The Control of Meiotic Recombination in the Human Genome.

Meiotic recombination plays a key role in reshuffling haplotypes in human populations and thus affects evolution profoundly. However, our understanding of recombination dynamics is largely limited to descriptions of variation in populations and families. Higher-resolution analysis (≤ 0.0001 cM) of de novo recombination events in human sperm DNA has revealed clustering into very narrow hotspots (1-2 kb) that generally coincide with abrupt breakdown of linkage disequilibrium. Recent findings have highlighted an unexpected molecular control of the distribution of meiotic double-strand breaks (DSBs) in mammals by a rapidly evolving gene in trans, PR-domain-containing 9 (PRDM9), and specific DNA sequence motifs in cis. In addition, the understanding of new regulators in DSB repair processes has allowed the delineation of recombination pathways that have two major outcomes, cross-overs and non-cross-overs, which have distinct mechanistic roles and consequences for genome evolution. Further molecular studies are needed to gain information about how hotspots originate, function, and evolve.