Exagen Inc. designs, develops, and commercializes various testing products under the AVISE brand in the United States. The company enables healthcare providers to care for patients through the diagnosis, prognosis, and monitoring of complex rheumatic, and autoimmune and autoimmune-related diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). The company's lead testing product is AVISE CTD that enables differential diagnosis for patients presenting with symptoms indicative of various connective tissue diseases (CTDs) and other related diseases with overlapping symptoms. The company offers AVISE Lupus platform, a cornerstone of the SLE assessment that begins by quantifying the level of CB-CAPs biomarkers (EC4d and BC4d) in the patient's blood; and AVISE APS that aids in the diagnosis and management of APS. In addition, it provides AVISE Vasculitis AAV, which utilizes a testing panel of individual analytes to provide physicians with results in the assessment and monitoring of anti-neutrophil cytoplasmic antibody associated vasculitis; AVISE Anti-Histone, a test for autoantibodies to histone proteins; AVISE SLE Prognostic, a panel of autoantibodies for assessing the potential for complications affecting the kidney, brain, and cardiovascular system; and AVISE Anti-CarP, a biomarker-driven RA prognostic test. Further, the company offers AVISE SLE Monitor, a blood test that employs CB-CAPs technology; AVISE MTX, a patented and validated blood test; and AVISE HCQ, a blood test to monitor levels of hydroxychloroquine. It has a research collaboration and license agreement with Allegheny Health Network (AHN) Research Institute to develop T-Cell biomarkers. The company was formerly known as Exagen Diagnostics, Inc. and changed its name to Exagen Inc. in January 2019. Exagen Inc. was incorporated in 2002 and is headquartered in Vista, California.