Mass spectrometry-based cDNA profiling as a potential tool for human body fluid identification

Area of Science:

• Forensic Genetics
• Molecular Biology
• Biochemistry

Background:

• mRNA markers are crucial for identifying human body fluids (blood, saliva, semen) in forensic science.
• Existing methods like quantitative polymerase chain reaction (qPCR) have limitations, particularly in multiplexing due to fluorescent dye constraints.
• There's a need for alternative molecular techniques to assess novel body fluid-specific mRNA markers.

Purpose of the Study:

• To evaluate matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) as a novel method for human body fluid identification.
• To assess the performance of MALDI-TOF MS for cDNA profiling of venous blood, saliva, and semen.
• To explore a fluorescent dye-free approach for body fluid identification in forensic casework.

Main Methods:

• Exploration of MALDI-TOF MS for cDNA profiling of human body fluids.
• Amplification of body fluid-specific mRNA markers (e.g., phosphoglycerate kinase 1 - PGK1) from venous blood, saliva, and semen.
• Analysis of amplified cDNA using MALDI-TOF MS with 20pg input amounts.

Main Results:

• MALDI-TOF MS demonstrated 100% specificity in identifying body fluid-specific markers, detecting them in the correct fluid (blood, saliva, or semen) and not in others.
• The study identified phosphoglycerate kinase 1 (PGK1) as a candidate marker.
• MALDI-TOF MS emerged as a potential fluorescent dye-free alternative for body fluid identification.

Conclusions:

• MALDI-TOF MS is a viable, dye-free alternative technique for human body fluid identification via cDNA profiling in forensic genetics.
• Challenges remain, including low mRNA quantity and degradation from environmental factors, extraction, and storage, hindering widespread casework implementation.
• Further research is needed to overcome these limitations for robust application in forensic settings.