RNPC3 and COVID-19: In a study analyzing the sera and plasma from 64 patients with COVID-19, approximately 25% of patients exhibited an autoantibody response on average 12.3 days after diagnosis, and the reactivity was primarily to nuclear antigens, including ribonucleoprotein (RNP) (n = 8), SSA, SSB, dsDNA, chromatin, or centromere (35).