Exagen Inc. is a commercial-stage diagnostics company specializing in autoimmune testing solutions under the AVISE brand in the United States. It designs, develops, and commercializes testing products that enable healthcare providers to diagnose, prognose, and monitor complex rheumatic and autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and other connective tissue diseases (CTDs). The lead product, AVISE CTD, supports differential diagnosis for patients with overlapping symptoms of various CTDs. Exagen Inc. also offers specialized biomarkers, including those for seronegative rheumatoid arthritis like anti-PAD4 markers and urinary panels for lupus nephritis, enhancing clinical utility in rheumatology. These tests play a key role in improving patient care by facilitating timely interventions and optimizing therapeutic strategies within the autoimmune diagnostics market. Headquartered in Carlsbad, California, Exagen Inc. focuses on advancing laboratory testing adoption among rheumatologists and supports research through presentations at medical conferences.