Search for More Effective Microsatellite Markers for Forensics With Next-Generation Sequencing

Area of Science:

• Forensic Genetics
• Genomics
• Population Genetics

Background:

• The 13 core short tandem repeat (STR) loci, established by the FBI's CODIS program, are standard forensic genetic markers.
• Existing CODIS loci exhibit population biases and reduced sensitivity, and large databases increase the risk of false matches.
• Whole genome sequencing offers potential for identifying more discriminating and sensitive STR markers.

Purpose of the Study:

• To develop and validate an algorithm for identifying novel STR markers with high discriminative power from next-generation sequencing data.
• To create customized STR marker sets for specific populations with defined thresholds for forensic applications.
• To compare the performance of newly identified STR markers against the existing CODIS 13 loci for identity and paternity testing.

Main Methods:

• Developed a computational algorithm to identify STR markers with high discriminative abilities from whole genome sequencing data.
• Applied the algorithm to 320 Chinese individuals from the 1000 Genomes Project to select customized STR loci.
• Evaluated the selected STR loci for combined power of discrimination, combined probability of exclusion, and frequency of DNA profile (FDP) using statistical tests and simulated databases.

Main Results:

• The algorithm successfully identified STR loci with higher combined powers of discrimination and exclusion than the CODIS 13 loci.
• Selected STR sets demonstrated lower frequency of DNA profile (FDP) and reduced database matching probabilities, even in a 10 billion entry database.
• Novel STR loci significantly decreased the chance of random profile matches, minimizing false positives and reducing risks in familial searches.
• Simulated paternity testing data showed improved accuracy with the selected STRs, yielding lower probabilities of false inclusions and exclusions.

Conclusions:

• The developed algorithm effectively identifies superior STR markers for forensic use, surpassing the discriminative capabilities of current CODIS loci.
• Customized STR sets enhance individual identification accuracy and reduce false match probabilities in forensic databases.
• These advanced STR markers offer significant improvements for identity testing, paternity testing, and familial searches, enhancing forensic investigation reliability.