Exagen Inc. is a provider of autoimmune testing and its purpose as an organization is to provide clarity in autoimmune disease decision-making. The Company has developed and is commercializing a portfolio of testing products, under its AVISE brand. It commercially launched its testing product, AVISE CTD, which enables differential diagnosis for patients presenting with symptoms indicative of a variety of connective tissue diseases (CTDs) and other related diseases with overlapping symptoms. The comprehensive nature of AVISE CTD allows for the testing of various relevant biomarkers in one convenient blood draw. Included in AVISE CTD is its proprietary AVISE Lupus test, which enables the diagnosis of systemic lupus erythematosus (SLE) based on levels of erythrocyte bound C4d (EC4d) and B cell C4d (BC4d); along with anti-nuclear antibodies (ANA) and double-stranded DNA antibodies (ds-DNA). AVISE Lupus provides rheumatologists and their patients with sensitive and specific results.