Her medical history showed that 1 month prior to admission she had photosensitivity, rash, and arthralgia, with positive antinuclear antibody test, positive anti-double-stranded DNA test, positive anti-ribosomal protein P, and complement C4 (7.4 mg/dL); she was diagnosed as having systemic lupus erythematosus and started therapy. This evidence concerns the gene C4A and systemic lupus erythematosus.