Genome-wide DNA methylation profiling of gastric tumors and matched gastric non-malignant samples. The Illumina HumanMethylation27 BeadChip was used to obtain DNA methylation profiles across 27,578 CpGs in 203 gastric tumors and 94 matched non-malignant gastric samples. Overall design: Bisulphite-converted DNA from the 203 gastric tumors and 94 matched gastric non-malignant samples was hybridized to the Illumina HumanMethylation27 BeadChip.