Meiotic recombination hot spots and cold spots

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Abstract
Eukaryotic chromosomes have regions of high (hot spots)and low (cold spots) meiotic recombination. These distortions of the genetic maps complicate gene identification by positional cloning strategies. Meiotic recombination in yeast (and probably other eukaryotes) is initiated by meiosis-specific double-stranded DNA breaks (DSBs). In yeast, DSBs occur preferentially in regions of 'open' chromatin, and some hot spots require the binding of transcription factors, but not high levels of transcription. Hot spots are clustered in high G + C domains that often contain more than one preferred site for DSB formation. Telomeric and centromeric regions often have low levels of meiotic exchange. In humans, regions of elevated recombination have been observed on several chromosomes. The location and strength of these 'hot' regions is often different in males and females. Several human hot spots have been mapped to kilobase resolution using linkage disequilibrium and sperm typing. Covalent modification of histones affects gene expression, DNA replication and chromosome condensation. Various experimental observations indicate that these modifications might also influence the distribution of meiotic recombination events.