Error-Prone Mismatch and Base Excision DNA Repair in Somatic Hypermutation

The large repertoire of antibodies that is achieved through V(D)J recombination does not create antibodies that have sufficient affinity and broad enough specificity to protect against all toxins and pathogenic organisms. To create such antibodies, B cells somatically hypermutate the antibody variable regions to increase affinity and the Ig switch regions to express those mutated variable regions with each of the isotypes through class switch recombination. This article focuses on how somatic mutations generated by activation-induced deaminase in the variable and switch regions are extended by noncanonical error-prone mismatch and base excision repair.