Bracketing off populations does not advance ethical reflection on EVCs: A reply to Kayser and Schneider

In a recent contribution to this journal, Kayser and Schneider reviewed the relevance of external visible characteristics (EVCs) for criminal investigation [1]. Their aim was to broaden the debate about the scientific, legal, and ethical dimensions of the use of EVCs for criminal investigation, which will help to achieve a firm legal basis for the application of EVCs eventually. While we applaud Kayser's and Schneider's overall very thoughtful and nuanced discussion of this topic, we were surprised to read that they suggest that a discussion of ‘the challenges of using problematic definitions of populations […] has to be kept separate from using EVCs’ (p. 158). In contrast to these authors, we contend that questions about defining populations – both at the level of scientific research, and the application of EVCs in criminal investigation – lie at the core of most social, ethical, and legal issues raised by the translation of EVCs into forensic and police practice

An efficient clustering algorithm for partitioning Y-short tandem repeats data

<p>Abstract</p> <p>Background</p> <p>Y-Short Tandem Repeats (Y-STR) data consist of many similar and almost similar objects. This characteristic of Y-STR data causes two problems with partitioning: non-unique centroids and local minima problems. As a result, the existing partitioning algorithms produce poor clustering results.</p> <p>Results</p> <p>Our new algorithm, called <it>k</it>-Approximate Modal Haplotypes (<it>k</it>-AMH), obtains the highest clustering accuracy scores for five out of six datasets, and produces an equal performance for the remaining dataset. Furthermore, clustering accuracy scores of 100% are achieved for two of the datasets. The <it>k</it>-AMH algorithm records the highest mean accuracy score of 0.93 overall, compared to that of other algorithms: <it>k</it>-Population (0.91), <it>k</it>-Modes-RVF (0.81), New Fuzzy <it>k</it>-Modes (0.80), <it>k</it>-Modes (0.76), <it>k</it>-Modes-Hybrid 1 (0.76), <it>k</it>-Modes-Hybrid 2 (0.75), Fuzzy <it>k</it>-Modes (0.74), and <it>k</it>-Modes-UAVM (0.70).</p> <p>Conclusions</p> <p>The partitioning performance of the <it>k</it>-AMH algorithm for Y-STR data is superior to that of other algorithms, owing to its ability to solve the non-unique centroids and local minima problems. Our algorithm is also efficient in terms of time complexity, which is recorded as <it>O</it>(<it>km</it>(<it>n-k</it>)) and considered to be linear.</p

Mutability of Y-Chromosomal Microsatellites: Rates, Characteristics, Molecular Bases, and Forensic Implications

Nonrecombining Y-chromosomal microsatellites (Y-STRs) are widely used to infer population histories, discover genealogical relationships, and identify males for criminal justice purposes. Although a key requirement for their application is reliable mutability knowledge, empirical data are only available for a small number of Y-STRs thus far. To rectify this, we analyzed a large number of 186 Y-STR markers in nearly 2000 DNA-confirmed father-son pairs, covering an overall number of 352,999 meiotic transfers. Following confirmation by DNA sequence analysis, the retrieved mutation data were modeled via a Bayesian approach, resulting in mutation rates from 3.78 × 10−4 (95% credible interval [CI], 1.38 × 10−5 − 2.02 × 10−3) to 7.44 × 10−2 (95% CI, 6.51 × 10−2 − 9.09 × 10−2) per marker per generation. With the 924 mutations at 120 Y-STR markers, a nonsignificant excess of repeat losses versus gains (1.16:1), as well as a strong and significant excess of single-repeat versus multirepeat changes (25.23:1), was observed. Although the total repeat number influenced Y-STR locus mutability most strongly, repeat complexity, the length in base pairs of the repeated motif, and the father's age also contributed to Y-STR mutability. To exemplify how to practically utilize this knowledge, we analyzed the 13 most mutable Y-STRs in an independent sample set and empirically proved their suitability for distinguishing close and distantly related males. This finding is expected to revolutionize Y-chromosomal applications in forensic biology, from previous male lineage differentiation toward future male individual identification