Recombination events that activate, diversify, and delete immunoglobulin genes

Immunoglobulin kappa light-chain diversity arises, in large part, from an array of germ-line V-region genes that undergo somatic recombination with one of four active J-region segments. The diversity provided by this combinational system is increased by a recombination mechanism that allows variation of crossover points so as to generate additional diversity at a critical region of the light chain. The elaborate mechanism for generating diversity is accompanied not only by considerable waste, in terms of unused V and J regions in a given cell, but also by a range of aberrant recombinants that fail to produce active immunoglobulin genes.