Somatic
Hypermutation
Theory
This theory proposes that point mutations in the V regions result in the formation of many new V regions from the limited number of V regions inherited by an individual. A very large number of mutations would be necessary to produce the required antibody diversity. It has been suggested that .the DNA repair mechanism bas been designed to commit a high frequency of mistakes.
According to this scheme, one of the DNA strands of the V genes is cleaved by a specific nuclease and trimmed by an exonuclease. A DNA repair enzyme designed to commit replication mistakes then fills in the gaps, thus producing new amino acid sequences for the V region
