Abstract：
Roughly 3% of the human genome consists of microsatellites or tracts of short tandem repeats (STRs). These STRs are often unstable, undergoing high-frequency expansions (increases) or contractions (decreases) in the number of repeat units. Some microsatellite instability (MSI) is seen at multiple STRs within a single cell and is associated with certain types of cancer. A second form of MSI is characterised by expansion of a single gene-specific STR and such expansions are responsible for a group of 40+ human genetic disorders known as the repeat expansion diseases (REDs). While the mismatch repair (MMR) pathway prevents genome-wide MSI, emerging evidence suggests that some MMR factors are directly involved in generating expansions in the REDs. Thus, MMR suppresses some forms of expansion while some MMR factors promote expansion in other contexts. This review will cover what is known about the paradoxical effect of MMR on microsatellite expansion in mammalian cells.
摘要：
大约3％的人类基因组由微卫星或短串联重复序列（STR）组成。这些可疑交易报告往往不稳定，重复单元数经历高频扩展（增加）或收缩（减少）。在单个细胞内的多个STR处看到一些微卫星不稳定性(MSI),并且与某些类型的癌症相关。MSI的第二种形式的特征在于单基因特异性STR的扩增,并且这种扩增负责一组40+人遗传疾病,称为重复扩增疾病(REDs)。虽然错配修复（MMR）途径阻止全基因组MSI，新出现的证据表明，一些MMR因素直接参与了REDs的扩张。因此，MMR抑制某些形式的扩张，而某些MMR因素在其他情况下促进扩张。这篇综述将涵盖已知的MMR对哺乳动物细胞中微卫星扩增的矛盾作用。
