spontaneous or enzymatic deamination of 5-methylcytosine
Polymerase epsilon exonuclease domain mutations
Concurrent polymerase epsilon mutation and defective DNA mismatch repair
Possibly damage by reactive oxygen species
Concurrent POLD1 mutations and defective DNA mismatch repair
deficiency in base excision repair due to inactivating mutations in NTHL1
Prior chemotherapy treatment with platinum drugs
Prior treatment with azathioprine to induce immunosuppression
Prior chemotherapy treatment with platinum drugs.
Defective base excision repair due to biallelic germline or somatic MUTYH mutations
Activity of activation-induced cytidine deaminase (AID)
Indirect effects of activation-induced cytidine deaminase (AID)