Of note, a combination of anti-C1q antibodies and anti-dsDNA antibodies or serum levels of C3 and C4 could significantly increase specificities but decrease the sensitivities in identification of patients with active SLE and LN in comparison with these serological markers alone (p < 0.05) (Tables 6 and 7). The gene discussed is C4A; the disease is systemic lupus erythematosus.