Ancestry and phenotype predictions from touch DNA using massively parallel sequencing.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Standard short tandem repeat (STR) profiling requires known donor profiles and sufficient DNA quality/quantity.
• Trace DNA on touched items often lacks donor information, necessitating alternative genetic analysis methods.
• Massively parallel sequencing (MPS) offers enhanced sensitivity for detecting low-level DNA and improving analysis from challenging samples.

Purpose of the Study:

• To evaluate the efficacy of direct PCR coupled with MPS for generating forensic intelligence SNP data from latent DNA on touched objects.
• To assess the performance of the HIrisplex System (24 SNPs for hair/eye prediction) and the Precision ID Ancestry Panel (165 SNPs for biogeographic ancestry) using this combined approach.

Main Methods:

• Direct PCR amplification of DNA from touched samples.
• Library preparation using the Ion AmpliSeq Library Preparation Kit on the automated Ion Chef System.
• Sequencing on the Ion Torrent PGM platform.
• Analysis of SNP recovery, concordance with reference samples, and genotype reproducibility across different substrates and donors.

Main Results:

• Successful generation of single nucleotide polymorphism (SNP) profiles from trace DNA on various substrates (glass, fuse, zip-lock bag, wire).
• Demonstrated SNP recovery and genotype reproducibility from samples touched by multiple individuals.
• Concordance analysis confirmed the reliability of the generated SNP profiles compared to reference samples.

Conclusions:

• Direct PCR coupled with MPS is a viable method for obtaining informative genetic data from trace amounts of latent DNA.
• This technique provides valuable forensic intelligence, aiding investigations when traditional STR profiling is not feasible.
• The study highlights the potential of MPS-based SNP analysis for advancing forensic investigations involving touched items.