Rekombinationshotspots

Rekombinationshotspots, or recombination hotspots, are short regions in a genome where meiotic recombination occurs more frequently than in surrounding DNA. During meiosis, the formation of double-strand breaks initiates genetic exchange between homologous chromosomes, producing crossovers and gene conversions. Hotspots are typically defined by elevated recombination activity within a few hundred to a few thousand base pairs.

The localization of Rekombinationshotspots is influenced by specific molecular determinants. In many vertebrates, the PRDM9 protein binds particular DNA motifs and helps recruit the machinery that forms double-strand breaks, guiding recombination to those motifs. The binding motifs and the PRDM9 zinc-finger array evolve rapidly, causing hotspot locations to shift over evolutionary time. In species with no functional PRDM9, hotspots tend to cluster near promoter regions, CpG islands, or other regions of open chromatin, reflecting a more chromatin-guided pattern of recombination.

Hotspot distribution varies among species and populations, contributing to differences in genetic diversity and linkage disequilibrium. The rapid evolution of hotspot motifs and biased gene conversion can lead to hotspot turnover, meaning that the same genomic region may be a hotspot in one lineage but not in another. This turnover has implications for genetic mapping and the interpretation of association studies.

Applications and significance include shaping patterns of genetic variation, influencing genome evolution, and affecting the resolution of disease gene mapping. Researchers identify hotspots through approaches such as mapping crossover events in pedigrees, sequencing offspring, and profiling double-strand-break marks or PRDM9 binding sites.