Match statistics for sequence-based alleles in profiles from forensic PCR-mps kits

Area of Science:

• Forensic genetics
• Genomic analysis
• Population genetics

Background:

• Massively parallel sequencing (MPS) offers advanced forensic genetic analysis.
• A key challenge for MPS implementation in casework is the lack of comprehensive population frequency databases for SNP-STR haplotypes.
• Existing databases are often tied to specific analytical parameters, such as flank trim sites.

Purpose of the Study:

• To introduce a method for calculating match probabilities when using MPS kits with different flank trim sites than those used to generate population frequency data.
• To provide a flexible framework for comparing results across different MPS kits and databases.
• To enable the comparison of MPS and capillary electrophoresis (CE) profiles.

Main Methods:

• Development of a procedure to calculate SNP-STR haplotype frequencies.
• Application of the procedure to address discrepancies in flank trim sites between casework samples and population databases.
• Framework designed for compatibility with various MPS kits and capillary electrophoresis (CE) data.

Main Results:

• A method is described to calculate match probabilities for SNP-STR haplotypes detected with MPS, even when using different flank trim sites than those in the reference database.
• The procedure ensures accurate frequency calculations regardless of the specific MPS kit or database combination.
• The framework accommodates comparisons between MPS and CE profiles.

Conclusions:

• The developed procedure removes a significant barrier to the routine implementation of MPS in forensic casework.
• Accurate calculation of match probabilities is achievable despite variations in MPS analytical parameters.
• This approach enhances the utility of MPS in forensic investigations and supports the integration of MPS and CE data.