Cited by 1,930Gene expression and cancer classificationBioinformatics and Genomic NetworksSingle-cell and spatial transcriptomics

Capturing Heterogeneity in Gene Expression Studies by Surrogate Variable Analysis

Open access
Leek, Jeffrey T, Storey, John D·2007·PLoS Genetics

Abstract

It has unambiguously been shown that genetic, environmental, demographic, and technical factors may have substantial effects on gene expression levels. In addition to the measured variable(s) of interest, there will tend to be sources of signal due to factors that are unknown, unmeasured, or too complicated to capture through simple models. We show that failing to incorporate these sources of heterogeneity into an analysis can have widespread and detrimental effects on the study. Not only can this reduce power or induce unwanted dependence across genes, but it can also introduce sources of spurious signal to many genes. This phenomenon is true even for well-designed, randomized studies. We introduce "surrogate variable analysis" (SVA) to overcome the problems caused by heterogeneity in expression studies. SVA can be applied in conjunction with standard analysis techniques to accurately capture the relationship between expression and any modeled variables of interest. We apply SVA to disease class, time course, and genetics of gene expression studies. We show that SVA increases the biological accuracy and reproducibility of analyses in genome-wide expression studies.

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  • Surrogate variable analyses revealed 4 significant SVA vectors that were used as covariates in the model to correct for technical artefacts and hidden confounds.

    “Surrogate variable analyses (SVAs) revealed 4 significant SVA vectors that were used as covariates in the model to correct for technical artefacts and hidden confounds (Leek & Storey, 2007).”

    From DNA methylation of NR3C1 and FKBP5 is associated with posttraumatic stress disorder, posttraumatic growth, and resilience. (2020) · cites this paper as Leek & Storey, 2007

    The Results section (“Surrogate Variables”; page not available) says SVA identifies significant vectors and incorporates the resulting surrogate variables as covariates in subsequent analyses. The paper supports using them to account for unmodeled variation, but it does not report that this citing analysis found four significant vectors or used four in its model. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • sva and PEER, which use data across all sites, removed 85.1% to 87.7% of the original total false positive DEGs.

    “Some methods (specifically sva and PEER) that leveraged all data across all sites were quite successful at ameliorating the high rate of false positives (Fig. 1, Supplementary Fig. 2), removing 85.1% to 87.7% of the original total false positive DEGs.”
  • More than 85% of RNA-seq false positives could be removed by subtracting latent variable effects identified by sva or PEER through joint analysis of all genes across multiple sites, without decreasing sensitivity or specificity of DEG detection.

    “However, the majority of RNA-seq false positives (>85%) could successfully be removed by subtracting the effects of latent variables identified by either sva26,27 or PEER30, which could be achieved by jointly analyzing the set of measurements of all genes across multiple sites, without a decrease in the sensitivity or specificity of DEG detection at each site or across sites.”
  • Surrogate variable correction was used to account for unmeasured confounders, a standard approach.

    “We used surrogate variable correction in our analyses to account for such unmeasured confounders (43), which is a standard approach (44).”
  • After adjusting for surrogate variables, similar tissue and cell types clustered together across experiments.

    “We used surrogate variable analysis (SVA) and 26 loosely described “biologic clusters” of tissues and cells to clearly demonstrate that, after adjusting for surrogate variables, similar tissue and cell types clustered together across experiments (Supplemental Fig. S3; Leek and Storey 2007).”

    From Toward the human cellular microRNAome (2017) · cites this paper as Leek and Storey 2007

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Research works printed but not linked: 1

  1. Mardia KV Kent JT Bibby JM 1980 Multivariate analysis London Academic Press

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Authors
Leek, J. T., & Storey, J. D.
Affiliations
University of Washington (US)
Corresponding author
Storey, John D
Venue
PLoS Genetics
Published
2007-09-28
Volume
3
Issue
9
Pages
e161
ISSN
  • 1553-7390 (ISSN-L)
  • 1553-7404
OpenAlex
W2137499573
Cited by
1,930
References
46
Citations by year
2026: 77 · 2025: 114 · 2024: 131 · 2023: 126 · 2022: 155 · 2021: 195 · 2020: 177 · 2019: 156 · 2018: 141 · 2017: 143 · 2016: 112 · 2015: 79 · 2014: 87 · 2013: 74 · 2012: 54
FWCI
8.49
Type
journal article
Language
en
Open access
Locations
  • PLoS Genetics (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, other-oa)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Figshare (submittedVersion, cc-by)
Funders
  • National Institutes of Health
  • National Human Genome Research Institute (R01HG002913)
  • National Institute of General Medical Sciences (U54GM062119, U54 GM2119)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gene expression and cancer classification
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Bioinformatics and Genomic Networks
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Single-cell and spatial transcriptomics
Keywords
surrogate variable analysis, gene expression heterogeneity, unmeasured confounding, time-course expression, reproducibility, statistical power
MeSH terms
Algorithms, Breast Neoplasms, Computer Simulation, Data Interpretation, Statistical, Female, Humans, Kidney, Genetic Linkage, Mutation, Saccharomyces cerevisiae, Time Factors, Reproducibility of Results, Gene Expression, Genome, Human, Linear Models, Genome, Fungal, Genetic Heterogeneity, Genes, BRCA1, Quantitative Trait, Heritable, Oligonucleotide Array Sequence Analysis, Genes, BRCA2, Epigenesis, Genetic

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