Serum levels of C3 were significantly higher in women with IBS (median, [147.8 mg/dL]; range, [83.40 mg/dL–213.2 mg/dL]) than in women of the HC group (median, [127.5 mg/dL]; range, [75.60 mg/dL–205 mg/dL]; p < 0.05). The gene discussed is C3; the disease is irritable bowel syndrome.