Development and validation of a new multiplex for upgrading Y-STRs population databases from 12 to 23 markers and its forensic casework application.

Y chromosomal short tandem repeats (Y-STRs) are used in forensic investigations as a useful complementary tool to autosomal markers. The ongoing development of new kits with an increasing number of markers makes it necessary to update populations typed in the Y-STR Haplotype Reference Database to reach at least 23 Y-STRs. A novel Y-STR multiplex panel was developed to offer a cost-efficient alternative to update Y-STR haplotypes from 12 to 23 loci. This panel includes the eleven markers, DYS448, DYS456, DYS458, DYS635, Y-GATA H4, DYS576, DYS481, DYS549, DYS533, DYS570 and DYS643, as well as DYS385a/b for traceability purpose. Developmental validation of this panel was conducted following the recommendations of the Scientific Working Group on DNA Analysis Methods (SWGDAM), showing high sensitivity, tolerance to common inhibitors as well as high species specificity. It was efficient for degraded DNA samples and for detection of male mixtures. When applying it for extending the current data of the Ibiza population, both the discrimination capacity and the haplotype diversity increased from 0.5952 to 0.9048 and from 0.9808 to 0.9977, respectively. Together, the study demonstrates the suitability of this panel in forensic casework.

Intrinsic and extrinsic factors that may influence DNA preservation in skeletal remains: A review.

The identification of skeletal human remains, severely compromised by putrefaction, or highly deteriorated, is important for legal and humanitarian reasons. There are different tools that can help in the identification process such as anthropological and genetic studies. The success observed during the last decade in genetic analysis of skeletal remains has been possible especially due to the refinements of DNA extraction and posterior analysis techniques. However, despite these progresses, many challenges keep influencing the results of such analysis, mainly the limited amount and the degradation of the DNA recovered from badly preserved samples. By now, there is still no wide-range knowledge about post-mortem kinetics of DNA degradation. Therefore, taphonomy studies can play a key role in the reconstruction of post-mortem transformations that skeletal remains, and consequently DNA, have undergone. Thus, the goal of the present review focuses on the assessment of the literature regarding the possible effect of intrinsic (characteristics of the bone) and extrinsic (environmental) factors on the state of preservation of skeletal remains recovered in a terrestrial environment and their genetic material. The establishment of useful indicators describing the state of the remains is a key factor in order to determine their suitability for posterior biomolecular analysis.