Developmental validation of the SF 28CS typing system: a robust 6-dye multiplex for forensic human identification.

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Short tandem repeats (STRs) are highly polymorphic markers crucial for human identification and kinship analysis.
• Existing multiplex PCR assays face challenges with degraded samples and complex mixtures.

Purpose of the Study:

• To report the developmental validation of the novel SF28CS typing system.
• To assess the system's sensitivity, specificity, robustness, and discriminatory power for forensic applications.

Main Methods:

• Developmental validation of a six-dye multiplex PCR assay amplifying 28 loci (23 autosomal STRs, 3 Y-STRs, 1 Y-chromosomal indel, Amelogenin).
• Testing using Applied Biosystems 3500 Genetic Analyzer following SWGDAM guidelines.
• Evaluation included sensitivity, species specificity, inhibitor tolerance, mixture analysis, and population studies.

Main Results:

• The SF28CS system demonstrated high sensitivity (62.5 pg DNA) and successfully genotyped challenging forensic samples.
• The assay showed stability against PCR inhibitors and reliable mixture resolution up to 1:4 contributor ratios.
• Population studies confirmed high discriminatory power, with superior robustness for degraded samples and complex mixtures compared to existing kits.

Conclusions:

• The SF28CS system is a sensitive, reliable, and comprehensive tool for forensic casework and human identification.
• Its inclusion of Y-chromosomal markers enhances utility in kinship testing and male identification.
• The validated system supports application in forensic databases and challenging identification scenarios.