In order to evaluate the significance of anti-C1q antibodies in clinical settings, we analyzed the sensitivities and specificities of anti-C1q antibodies, anti-dsDNA antibodies, and levels of C3 and C4 alone or in a combination for the identification of patients with active SLE (Table 6) and LN (Table 7). The gene discussed is C3; the disease is systemic lupus erythematosus.