MSI may be caused by sporadic events (e.g. epigenetic silencing of the MLH1 gene) or by constitutive mutations in one of the MMR genes—the most common of which are MLH1, MSH2, MSH6 and PMS2—resulting in the most common hereditary cancer syndrome (Lynch Syndrome) [20]. Here, MLH1 is linked to Inherited cancer-predisposing syndrome.