Zur Evolution von Short Tandem Repeats

The stepwise mutation model (SMM) is a simple, widely used model to describe the evolutionary behaviour of microsatellites. We apply a Markov chain description of the SMM and derive the marginal and joint properties of this process. In addition to the standard SMM, we also consider the normalised allele process. In contrast to the standard process, the normalised process converges to a stationary distribution. We show that the marginal stationary distribution is unimodal. The standard and normalised processes capture the global and the local behaviour of the SMM, respectively. (ii) Jochens, Caliebe, Rösler und Krawczak (2011) Empirical Evaluation Reveals Best Fit of a Logistic Mutation Model for Human Y-chromosomal Microsatellites. Genetics 189:4, 1403–1411. Abstract: The rate of microsatellite mutation is dependent upon both the allele length and the repeat motif, but the exact nature of this relationship is still unknown. We analysed data on the inheritance of human Y-chromosomal microsatellites in father-son duos, taken from 24 published reports and comprising 15,285 directly observable meioses. At the six microsatellites analysed (DYS19, DYS389 I, DYS390, DYS391, DYS392 and DYS393), a total of 162 mutations were observed. For each locus, we employed a maximum likelihood approach to evaluate one of several single-step mutation models on the basis of the data. For five of the six loci considered, a novel logistic mutation model was found to provide the best fit according to Akaike’s Information Criterion. This implies that the mutation probability at the loci increases (non-linearly) with allele length at a rate that differs between upward and downward mutations. For DYS392, the best fit was provided by a The rate of microsatellite mutation is dependent upon both the allele length and the repeat motif, but the exact nature of this relationship is still unknown. We analysed data on the inheritance of human Y-chromosomal microsatellites in father-son duos, taken from 24 published reports and comprising 15,285 directly observable meioses. At the six microsatellites analysed (DYS19, DYS389 I, DYS390, DYS391, DYS392 and DYS393), a total of 162 mutations were observed. For each locus, we employed a maximum likelihood approach to evaluate one of several single-step mutation models on the basis of the data. For five of the six loci considered, a novel logistic mutation model was found to provide the best fit according to Akaike’s Information Criterion. This implies that the mutation probability at the loci increases (non-linearly) with allele length at a rate that differs between upward and downward mutations. For DYS392, the best fit was provided by a geteilte Erstautorenschaft