Estimating Individual Contributions to Complex DNA SNP Mixtures.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Short tandem repeats (STRs) are traditionally used for forensic DNA analysis.
• High-throughput sequencing (HTS) of single nucleotide polymorphisms (SNPs) presents a complementary or alternative approach for complex forensic samples.
• Existing methods for estimating DNA contributions in mixtures rely on capillary electrophoresis or HTS allele counts.

Purpose of the Study:

• To introduce and evaluate three novel methods for estimating individual DNA contributions in forensic mixtures using HTS/massively parallel sequencing (MPS) SNP panels.
• To compare the accuracy of mean, median, and slope-intercept methods for determining contributor proportions.

Main Methods:

• Utilized HTS/MPS SNP panels for analyzing complex DNA mixtures.
• Developed and applied three distinct statistical approaches: mean, median, and slope methods.
• Compared major:minor allele ratios or counts, unique to each contributor, to estimate proportion.

Main Results:

• The mean, median, and slope methods provided accurate estimations of individual DNA contributions.
• Estimates were typically within 5% of the planned experimental contributions in defined mixtures.
• These methods offer a reliable way to quantify individual proportions in complex SNP-based forensic samples.

Conclusions:

• The developed mean, median, and slope methods are effective for estimating individual DNA contributions in forensic mixtures analyzed by HTS/MPS SNP panels.
• These approaches provide a valuable tool for forensic scientists dealing with complex DNA samples.
• SNP-based HTS offers a robust alternative or complement to traditional STR analysis for mixture deconvolution.