Minireview Hotspots of homologous recombination in the human genome: not comment all homologous sequences are equal James R Lupski Address: Departments of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. Current address (sabbatical until July 2005): Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK. E-mail:
[email protected] Published: 28 September 2004 reviews Genome Biology 2004, 5:242 The electronic version of this article is the complete one and can be found online at http://genomebiology.com/2004/5/10/242 © 2004 BioMed Central Ltd reports Abstract Homologous recombination between alleles or non-allelic paralogous sequences does not occur uniformly but is concentrated in ‘hotspots’ with high recombination rates. Recent studies of these hotspots show that they do not share common sequence motifs, but they do have other features in common. deposited research Homologous recombination is the process whereby two DNA this is not the case and have provided evidence for local sequence substrates that share a significant stretch of iden- ‘hotspots’ - short regions of the genome where strand tity are brought together, in an enzyme-catalyzed reaction, exchanges are more common than elsewhere. These obser- and undergo strand exchange to give a product that is a vations come from pedigree studies that examined the novel amalgamation of the two substrates. It occurs during parent-to-offspring transmission of alleles, linkage disequi- meiosis, leading to crossovers between alleles (allelic homol- librium (LD) studies and, more recently, direct DNA refereed research ogous recombination, AHR), and during repair of double- sequencing of the products of recombination using either strand breaks in DNA and other processes, leading to sperm (which represent a large number of recombination recombination between paralogous sequences (non-allelic products from a single meiosis) or junction fragments from homologous recombination, NAHR, also known as ectopic ectopic recombination (NAHR) [4,5].