title: Significance of micro-geographical population structure in forensic cases: a bayesian exploration.
abstract: We studied the influence of population structure at the microgeographical level on the analysis of forensic cases. A total of nine autosomal STRs and seven Y-STRs were analyzed in the general mixed population and in two relatively isolated valleys of Cantabria, a region in Northern Spain. Statistically significant differences existed in the frequency distribution of four autosomal STRs, with an overall Fst value of 0.3%. A simulation of virtual trio cases revealed that it did not have a practical influence on the analysis of paternity disputes. Significant differences also existed in most Y-STRs, with an overall Fst value of 3%. Thus, using the general database instead of the specific valley database resulted in 5-fold or higher overestimation of the likelihood ratio of matching in up to 30% of cases. A bayesian analysis revealed that this had a significant impact on the estimation of the probability of identity in scenarios of low "a priori" odds of suspicion.
authors.affiliation: Unit of Legal Medicine, Faculty of Medicine, University of Cantabria, 39011, Santander, Spain. zarrabet@unican.es
authors.forename: María T
authors.initials: MT
authors.lastname: Zarrabeitia
authors.forename: José A
authors.initials: JA
authors.lastname: Riancho
authors.forename: María V
authors.initials: MV
authors.lastname: Lareu
authors.forename: Francisco
authors.initials: F
authors.lastname: Leyva-Cobián
authors.forename: Angel
authors.initials: A
authors.lastname: Carracedo
mesh_terms: D000483:Alleles; D001499:Bayes Theorem; D041322:Chromosomes, Human, Y; D004247:DNA / Q000097:blood / Q000235:genetics; D005554:Forensic Medicine / Q000379:methods*; D005787:Gene Frequency; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D010334:Paternity; D016133:Polymerase Chain Reaction; D020080:Tandem Repeat Sequences
chemical_list: D004247:DNA