A Twin Study of Chronic Fatigue

Department of Psychiatry and Behavioral Sciences, University of Washington Seattle, Seattle, Washington, United States
Psychosomatic Medicine (Impact Factor: 3.47). 11/2001; 63:936-943. DOI: 10.1097/00006842-200111000-00012
Source: PubMed


OBJECTIVE: The etiology of chronic fatigue syndrome is unknown, but genetic influences may be important in its expression. Our objective was to assess the role of genetic and environmental factors in unexplained chronic fatigue. METHODS: A classic twin study was conducted using 146 female-female twin pairs, of whom at least one member reported > or =6 months of fatigue. After completing questionnaires on symptoms, zygosity, physical health, and a psychiatric interview, twins were classified using three increasingly stringent definitions: 1) chronic fatigue for > or =6 months, 2) chronic fatigue not explained by exclusionary medical conditions, and 3) idiopathic chronic fatigue not explained by medical or psychiatric exclusionary criteria of the chronic fatigue syndrome case definition. Concordance rates in monozygotic and dizygotic twins were calculated for each fatigue definition along with estimates of the relative magnitude of genetic and environmental influences on chronic fatigue. RESULTS: The concordance rate was higher in monozygotic than dizygotic twins for each definition of chronic fatigue. For idiopathic chronic fatigue, the concordance rates were 55% in monozygotic and 19% in dizygotic twins (p =.042). The estimated heritability in liability was 19% (95% confidence interval = 0-56) for chronic fatigue > or =6 months, 30% (95% confidence interval = 0-81) for chronic fatigue not explained by medical conditions, and 51% (95% confidence interval = 7-96) for idiopathic chronic fatigue. CONCLUSIONS: These results provide evidence supporting the familial aggregation of fatigue and suggest that genes may play a role in the etiology of chronic fatigue syndrome.

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    • "CFS may have a familial predisposition as relatives of patients with CFS may not necessarily meet the criteria for CFS but may be more prone to experience some of the symptoms of CFS (Walsh et al., 2001). Although twin studies allude to the existence of a genetic predisposition to CFS, this may be higher among monozygotic twins compared to dizygotic twins (Buchwald et al., 2001). Twins with CFS may share similar symptoms and experience the same level of severity in CFS related symptoms (Claypoole et al., 2007). "

    Full-text · Chapter · Feb 2012
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    • "Subjects were classified based on the 1994 Centers for Disease Control and Prevention (CDC) CFS case definition (Fukuda, et al., 1994). This cohort has been extensively evaluated in a number of studies regarding the biology of CFS (Aaron, et al., 2002; Aaron, et al., 2001; Armitage, et al., 2009; Ball, et al., 2004; Buchwald, et al., 2001; K. Claypoole, et al., 2001; K. H. Claypoole, et al., 2007; Herrell, et al., 2002; Lewis, et al., 2001; Mahurin, et al., 2004; Poole, Herrell, Ashton, Goldberg, & Buchwald, 2000; Roy-Byrne, et al., 2002; Watson, Jacobsen, Goldberg, Kapur, & Buchwald, 2004; Watson, et al., 2003), and our group has previously reported on immune parameters associated with CFS (Koelle, et al., 2002; Sabath, et al., 2002). From the original samples obtained in 2001 as described in (Koelle, et al., 2002; Sabath, et al., 2002), material was available for this study from 21 same-sex twin pairs (19 female, 2 male). "
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    ABSTRACT: A recent report suggested an association between xenotropic murine leukemia virus-related virus (XMRV) and chronic fatigue syndrome (CFS). If confirmed, this would suggest that antiretroviral therapy might benefit patients suffering from CFS. We validated a set of assays for XMRV and evaluated the prevalence of XMRV in a cohort of monozygotic twins discordant for CFS. Stored peripheral blood mononuclear cell (PBMC) samples were tested with 3 separate polymerase chain reaction (PCR) assays (one of which was nested) for XMRV DNA, and serum/plasma was tested for XMRV RNA by reverse transcription (RT)-PCR. None of the PBMC samples from the twins with CFS or their unaffected co-twins was positive for XMRV, by any of the assays. One plasma sample, from an unaffected co-twin, was reproducibly positive by RT-PCR. However, serum from the same day was negative, as was a follow-up plasma sample obtained 2 days after the positive specimen. These data do not support an association of XMRV with CFS.
    Full-text · Article · Sep 2011 · Diagnostic microbiology and infectious disease
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    • "There are numerous studies suggesting that genes might play a role in the development of CFS or in its progression [19-21]. Several twin studies have examined genetic vs. environmental determinants of CFS [21-24]. "
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    ABSTRACT: Chronic Fatigue Syndrome (CFS) came to attention in the 1980s, but initial investigations did not find organic causes. Now decades later, the etiology of CFS has yet to be understood, and the role of genetic predisposition in CFS remains controversial. Recent reports of CFS association with the retrovirus xenotropic murine leukemic virus-related virus (XMRV) or other murine leukemia related retroviruses (MLV) might also suggest underlying genetic implications within the host immune system. We present analyses of familial clustering of CFS in a computerized genealogical resource linking multiple generations of genealogy data with medical diagnosis data of a large Utah health care system. We compare pair-wise relatedness among cases to expected relatedness in the Utah population, and we estimate risk for CFS for first, second, and third degree relatives of CFS cases. We observed significant excess relatedness of CFS cases compared to that expected in this population. Significant excess relatedness was observed for both close (p <0.001) and distant relationships (p = 0.010). We also observed significant excess CFS relative risk among first (2.70, 95% CI: 1.56-4.66), second (2.34, 95% CI: 1.31-4.19), and third degree relatives (1.93, 95% CI: 1.21-3.07). These analyses provide strong support for a heritable contribution to predisposition to Chronic Fatigue Syndrome. A population of high-risk CFS pedigrees has been identified, the study of which may provide additional understanding.
    Full-text · Article · May 2011 · BMC Neurology
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