Here we use the presence of a colorectal cancer (CRC) risk variant (rs1800734) within the MLH1 promoter to investigate the poorly understood mechanisms of MLH1 promoter methylation and loss of expression.
We previously demonstrated that SNPs (rs1800734, rs749072, and rs13098279) in the MLH1 gene region are associated with MLH1 promoter island methylation, loss of MLH1 protein expression, and microsatellite instability (MSI) in colorectal cancer (CRC) patients.
When candidate SNPs were examined, our data did not support most of the previously reported associations with CRC susceptibility, an exception being an effect of the MLH1 promoter SNP -93G>A (rs1800734).
A single nucleotide polymorphism (SNP) in the CpG island of <i>MLH1</i> (<i>MLH1</i>-93G>A or rs1800734) is associated with CpG island hypermethylation and decreased <i>MLH1</i> expression in CRC tumours.