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Author Topic:   How Many Mutations Does Each Human Have?
Wounded King
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Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 13 of 20 (348453)
09-12-2006 2:56 PM
Reply to: Message 11 by NosyNed
09-12-2006 1:08 PM


Re: Determing the number
Direct estimates of human per nucleotide mutation rates at 20 loci causing mendelian diseases
Kondrashov AS.
Hum Mutat. 2003 Jan;21(1):12-27
I estimate per nucleotide rates of spontaneous mutations of different kinds in humans directly from the data on per locus mutation rates and on sequences of de novo nonsense nucleotide substitutions, deletions, insertions, and complex events at eight loci causing autosomal dominant diseases and 12 loci causing X-linked diseases. The results are in good agreement with indirect estimates, obtained by comparison of orthologous human and chimpanzee pseudogenes. The average direct estimate of the combined rate of all mutations is 1.8x10(-8) per nucleotide per generation, and the coefficient of variation of this rate across the 20 loci is 0.53. Single nucleotide substitutions are approximately 25 times more common than all other mutations, deletions are approximately three times more common than insertions, complex mutations are very rare, and CpG context increases substitution rates by an order of magnitude. There is only a moderate tendency for loci with high per locus mutation rates to also have higher per nucleotide substitution rates, and per nucleotide rates of deletions and insertions are statistically independent on the per locus mutation rate. Rates of different kinds of mutations are strongly correlated across loci. Mutational hot spots with per nucleotide rates above 5x10(-7) make only a minor contribution to human mutation. In the next decade, direct measurements will produce a rather precise, quantitative description of human spontaneous mutation at the DNA level.
While this paper doesn't do any direct measurement of mutational rates itself it uses a number of directly observed mutational rate studies on specific genes to estimate average rates for mutation. Their rate works out to around ~100 'new' mutations per diploid human genome per generation, while some of these 'new' mutations may have been seen before they occur de novo in these cases.
TTFN,
WK

This message is a reply to:
 Message 11 by NosyNed, posted 09-12-2006 1:08 PM NosyNed has replied

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 20 of 20 (522438)
09-03-2009 11:55 AM


Confirmation of previous estimates (also Thread Necromancy)
A paper is due to be published shortly in the journal Current Biology which compares the Y-chromosomes of two men from the same family but several generations apart (Xue et al., 2009).
They arrive at results showing similar levels of mutation to those discussed previously. They identify 4 new mutations to have arisen in vivo in the intervening 13 generations and from that derive a mutation rate of 3x10-8 mutations/nucleotide/generation. This gives roughly ~150 new single nucleotide mutations/ diploid genome/ generation, more than Kondrashov's estimate but within a very similar ball park.
TTFN,
WK

  
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