Effect of agonal and postmortem factors on gene expression profile: quality control in microarray analyses of...

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Concerns exist regarding the impact of agonal conditions on ribonucleic acid (RNA) integrity in postmortem brain tissue.
• Maintaining RNA integrity is vital for reliable gene expression analysis in neurological and psychiatric research.

Purpose of the Study:

• To investigate the influence of agonal factors on RNA integrity and gene expression profiles.
• To propose a method for assessing RNA integrity in postmortem samples.
• To highlight the importance of accounting for agonal state in gene expression studies.

Main Methods:

• Analysis of gene expression profiles using microarrays.
• Evaluation of RNA integrity using the proposed Average Correlation Index.
• Comparison of the effects of agonal factors versus demographic and postmortem variables.

Main Results:

• Agonal factors, including coma and hypoxia, were found to significantly affect RNA integrity and gene expression.
• Demographic factors (gender, age) and postmortem interval had a lesser impact on gene expression profiles.
• The Average Correlation Index demonstrated utility in evaluating RNA integrity based on microarray profile similarity.

Conclusions:

• Agonal conditions are critical confounders in postmortem brain gene expression studies.
• The Average Correlation Index offers a novel approach to quantify RNA integrity.
• Minimizing variance from agonal factors is essential for detecting subtle gene expression differences, particularly in psychiatric research.