Improving the system power of complex kinship analysis by combining multiple systems.

Area of Science:

• Forensic genetics
• Human genetics
• Molecular biology

Background:

• Complex kinship analysis is crucial in forensic genetics.
• Evaluating system power for second- and third-degree kinship analysis is essential.
• Commercial forensic typing kits utilize capillary electrophoresis (CE) and next-generation sequencing (NGS) platforms.

Purpose of the Study:

• To assess the system power of 55 STRs and 94 SNPs for kinship analysis.
• To compare likelihood ratios (LRs) derived from length (LR_length) versus sequence (LR_sequence) polymorphism information.
• To evaluate the effectiveness of different marker sets in distinguishing second- and third-degree kinship.

Main Methods:

• Utilized 55 STRs and 94 SNPs from three CE-based and one NGS-based forensic typing kit.
• Calculated LR_length and LR_sequence using simulation and true pedigree samples.
• Estimated sensitivity, specificity, and effectiveness for kinship discrimination.

Main Results:

• LR_sequence generally yielded higher values than LR_length.
• System power for kinship analysis improved with more markers and LR_sequence.
• 55 STRs on CE platform showed comparable power to 40 STRs plus 94 SNPs on CE/NGS platforms.
• High effectiveness (94.43%) with low error ratio (<0.001) for second-degree kinship using sequence information from 55 STRs and 94 SNPs.

Conclusions:

• STRs and SNPs, particularly using sequence information, are powerful tools for kinship analysis.
• The evaluated markers are highly effective for second-degree kinship and suitable for third-degree kinship analysis.
• NGS and CE platforms offer comparable system power for kinship determination.