A novel multiplex of 12 multicopy Y-STRs for forensic application

Area of Science:

• Forensic Genetics
• Molecular Biology
• Human Genetics

Background:

• Y chromosomal short tandem repeats (Y-STRs) are crucial in forensic science for paternity and sexual assault cases.
• Current Y-STR kits often rely on single-copy markers, limiting discriminatory power, especially for related males.
• There is a need for Y-STR assays with enhanced discrimination capabilities.

Purpose of the Study:

• To develop and validate a novel Y-STR multiplex assay.
• To improve the discrimination power of Y-STR analysis, particularly for differentiating male relatives.
• To complement existing Y-STR kits with multicopy markers.

Main Methods:

• Development of a multiplex assay including twelve multicopy Y-STR loci, one single-copy Y-STR, and Amelogenin.
• Optimization of PCR conditions, including an annealing temperature of 59°C and 28 cycles.
• Validation of the assay for sensitivity, inhibitor tolerance, mixture analysis, species specificity, and genetic diversity.

Main Results:

• The assay successfully generated full DNA profiles from 0.125 ng of male DNA.
• The system demonstrated robustness against inhibitors like hematin, EDTA, and humic acid.
• High sensitivity was shown in detecting male DNA in male/female mixtures (1:800 ratio), with good sizing precision and species specificity.
• Most loci exhibited gene diversity values above 0.7, indicating high discrimination capacity.

Conclusions:

• The novel Y-STR multiplex assay provides enhanced discrimination power for forensic applications.
• The assay is sensitive, robust to inhibitors, and effective in mixture analysis.
• This new kit has significant potential for improving the identification of unrelated and related males in forensic investigations.