Linking class-switch recombination with somatic hypermutation

The discovery of activation-induced cytidine deaminase (AID) has revealed that there is a molecular link between two apparently different genetic alteration events — class-switch recombination and somatic hypermutation — which take place in the immunoglobulin loci of antigen-stimulated B lymphocytes. These findings led us to propose that the recognition and cleavage steps of the two events may be mediated by a similar or the same molecule. Because AID seems to be an RNA-editing enzyme, these results also suggest that the complexity of mammalian genetic information may be enriched by an interplay between RNA editing and DNA modification.