期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1994
卷号：91
期号：8
页码：3166-3170
DOI：10.1073/pnas.91.8.3166
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Mutational processes of simple sequence repeats (SSRs) in complex genomes are poorly understood. We examined these processes by introducing a two-phase mutation model. In this model, most mutations are single-step changes, but infrequent large jumps in repeat number also occur. We used computer simulations to determine expected values of statistics that reflect frequency distributions of allele size for the two-phase model and two alternatives, the one-step and geometric models. The theoretical expectations for each model were tested by comparison with observed values for 10 SSR loci genotyped in the Sardinian population, whose genetic and demographic histories have been previously reconstructed. The two-phase model provided the best fit to the data for most of these loci in this population. In the analysis we assumed that the loci were neutral and that this population had undergone rapid population growth. Recent observations made for unstable trinucleotide repeats support our suggestion that frequent small changes and rare large changes in repeat number represent two distinct classes of mutation at SSR loci. We genotyped the same 10 loci in Egyptian and sub-Saharan African samples to assess the utility of SSRs for studying the divergence of populations and found that estimates of interpopulation distances from SSRs were similar to those derived from analysis of mitochondrial DNA.
