[Correlation between RNA Expression Level and Early PMI in Human Brain Tissue]

Area of Science:

• Forensic Science
• Molecular Biology
• Genomics

Background:

• Accurate postmortem interval (PMI) estimation is crucial in forensic investigations.
• RNA degradation patterns in brain tissue offer potential biomarkers for PMI determination.
• Identifying stable RNA reference markers is essential for reliable molecular analysis.

Purpose of the Study:

• To investigate the correlation between RNA marker expression levels and early postmortem interval (PMI) in human brain tissue.
• To identify suitable internal reference RNA markers for accurate PMI estimation.
• To evaluate the utility of specific RNA markers in forensic science.

Main Methods:

• Total RNA was extracted from human brain tissue of individuals with known PMI (4.3–22.5 hours).
• Expression levels of eight RNA markers (including 5S rRNA, miRNA-9, miRNA-125b, β-actin, GAPDH) were quantified using real-time PCR.
• GeNorm software was used to screen for stable internal reference markers, and their relationship with age, gender, and cause of death was analyzed.

Main Results:

• 5S rRNA, miRNA-9, and miRNA-125b exhibited stable expression, independent of age, gender, or cause of death.
• The error rate for PMI estimation using β-actin was 24.6%, while GAPDH showed a higher error rate of 41.0%.
• The expression levels of these stable RNA markers were suitable for normalizing gene expression in early PMI studies.

Conclusions:

• 5S rRNA, miRNA-9, and miRNA-125b are validated as reliable internal reference markers for human brain tissue in early PMI estimations.
• The expression level of β-actin shows a significant correlation with PMI and can serve as an additional index for early PMI determination.
• These findings enhance the molecular toolkit for forensic scientists in estimating time since death.