Direct PCR amplification from saliva sample using non-direct multiplex STR kits for forensic DNA typing

Area of Science:

• Forensic Science
• Molecular Biology
• Genetics

Background:

• Multiplex PCR-based Short Tandem Repeat (STR) analysis is crucial for forensic, medical, and anthropological applications.
• Commercially available multiplex kits (4-6 dyes) are widely used for amplifying multiple STR loci from biological samples.
• Routine forensic DNA typing involves DNA extraction and quantification, which are time-consuming and resource-intensive.

Purpose of the Study:

• To evaluate the efficacy of non-direct multiplex STR kits for direct amplification of DNA from saliva samples.
• To develop and validate a direct PCR amplification protocol that omits DNA extraction and quantification steps.
• To assess the cost-effectiveness and time efficiency of the developed protocol without compromising DNA profile quality.

Main Methods:

• Direct amplification of 103 saliva samples using thirteen non-direct multiplex STR kits (4, 5, and 6 dyes).
• Samples were amplified without any pre-treatment, omitting DNA extraction and quantification steps.
• Validation of the direct PCR amplification protocol for forensic DNA typing.

Main Results:

• A validated direct PCR amplification protocol was established for reference saliva samples.
• The protocol achieved an 80% reduction in turnaround time.
• Complete DNA profiles meeting all quality parameters were successfully obtained from all tested samples.
• The method proved to be cost-effective and time-efficient.

Conclusions:

• Direct amplification using non-direct multiplex STR kits is a viable and efficient method for forensic DNA typing.
• The developed protocol significantly reduces turnaround time and lab costs.
• This represents the first report of direct DNA amplification using commonly used non-direct multiplex STR kits without sample pre-treatment.