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). Its 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.