The patients with arthritis were significantly older (median age: 3.8 vs. 2.8 years, p < 0.01) and had higher C-reactive protein (CRP) concentrations after acute treatment for KD (median: 1.08 vs. 0.50 mg/dL, p < 0.01) than those without arthritis, although there was no significant difference before treatment. The gene discussed is CRP; the disease is Arthritis.