H. pylori -induced methylation of the CpG-island-containing and -lacking genes according to the distance to the nearest retroelements and the transcription activity. A total of 14 transitional-CpG sites were grouped into eight CpG-island genes (CDH1, ARRDC4, PPARG, CDKN2A, TRAPPC2L, DUSP6, MLH1 and RUNX3) and six genes lacking CpG-islands (PGA5, PGC, TFF1, TFF2, MSLN and KRT6A). The gene-retroelement distance was estimated between the transcriptional start sites and the nearest Alu, L1 or LTR retroelements. The H. pylori-induced methylation rate was represented by the H. pylori-positive-to-negative ratio of the overmethylation rate. The overmethylation rate was calculated according to the relative proportion of overmethylated cases to the total sum of the over- and under-methylated cases. The transcriptional activity of each gene was shown with the number of expressed transcripts .