Copy Number Varients
Mechanisms of change in gene copy number is a paper which appears in Nature Review Genetics. Its authors are P. J. Hastings, James R. Lupski, Susan M. Rosenberg and Grzegorz Ira. The paper takes note of a genetic phenomenon known as copy number varients (CNVs) which are duplications and deletions of chromosomal segments. They have been shown to account for variation among individual humans.
There was an interesting reference to cellular stress which it is thought "might induce repair of broken replication forks to switch from high-fidelity homologous recombination to non-homologous repair, thus promoting copy number change."1
1. Mechanisms of change in gene copy number; Nature Reviews Genetics 10, 551-564 (August 2009); P. J. Hastings, James R. Lupski, Susan M. Rosenberg and Grzegorz Ira.