MLH1 and cancer: Cancers arise due to a germ-line mutation in one of the MMR genes; to the most part hMLH1 or hMSH2 (less frequently hMSH6 and rarely hPMS2) followed by a somatic second hit (chromatin alterations, such as histone modifications or mutations, rarely promoter methylations) that inactivates the relevant MMR gene [3, 4].