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Heterogeneous mutation processes in human microsatellite DNA sequences.
1Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden. Hans.Ellegren@evolution.uu.se
Nature Genetics
|March 31, 2000
Summary
Microsatellite DNA evolution is driven by mutation biases. Long alleles tend to shorten, preventing infinite growth, and human mutations show a male bias.
Area of Science:
- Genomics
- Molecular Evolution
- Population Genetics
Background:
- Microsatellite polymorphisms are crucial genetic analysis tools.
- The evolutionary mechanisms of microsatellite DNA, a highly abundant repetitive sequence in eukaryotic genomes, are not fully understood.
Purpose of the Study:
- To investigate the evolutionary processes of microsatellite DNA.
- To identify mutation biases influencing microsatellite repeat evolution.
Main Methods:
- Analysis of spontaneous human germline microsatellite mutations.
- Examination of mutation rates in relation to allele length and allele span.
- Comparison of expansion and contraction biases between dinucleotide and tetranucleotide repeats.
Main Results:
- Within-locus mutation rate increases with allele length but is independent of allele span.
- Longer microsatellite alleles exhibit a mutational bias towards shorter lengths.
- Dinucleotide repeats show a bias towards expansion, unlike tetranucleotide repeats.
- A male-biased mutation rate was observed, with a paternal transmission excess (4.9:1 male-to-female ratio).
Conclusions:
- Mutation biases significantly shape microsatellite repeat evolution.
- Allele length-dependent mutation and a bias towards shortening prevent uncontrolled microsatellite growth.
- Repeat type influences expansion/contraction dynamics.
- The human genome exhibits a male-biased mutation rate.