Open source software EuroForMix can be used to analyse complex SNP mixtures

Area of Science:

• Forensic genetics
• Molecular biology
• Statistical genetics

Background:

• Mixture analysis is crucial in forensic DNA profiling.
• Previous methods using qualitative software had limitations with complex mixtures.
• Massively parallel sequencing (MPS) generates rich data for analysis.

Purpose of the Study:

• To evaluate a quantitative approach for DNA mixture analysis using MPS data.
• To compare the performance of quantitative (EuroForMix) and qualitative (LRmix) software.
• To assess the impact of sequence read coverage on the strength of evidence.

Main Methods:

• Analysis of two- and three-person DNA mixtures using the HID-Ion AmpliSeq™ Identity Panel v2.2.
• Utilized 134 autosomal single nucleotide polymorphisms (SNPs).
• Employed likelihood ratio (LR) calculations with EuroForMix, incorporating sequence read coverage.

Main Results:

• Quantitative analysis with EuroForMix, using sequence read coverage, significantly improved mixture analysis compared to qualitative LRmix, especially for three or more contributors.
• The strength of evidence (LR) increased with the mixture proportion (Mx) and was relatively insensitive to the number of contributors.
• Faster analysis times were achieved, with calculations for three contributors taking only six seconds.

Conclusions:

• Incorporating sequence read coverage into quantitative models provides a significant advantage over qualitative methods for DNA mixture interpretation.
• The quantitative approach enhances the discrimination power in forensic mixture analysis.
• This method offers a fast and efficient tool for complex forensic casework.