Byrnes, Andrea, Jacks, Andreas, Dahlman-Wright, Karin et al. · PloS one · 2009 · DOI
Researchers compared blood cells from 44 people with ME/CFS to their identical twins who do not have the illness, looking for genetic differences that might explain the disease. Despite careful testing using advanced technology, they found no differences in how genes were expressed between the two groups. This suggests that if previous studies claimed to find biomarkers (biological signs) of ME/CFS in blood, those findings may have been due to errors in how the studies were conducted rather than real biological differences.
This well-controlled study challenges the validity of previously reported blood-based biomarkers for ME/CFS, which is critical because misidentified biomarkers could misdirect research and clinical efforts. The rigorous twin-pair design eliminates genetic and environmental confounders that plague typical case-control studies, making the negative findings particularly informative about the reliability of other CFS transcriptome research.
This study does not prove that ME/CFS has no biological basis or that biomarkers do not exist elsewhere in the body (e.g., cerebrospinal fluid, muscle tissue, or other tissues). It also does not establish whether gene expression changes occur under specific conditions (e.g., post-exertional malaise) or in cell types other than peripheral blood leukocytes. The findings reflect this specific methodology and time point, not the absence of all biological abnormalities in ME/CFS.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Byrnes, Andrea, Jacks, Andreas, Dahlman-Wright, Karin, Evengard, Birgitta, Wright, Fred A, Pedersen, Nancy L, et al. (2009). Gene expression in peripheral blood leukocytes in monozygotic twins discordant for chronic fatigue: no evidence of a biomarker.. PloS one. https://doi.org/10.1371/journal.pone.0005805
BibTeX
@article{mecfsatlas-byrnes-2009-gene-expression,
author = {Byrnes, Andrea and Jacks, Andreas and Dahlman-Wright, Karin and Evengard, Birgitta and Wright, Fred A and Pedersen, Nancy L and Sullivan, Patrick F},
title = {Gene expression in peripheral blood leukocytes in monozygotic twins discordant for chronic fatigue: no evidence of a biomarker.},
journal = {PloS one},
year = {2009},
doi = {10.1371/journal.pone.0005805},
note = {PubMed: 19503787},
url = {https://www.mecfsatlas.com/evidence/byrnes-2009-gene-expression},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/byrnes-2009-gene-expression
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