Interpreting Mixture Profiles: Comparison Between Precision ID GlobalFiler™ NGS STR Panel v2 and Traditional Methods

Abstract

Forensic investigation for the identification of offenders, recognition of human remains, and verification of family relationships requires the analysis of particular types of highly informative DNA markers, which have high discriminatory power and are efficient for typing degraded samples. These markers, called STRs (Short Tandem Repeats), can be amplified by multiplex-PCR (Polymerase Chain Reaction) allowing attainment of a unique profile through which it is possible to distinguish one individual from another with a high statistical significance. The rapid and progressive evolution of analytical techniques and the advent of Next-Generation Sequencing (NGS) have completely revolutionized the DNA sequencing approach. This technology, widely used today in the diagnostic field, has the advantage of being able to process several samples in parallel, producing a huge volume of data in a short time. At this time, although default parameters of interpretation software are available, there is no general agreement on the interpretation rules of forensic data produced via NGS technology. Here we report a pilot study aimed for a comparison between NGS (Precision ID GlobalFiler™ NGS STR Panel v2, Thermo Fisher Scientific, Waltham, MA, USA) and traditional methods in their ability to identify major and minor contributors in DNA mixtures from saliva and urine samples. A quantity of six mixed samples were prepared for both saliva and urine samples from donors. A total of 12 mixtures were obtained in the ratios of 1:2; 1:4; 1:6; 1:8; 1:10; and 1:20 between minor and major contributors. Although the number of analyzed mixtures is limited, our results confirm that NGS technology offers a huge range of additional information on samples, but cannot ensure a higher sensitivity in respect to traditional methods. Finally, the Precision ID GlobalFiler™ NGS STR Panel v2 is a powerful method for kinship analyses and typing reference samples, but its use in biological evidence should be carefully considered on the basis of the characteristics of the evidence.

Evaluation of OpenArray™ as a Genotyping Method for Forensic DNA Phenotyping and Human Identification

“…To the best of our knowledge this is the first application of the OpenArray™ System in the forensic field. We designed a panel of 60 SNPs for phenotype estimation and personal identification [ 2 ]. SNPs for eye, hair, and skin color prediction were directly selected from the HIrisPlex-S system, while SNPs for human identification were selected from already validated subsets (the Precision ID Identity SNP Panel (Thermo Fisher Scientific, Waltham, MA, USA) and ForenSeq DNA Signature Prep Kit (Verogen Inc, San Diego, CA, USA) [ 16 , 17 , 18 , 19 ].…”

“…This evidence was from different tissues (10 from saliva, 2 from semen, 7 from blood, 2 from urine) and was attributed to 8 different subjects from different tissues [ 23 , 24 ]. All samples were marked with a specific internal code, as shown in Table 2 [ 2 ]. The forensic samples were loaded in the same plate twice with the purpose of verifying the reproducibility of genotyping assignation.…”

“…Short tandem repeats (STRs) are genetic variants widely used in forensic investigations for the identification of offenders and in cases concerning relationship testing [ 1 , 2 ]. However, the multiplexing capacity of STRs is relatively low because of the need for capillary electrophoresis and inability to accommodate large numbers of markers.…”

Macrophage-like THP-1 Cells Derived from High-Density Cell Culture Are Resistant to TRAIL-Induced Cell Death via Down-Regulation of Death-Receptors DR4 and DR5

“…Electrophoretic analysis was performed using a 3730/3130xl DNA Analyzer (Thermo Fisher Scientific, Waltham, MA, USA). After electrophoresis, the data were analyzed with Gene Mapper ® ID-X Software v1.5 [ 22 ] (Thermo Fisher Scientific, Waltham, MA, USA) to categorize peaks by size in relation to an internal standard allelic ladder.…”

Special Issue “Forensic Genetics and Genomics”

“…In the field of new technologies, the article by Ragazzo et al describes the application of NGS technology for DNA typing and for personal identification in the case of mixed biological evidence [5]. The results confirm that NGS technology offers a huge range of additional information on samples but cannot ensure a higher sensitivity with respect to traditional methods [7]. Thus, the Precision ID GlobalFiler™ NGS STR Panel v2 is confirmed as a powerful method for kinship analyses and typing reference samples, but its use in analyzing biological evidence should be carefully considered on the basis of the characteristics of the evidence (DNA amount and degradation) [7].…”