 SAN DIEGO, Jan. 04, 2021 GLOBE NEWSWIRE -- Exagen Inc. Nasdaq: XGN, an organization dedicated to transforming the care continuum for patients suffering from autoimmune diseases, announced today that all AVISE test offerings CTD, Lupus, SLE Prognostic, SLE Monitor, APS, Vasculitis AAV, MTX, and HCQ are a contracted in-network service with St. Charles Health System, the largest provider of medical care in Central Oregon. 