Fig. 1

Scattergrams of DNA methylation levels obtained by the Infinium assay for representative CpG sites showing area under the curve values of more than 0.95 in receiver operating characteristic curve analysis for discrimination between non-cancerous liver tissue showing non-alcoholic steatohepatitis (NASH) derived from partial hepatectomy specimens from patients with hepatocellular carcinoma (HCC) (NASH-W) (n = 22, red) and normal liver tissue (NLT) samples (n = 36, black). The Infinium probe ID and gene symbol are shown at the top of each panel. N/A, not annotated (designed in the intergenic regions). DNA methylation alteration at the NASH stage compared to NLT was inherited by or strengthened in NASH-related HCC (T) samples (n = 22, green). Using each CpG site and its cutoff value described in Additional file 1: Table S3, NASH-W samples were discriminated from NLT samples with sufficient sensitivity and specificity (90.9–100%). ^aP values by Welch’s t test. ^bP values by Jonckheere–Terpstra trend test. ^cSensitivity was defined as the ratio of the number of tissue samples diagnosed as NASH-W based on the criteria described in Additional file 1: Table S3 relative to the exact number of NASH-W samples, and specificity was defined as the ratio of the number of tissue samples not diagnosed as NASH-W based on the criteria relative to the exact number of NLT samples