Analysis of rapid HIT application to touch DNA samples

Area of Science:

• Forensic Science
• Molecular Biology
• Genetics

Background:

• Rapid DNA technology is widely used for reference profiles.
• Its application to high-template DNA sources is well-documented.
• Effectiveness for low-template DNA, like touch DNA, remains under investigation for forensic casework.

Purpose of the Study:

• To evaluate the Rapid HIT Intel cartridge for amplifying touch DNA.
• To assess its performance on various substrates commonly found in forensic investigations.
• To compare rapid DNA analysis with standard forensic DNA workflows.

Main Methods:

• Eight different items were touched in ten replicates.
• Samples were collected using tape lifts, swabs, and direct insertion.
• DNA profiles were generated and compared to standard processing methods.

Main Results:

• The Rapid HIT Intel cartridge showed variable success with touch DNA.
• Cable ties, fabric, and matchsticks yielded the best results, especially with direct insertion.
• Significant allele dropout and false homozygosity (32%-78%) were observed, influenced by substrate and RFU.
• Standard processing was superior for most substrates, except for a fabric swatch.

Conclusions:

• Rapid DNA technology, in its current form, is not suitable for routine touch DNA analysis in forensic casework.
• Further optimization is needed to overcome limitations in low-template DNA analysis.
• Direct insertion may be advantageous for small samples, but absorbent substrates should be avoided.