A comparative study for the isolation of exogenous trace DNA from fingernails

Area of Science:

• Forensic Science
• Molecular Biology
• Genetics

Background:

• Fingernails from assault cases are vital for DNA testing.
• Limited research exists on optimal methods for foreign DNA recovery from fingernails.
• Effective methods must balance foreign DNA extraction with minimizing endogenous DNA.

Purpose of the Study:

• To compare three sampling methods for fingernail DNA analysis.
• To identify a method that maximizes foreign DNA recovery.
• To minimize endogenous DNA contamination during sample collection.

Main Methods:

• Comparison of swabbing, PBS soak, and lysis buffer soak methods.
• DNA extraction and quantification using Tecan HIDEVO150 robot.
• Probabilistic genotyping software (STRmix™) for mixture interpretation.

Main Results:

• Swabbing and lysis buffer soak methods effectively removed foreign DNA.
• Lysis buffer soak extracted more degraded endogenous female DNA.
• Swab samples yielded marginally higher likelihood ratios for foreign DNA donors.

Conclusions:

• Swabbing is the optimal method for recovering foreign DNA from fingernails.
• Swabbing minimizes endogenous DNA removal compared to lysis buffer soak.
• This method enhances forensic DNA analysis in assault cases.