"Biological identikit": development of a SNPs-panel for the analysis of forensic DNA phenotyping and ancestry

The need to identify victims of mass disasters and perpetrators of crimes is fundamental for humanitarian, ethical and legal reasons. Individuals, whose genetic profiles are not yet known to investigators, cannot be identified by standard forensic DNA analysis. To date, technological progress allows for the analysis of Forensic DNA Phenotyping (FDP) which provides for the definition of Externally Visible Features (EVCs); and the analysis of the biogeographical ancestry (BGA), which allows to define the ancestral origin. The aim of this study was to evaluate the potential of a new panel of about 900 SNPs in predicting phenotypic traits and biogeographical origin. Recent biological material was analysed and subsequently the analysis was extended to include evidence found at the crime scene or extracted DNA, both preserved for long periods of time. The goal was to create a "biological identikit", useful for determining the phenotypic characteristics of unknown corpses and directing investigators to alleged victims or relatives or in a crime to narrow the circle of suspects. The panel consists of 41 SNPs for phenotyping and 850 SNPs for ancestry. It was tested on 8 recent samples and 26 samples extracted and stored for a long time. All the 891 SNPs were successfully incorporated into a single two-step multiplex PCR reaction using the IonAmpliSeq ™ Library Plus and applied for massive parallel sequencing with the Ion S5 platform using up to 0.05 ng / µl of DNA. The analysis of the results was carried out with an in-house predictive algorithm and by consulting 20 databases containing population frequencies. By comparing the results obtained with identikit or video-photographic surveys, it was possible to predict the phenotype and ancestry with an accuracy more than 90%. Although these new markers are unable to identify an individual, they can be a valuable investigative tool useful for personal identification.