Figure 4.
A working model for a higher mutation rate in hypermethylated regions. Deaminated cytosine (U:G mismatch) is repaired by base excision repair (BER), but deaminated 5-methyl-cytosine (T:G mismatch) is corrected by more complicated repair pathways. An alternative mismatch repair system (MMR) might involve low-fidelity DNA polymerase, resulting in the error-prone synthesis of erased gaps.
