Development and application of Y-chromosomal markers in Forensic Genetics

The characterization of molecular variants at Y-STR markers (deletions, duplications or mutations) is fundamental for many aspects of forensic genetics, including male identification, genealogy and evolutionary studies. While the first two types (deletions and duplications) possess much lower mutation rates, differently, repeats units differences are dependent on intrinsic properties of each Y-STR (e.g., complexity of the locus), occur with much higher frequencies and may show population-specificity. Therefore, assessment of reliable locus-specific mutation rates is needed for a careful choice of loci suitable for forensic casework, minimizing error rates in kinship analysis and sample identification while maximizing the discriminatory power. At the same time, the characterization of anomalous patterns at Y-STR loci is of primary importance for the correct interpretation of genetic profiles, and such events may suggest the existence of hidden complex rearrangements shaping the Y-chromosomal structure. Owing to the intrinsic nature of the Y-chromosome, these structural variations are generally passed along the generations without major modifications and may be potentially associated with specific Y-haplogroups. By bringing all these aspects together, a more accurate and complete overview of Y-chromosomal variation could be achieved, taking into account the population genetic background and history. This, in turn, may allow the construction of highly informative haplotypes, essential for a correct interpretation of Y-chromosomal profiles in forensic genetics.