The mean methylation level was 18.3 % [95 % confidence interval (CI), 14.5–22.2 %] among gastric cancer tissues that displayed over 1.0 % methylation in the DCC promoter and 4.9 % (95 % CI, 3.3–6.5 %) in the corresponding normal gastric mucosa specimens that displayed over 1.0 % methylation (P < 0.0001, Wilcoxon/Kruskal–Wallis test; Fig. 1c–d). The gene discussed is DCC; the disease is gastric cancer.