A 60-year-old African American woman was diagnosed with systematic lupus erythematosus (SLE) in December 1999, characterized by malar rash, arthritis, proteinuria, leukopenia, positive ANA (1:640, homogenous and speckled pattern), anti-Smith, anti-RNP, and low C3. The gene discussed is C3; the disease is Decreased total leukocyte count.