Why we need DAR

When a lesion occurs in the transcribed strand (TS) TCR removes it together with ~30 nucleotides then fills the gap using the non-transcribed strand (NTS) as a template.

If lesions were allowed to accumulate in the NTS over a lifetime, it is likely that there could be one within the gap created by TCR. This may lead to the introduction of a mutation when filling the gap.

DAR prevents this by maintaining the NTS free of lesions in spite of the lack in global genome repair.