The results clearly demonstrated that bio-naïve Elderly-EO IBD patients exhibit a decreased response to anti-TNF treatment compared with Non-elderly IBD patients, and that long-term efficacy of anti-TNF treatment for bio-naïve Elderly-EO could be expected if the IBD-type was CD, the disease duration was less than 1 year, and the patients were without concomitant corticosteroid treatment at the start of anti-TNF treatment. The gene discussed is TNF; the disease is inflammatory bowel disease.