Germline promoter hypermethylation of tumor suppressor genes in gastric cancer

Figure 1 Germline MLH1 promoter hypermethylation analysis in a gastric cancer patient cohort. A: Map of the CpG island structure in the MLH1 promoter. The sequence is numbered relative to the translation start site for human MLH1 (bolded “ATG” ). Characters in blue indicate the primer binding sites for bisulfite sequencing. Individual CpG sites in the sequence are numbered consecutively; B: Bisulfite sequencing of MLH1 promoter sequences. G46, DNA isolated from the blood of case G46 showing a mixture of C and T at the 6th to 20th CpG sites attributable to partial modification of the DNA due to partial methylation; Methylated DNA control, CpGenome Universal Methylated DNA in which MLH1 is completely methylated showing a high C content at all CpGs attributable to reduced modification because of complete methylation of the DNA; Unmethylated DNA control, CpGenome Universal Unmethylated DNA showing T bases at all CpGs except the 9th and 10th CpG sites due to almost complete modification of the DNA. The 9th and 10th CpG sites show a high number of Cs in G46, but also in the unmethylated control, suggesting that these sites are uninformative in relation to gastric cancer.