engleski

Analysis of three-locus STR haplotypes as a tool to study inbreeding effects

Today it is generally accepted that short tandem repeat (STR) sequences can provide sufficient information to determine identity or paternity in most forensic cases. Elaborate statistical methods have been developed to quantify the significance of genetic matches, but the calculated numbers may not be valid in all situations and have to be used with caution. As a part of the process of identification of war victims in Croatia we have randomly matched hundreds of thousands of genotypes and observed unexpectedly high number of statistically improbable matches between unrelated people. We speculated that this might be a consequence of higher than expected frequency of specific combinations of STR alleles because of local inbreeding. To assess this hypothesis we have developed a novel method that analyses incidence of all possible three-locus haplotype combinations (mini-haplotypes) in a population. After calculating frequencies for all possible mini-haplotypes we confirmed our hypothesis that some combinations are much more frequent than expected. Different combinations were found to be most frequent in Croatian and Hungarian populations supporting the hypothesis that these aberrations from expected values might be population-specific. Probabilities of complete 9-loci haplotypes calculated by combining frequencies of three-locus haplotypes can be significantly different from probabilities calculated using individual alleles, suggesting that currently used statistical methods might not be accurate in genotypes that contain these over-abundant mini-haplotypes.

genotyping; STR; human identity; inbreeding

nije evidentirano