Microsatellites are repetitive sequences with unit length varying from 1–6 bp. During DNA replication, those repetitive sequences may expand or shrink due to strand slippage (Kawai et al., 1998). Those errors are often recognized and repaired by the DNA mismatch repair machinery, which includes genes such as MLH1 and MSH2 (Prolla et al., 1994). However, when mismatch repair enzymes are defective, replication errors will evade repair and will persist in somatic cells, as occurs in patients with hereditary non-polyposis colorectal cancer, also known as Lynch syndrome (Vasen et al., 1999).