Hypermutation

(somatic hypermutation, SHM); endogenous mechanism allowing fast adaptation of the immune system for the efficient recognition and defense against foreign elements (such as viruses and bacteria)

Description
SHM introduces variation into the paratopes (the recognition elements) of immunoglobulins, thus allowing the selection of lymphocytes producing better matched paratopes and hence an optimisation of antigen recognition by the body. SHM is somatic, i.e. it is not passed on through the germline, and affects the variable regions of immunoglobulins by a diversity of mechanisms. See memory lymphocyte, mutation