Defective Mismatch Repair, Microsatellite Mutation Bias, and Variability in Clinical Cancer Phenotypes -- Shah et al. 70 (2): 431 -- Cancer Research

Abstract:
"Microsatellite instability is associated with 10% to 15% of colorectal, endometrial, OVARIAN, and gastric cancers, and has long been used as a diagnostic tool for hereditary nonpolyposis colorectal carcinoma–related cancers. Tumor-specific length alterations within microsatellites are generally accepted to be a consequence of strand slippage events during DNA replication, which are uncorrected due to a defective postreplication mismatch repair (MMR) system. Mutations arising within microsatellites associated with critical target genes are believed to play a causative role in the evolution of MMR-defective tumors. In this review, we summarize current evidence of mutational biases within microsatellites arising as a consequence of intrinsic DNA sequence effects as well as variation in MMR efficiency. Microsatellite mutational biases are generally not considered during clinical testing; however, we suggest that such biases may be clinically significant as a factor contributing to phenotypic variation among microsatellite instability–positive tumors."