Bayesian Framework for Detecting Gene Expression Outliers in Individual Samples

Area of Science:

• Bioinformatics
• Computational Biology
• Genomics

Background:

• Targeting upregulated genes with antineoplastics requires accurate quantification of gene expression.
• Quantifying upregulation in single patient samples is challenging due to high intersample variance and limited availability of matched unaffected tissue samples.
• Existing differential expression tools often fail to accommodate comparisons to single patient samples.

Purpose of the Study:

• To develop a Bayesian statistical framework for robust gene expression outlier detection in individual patient samples.
• To enable accurate quantification of gene over- and underexpression without a manually selected comparison set.
• To address limitations in current methods for analyzing single-sample gene expression data in clinical settings.

Main Methods:

• A Bayesian statistical framework was developed for outlier detection in gene expression data.
• The method generates a consensus background distribution for each gene using all available data, eliminating the need for manual comparison set selection.
• This approach quantifies gene over- and underexpression relative to the consensus distribution.

Main Results:

• The method robustly quantifies gene overexpression, even with suboptimal or mismatched comparison samples.
• It successfully identifies appropriate comparison sets from mixed-lineage samples.
• The framework rediscovers known gene-cancer expression patterns, demonstrating its validity on simulated and real-world data.

Conclusions:

• This exploratory method is effective for identifying expression outliers in comparative RNA sequencing (RNA-seq) analysis of individual samples.
• The approach is being considered by Treehouse, a pediatric precision medicine group, for processing its RNA-seq data to identify therapeutic leads.
• The framework offers a novel solution for single-sample gene expression analysis in precision medicine.