Low complement levels (found in 50% of cases) during acute illness, positive ANA (in approximately 10% of cases), positive rheumatoid factors (in approximately 25% of cases), or positive anti-CCP (in approximately 5%) can be present in HBV-associated arthritis, which clinically mimics other diagnoses, such as RA, systemic lupus erythematosus (SLE), drug reaction, etc., and may lead to misdiagnosis [111,127]. Here, BTG3 is linked to systemic lupus erythematosus.