Figure 2.

Schematic illustration of how the stability of microsatellite regions can be affected by the presence of a dysfunctional MMR system. (a) DNA polymerase performs the replication of a microsatellite sequence composed of 8 repeats of cytosine/adenine (CA). (b) Due to the slippage of DNA polymerase during replication, a CA repeat is wrongly incorporated. (c) If the MMR system is intact, the replication error is corrected and the right number of repeats is maintained. (d) If the MMR system is dysfunctional, the additional CA repeat will not be eliminated, leading to instability in the length of the microsatellite region.