Gene mapping – first lecture

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Recombination distribution

• Recombination deserts - >5Mb, <0.3 cM per Mb

• Recombination “jungle” - >3cM per Mb.

Example: X pseudo-autosomal region. An obligatory one crossover in each bivalent.

Recombination distribution

• The chromosomes consist of conserved blocks, typically 20-50kb long, separated by recombination hot spots.

• ~95% of all recombination occurs in these 1-2kb hotspots.

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Two point mapping

• How can we work out the recombination fraction?

• What statistical test should we use to see if recombination fraction I is significantly different from 0.5, the value expected on the null hypothesis of no linkage?

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