Buchwald, D, Herrell, R, Ashton, S et al. · Twin research : the official journal of the International Society for Twin Studies · 1999 · DOI
Researchers created a registry of twin pairs where at least one person had chronic fatigue to better understand the condition. They recruited 204 twin pairs through support groups, doctors, and other sources, and had 177 complete their detailed questionnaires and phone interviews. This registry was designed to help scientists study what causes chronic fatigue and whether genetics or life circumstances play a bigger role.
This registry provides a structured resource for twin studies that can help researchers disentangle genetic versus environmental factors contributing to ME/CFS and chronic fatigue. Understanding the relative contributions of heredity and life circumstances is crucial for identifying risk factors and developing targeted interventions for patients.
This registry study does not establish causation for any risk factors or determine whether genetic or environmental factors actually cause chronic fatigue—it only creates an infrastructure for such research. The reliance on volunteer recruitment may introduce selection bias, meaning the twins studied may not fully represent all people with chronic fatigue. The study does not present genetic or twin modeling analyses that would directly address heritability questions.
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
Buchwald, D, Herrell, R, Ashton, S, Belcourt, M, Schmaling, K, & Goldberg, J (1999). The Chronic Fatigue Twin Registry: method of construction, composition, and zygosity assignment.. Twin research : the official journal of the International Society for Twin Studies. https://doi.org/10.1375/136905299320565870
BibTeX
@article{mecfsatlas-buchwald-1999-chronic-fatigue,
author = {Buchwald, D and Herrell, R and Ashton, S and Belcourt, M and Schmaling, K and Goldberg, J},
title = {The Chronic Fatigue Twin Registry: method of construction, composition, and zygosity assignment.},
journal = {Twin research : the official journal of the International Society for Twin Studies},
year = {1999},
doi = {10.1375/136905299320565870},
note = {PubMed: 10555131},
url = {https://www.mecfsatlas.com/evidence/buchwald-1999-chronic-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/buchwald-1999-chronic-fatigue
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