Corfield, Elizabeth C, Martin, Nicholas G, Nyholt, Dale R · Twin research and human genetics : the official journal of the International Society for Twin Studies · 2017 · DOI
This study looked at whether fatigue runs in families and whether genetics plays a role. Researchers compared identical twins (who share all genes) with fraternal twins (who share about half) and found that when one twin had fatigue, their identical twin was more likely to also have fatigue than fraternal twins were. The results suggest that about 40% of fatigue differences between people are due to genetics, while the remaining 60% comes from environmental factors or lifestyle.
Understanding that fatigue has a heritable genetic component validates that it is not purely psychological or a matter of willpower, which can reduce stigma for ME/CFS patients. This finding supports the biological basis of fatigue and may help guide future research into identifying specific genetic and environmental factors that trigger or worsen the condition.
This study does not identify the specific genes responsible for fatigue or explain the 60% of fatigue variation due to environmental factors. It does not prove that inheriting genes for fatigue will necessarily cause ME/CFS, as genetic predisposition requires environmental triggers or additional factors to manifest as disease. The study measured general fatigue over a few weeks rather than chronic fatigue syndrome specifically, so findings may not fully apply to ME/CFS populations.
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 →
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