FAM72A antagonizes UNG2 to promote mutagenic repair during antibody maturation.

Activation-induced cytidine deaminase (AID) catalyses the deamination of deoxycytidines to deoxyuracils within immunoglobulin genes to induce somatic hypermutation and class-switch recombination. AID-generated deoxyuracils are recognized and processed by subverted base-excision and mismatch repair pathways that ensure a mutagenic outcome in B cells. However, why these DNA repair pathways do not accurately repair AID-induced lesions remains unknown.