE SLE Monitor, a biomarker blood test; AVISE MTX, a patented and validated blood test; and AVISE HCQ, designed to monitor hydroxychloroquine levels. Exagen also holds a research collaboration and license agreement with Allegheny Health Network (AHN) Research Institute to advance the development of novel patented biomarkers. Incorporated in 2002, the company was formerly known as Exagen Diagnostics, Inc. before rebranding to Exagen Inc. in January 2019. Its headquarters are located in Vista, California.