Most gene structure is stable, however, genes can be rearranged, and this can have an impact on regulation.

The movement of a segment of DNA from one place to another on a chromosome can act as a switch to turn a gene on or off at different stages during development.

A rearrangement which brings the gene under the control of a strong promotor activates expression, while one which places the gene into regulatory or protein-coding sequences can interrupt or prevent expression.

Similar to alternative mRNA splicing, gene rearrangement can result in the production of multiple protein products from a single gene sequence.  An example of this is the enormous number of antibody types which can arise from only a small number of immunoglobulin gene sequences.