Therefore, the other characteristics are not reported.SLE = systemic lupus erythematosus, MAS = macrophage activation syndrome, WBC = white blood cell count, Hb = hemoglobin, LDH = lactate dehydrogenase, AST = aspartate aminotransferase, ALT = alanine aminotransferase, CRP = C-reactive protein, ESR = erythrocyte sedimentation rate, C3 = complement component 3, C4 = complement component 4, ANA = antinuclear antibody, anti-dsDNA = anti-double-stranded DNA, CNS = central nervous system. The gene discussed is C4A; the disease is macrophage activation syndrome.