To identify undiagnosed autoimmunity, we perform screening autoantibody testing with antinuclear antibody (ANA) by immunofluorescence, direct and indirect Coombs test (DCT/ICT), C3 level, HbA1c, thyroid function test (TFT) in all patients suspected of having immune dysregulation. The gene discussed is C3; the disease is Autoimmunity.