Improving STR typing for low template DNA by abasic-site-mediated semi-linear preamplification

Area of Science:

• Forensic Genetics
• Molecular Biology
• Biochemistry

Background:

• Low template DNA (LT-DNA) analysis presents challenges in obtaining complete short tandem repeat (STR) profiles.
• Preamplification strategies are crucial for maximizing genetic information recovery in STR typing.

Purpose of the Study:

• To investigate an efficient amplification method for LT-DNA analysis.
• To enhance STR profiling from minute DNA quantities using a novel preamplification technique.

Main Methods:

• Developed and applied a semi-linear amplification (abSLA PCR) method utilizing abasic sites in primers.
• Optimized abasic site positioning (8th-10th from 3' end) to facilitate PCR amplification.
• Implemented a 4-plex STR pre-amplification targeting specific loci (D8S1179, D21S11, D7S820, CSF1PO) with the Identifiler Plus kit.

Main Results:

• The abSLA PCR method efficiently deleted primer-binding sites on PCR products, enabling semi-linear amplification.
• A significant increase in the recovery of STR loci was observed when analyzing low template genomic DNA and single cells.
• Successful application of the 4-plex STR pre-amplification demonstrated enhanced STR typing capabilities.

Conclusions:

• The abasic site-mediated semi-linear amplification (abSLA PCR) is an effective strategy for improving LT-DNA analysis.
• This method significantly enhances the recovery of genetic information, facilitating conventional STR typing in forensic genetics.
• abSLA PCR offers a valuable tool for overcoming challenges in analyzing degraded or limited DNA samples.