After multivariable adjustment, IFN-α—but not IFN-γ—was significantly and positively associated with acute-phase reactants (C-reactive protein and interleukin-6), disease activity indices (SLEDAI-2K, beta coefficient: 0.20 [95% confidence interval 0.09, 0.32] log pg/ml, p < 0.001 and SLE-DAS, beta coefficient: 0.15 [95% confidence interval 0.05, 0.25] log pg/ml, p = 0.003) and the presence of antinuclear antibodies. This evidence concerns the gene IFNA1 and systemic lupus erythematosus.