Developmental validation study of a 24-plex Y-STR direct amplification system for forensic application.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Forensic DNA analysis relies on Y-short tandem repeat (Y-STR) loci for male lineage identification.
• Degraded DNA samples and complex mixtures pose challenges in forensic investigations.
• Validated Y-STR systems are crucial for accurate and reliable forensic casework.

Purpose of the Study:

• To present validation data for the Microreader™ 24Y Direct ID System.
• To evaluate the performance of 24 Y-STR loci in forensic applications, including degraded DNA and mixtures.
• To assess the genetic diversity and forensic parameters of these loci in the Jiangsu Han population.

Main Methods:

• Developmental validation studies conducted according to SWGDAM guidelines.
• Included PCR-based studies, sensitivity, species specificity, stability, accuracy, reproducibility, mixture, and case-type sample analyses.
• Investigated genetic diversity and forensic parameters (haplotype diversity, discrimination capacity) in the Jiangsu Han population.

Main Results:

• The 24Y Direct System demonstrated high detection accuracy, species specificity, anti-inhibition effect, and sensitivity (minimum detection: 125 pg).
• Eight Y-STR loci with PCR product sizes < 220 bp enhance degraded DNA analysis.
• The system showed high discriminating ability in mixtures (female:male ratio < 3.2:1, male:male ratio < 1:9) and compatibility with various biological samples.
• Haplotype diversity (HD) and discrimination capacity (DC) were 0.9952 and 0.8500, respectively, indicating high polymorphism.

Conclusions:

• The Microreader™ 24Y Direct ID System is a validated, sensitive, and accurate tool for forensic identification.
• The 24 Y-STR loci are highly polymorphic in the Jiangsu Han population, valuable for forensic and population genetic studies.
• The system's performance with degraded DNA and mixtures makes it suitable for challenging forensic cases.