SNP Markers as Additional Information to Resolve Complex Kinship Cases.

Area of Science:

• Forensic genetics
• Human identification

Background:

• Autosomal short tandem repeat (STR) markers are standard in forensic DNA profiling for human identification.
• Complex kinship investigations sometimes yield insufficient data from STR markers, leading to low likelihood ratios (LRs).
• Single nucleotide polymorphisms (SNPs) are proposed as a supportive or alternative tool to STR typing.

Purpose of the Study:

• To evaluate the utility of SNP genotyping as a complement to STR analysis in complex forensic casework.
• To assess the impact of combined STR and SNP analysis on the evidential value in paternity testing.

Main Methods:

• Analysis of 7 complex paternity cases using a standard battery of STRs.
• Genotyping of 52 human identification SNPs (SNPforID 52plex panel) using SNaPshot methodology.
• Capillary electrophoresis for data acquisition.

Main Results:

• SNP analysis, when added to STR typing, increased total parentage index (PI) values by at least a factor of 4.
• The combined approach significantly enhanced the evidential weight (Essen-Möller's W value) in forensic casework.
• SNP genotyping provided crucial supplementary data for challenging identification scenarios.

Conclusions:

• SNP genotyping is a valuable complement to STR information in difficult disputed paternity cases.
• This approach is particularly effective for close relative individualization and complex pedigrees with endogamous relationships.
• The integration of SNPs enhances the reliability and discriminatory power of DNA profiling in forensic science.