| 1. |
- Purcell, Shaun M., et al.
(författare)
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Common polygenic variation contributes to risk of schizophrenia and bipolar disorder
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 460:7256, s. 748-752
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Tidskriftsartikel (refereegranskat)abstract
- Schizophrenia is a severe mental disorder with a lifetime risk of about 1%, characterized by hallucinations, delusions and cognitive deficits, with heritability estimated at up to 80%(1,2). We performed a genome-wide association study of 3,322 European individuals with schizophrenia and 3,587 controls. Here we show, using two analytic approaches, the extent to which common genetic variation underlies the risk of schizophrenia. First, we implicate the major histocompatibility complex. Second, we provide molecular genetic evidence for a substantial polygenic component to the risk of schizophrenia involving thousands of common alleles of very small effect. We show that this component also contributes to the risk of bipolar disorder, but not to several non-psychiatric diseases.
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| 2. |
- Byrnes, Andrea, et al.
(författare)
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Gene expression in peripheral blood leukocytes in monozygotic twins discordant for chronic fatigue : no evidence of a biomarker
- 2009
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:6, s. e5805-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chronic fatiguing illness remains a poorly understood syndrome of unknown pathogenesis. We attempted to identify biomarkers for chronic fatiguing illness using microarrays to query the transcriptome in peripheral blood leukocytes. METHODS: Cases were 44 individuals who were clinically evaluated and found to meet standard international criteria for chronic fatigue syndrome or idiopathic chronic fatigue, and controls were their monozygotic co-twins who were clinically evaluated and never had even one month of impairing fatigue. Biological sampling conditions were standardized and RNA stabilizing media were used. These methodological features provide rigorous control for bias resulting from case-control mismatched ancestry and experimental error. Individual gene expression profiles were assessed using Affymetrix Human Genome U133 Plus 2.0 arrays. FINDINGS: There were no significant differences in gene expression for any transcript. CONCLUSIONS: Contrary to our expectations, we were unable to identify a biomarker for chronic fatiguing illness in the transcriptome of peripheral blood leukocytes suggesting that positive findings in prior studies may have resulted from experimental bias.
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| 3. |
- Evengård, Birgitta, 1952-, et al.
(författare)
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The epidemiology of chronic fatigue in the Swedish Twin Registry
- 2005
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Ingår i: Psychological Medicine. - 0033-2917 .- 1469-8978. ; 35:9, s. 1317-1326
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Tidskriftsartikel (refereegranskat)abstract
- CFS-like illness may be more common that previously acknowledged. There is a marked increase in risk by gender. Previous reports that CFS is more prevalent in individuals in certain occupational categories were not confirmed and may have been due to confounding by gender.
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| 4. |
- Forlenza, Michael J, et al.
(författare)
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Epidemiology of cancer-related fatigue in the Swedish twin registry
- 2005
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Ingår i: Cancer. - : Wiley. - 0008-543X .- 1097-0142. ; 104:9, s. 2022-2031
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Tidskriftsartikel (refereegranskat)abstract
- A greater proportion of individuals who were listed in a national cancer registry reported experiencing fatigue compared with individuals in the general population.
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| 5. |
- Kato, K, et al.
(författare)
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A population-based twin study of functional somatic syndromes
- 2009
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Ingår i: Psychological Medicine. - : Cambridge University Press. - 0033-2917 .- 1469-8978. ; 39:3, s. 497-505
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The mechanisms underlying the co-occurrence of the functional somatic syndromes are largely unknown. No empirical study has explicitly examined how genetic and environmental factors influence the co-morbidity of these syndromes. We aimed to examine how the co-morbidity of functional somatic syndromes is influenced by genetic and environmental factors that are in common to the syndromes. METHOD: A total of 31318 twins in the Swedish Twin Registry aged 41-64 years underwent screening interviews via a computer-assisted telephone system from 1998 to 2002. Four functional somatic syndromes (chronic widespread pain, chronic fatigue, irritable bowel syndrome, and recurrent headache) and two psychiatric disorders (major depression and generalized anxiety disorder) were assessed using structured questions based on standard criteria for each illness in a blinded manner. RESULTS: Multivariate twin analyses revealed that a common pathway model with two latent traits that were shared by the six illnesses fit best to the women's data. One of the two latent traits loaded heavily on the psychiatric disorders, whereas the other trait loaded on all four of the functional somatic syndromes, particularly chronic widespread pain, but not on the psychiatric disorders. All illnesses except the psychiatric disorders were also affected by genetic influences that were specific to each. CONCLUSIONS: The co-occurrence of functional somatic syndromes in women can be best explained by affective and sensory components in common to all these syndromes, as well as by unique influences specific to each of them. The findings clearly suggest a complex view of the multifactorial pathogenesis of these illnesses.
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| 6. |
- Kato, Kenji, et al.
(författare)
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Chronic widespread pain and its comorbidities : a population-based study
- 2006
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Ingår i: Archives of Internal Medicine. - : American Medical Association (AMA). - 0003-9926 .- 1538-3679. ; 166:15, s. 1649-1654
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Tidskriftsartikel (refereegranskat)abstract
- Associations between CWP and most comorbidities are mediated by unmeasured genetic and family environmental factors in the general population. The extent of mediation via familial factors is likely to be disorder specific.
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| 7. |
- Kato, Kenji, et al.
(författare)
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Importance of genetic influences on chronic widespread pain
- 2006
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 54:5, s. 1682-1686
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Tidskriftsartikel (refereegranskat)abstract
- Individual differences in the likelihood of developing chronic widespread pain reflect modest genetic influences. There are no significant sex differences in the type or expression of the genes responsible for chronic widespread pain or in the magnitude of the relative importance of these influences on chronic widespread pain.
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| 8. |
- Kato, Kenji, et al.
(författare)
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Premorbid predictors of chronic fatigue
- 2006
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Ingår i: Archives of General Psychiatry. - : American Medical Association (AMA). - 0003-990X .- 1538-3636. ; 63:11, s. 1267-1272
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Tidskriftsartikel (refereegranskat)abstract
- Elevated premorbid stress is a significant risk factor for chronic fatigue-like illness, the effect of which may be buffered by genetic influences. Emotional instability assessed 25 years earlier is associated with chronic fatigue through genetic mechanisms contributing to both personality style and expression of the disorder. These findings suggest plausible mechanisms for chronic fatiguing illness.
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| 9. |
- Lichtenstein, Paul, et al.
(författare)
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Common genetic determinants of schizophrenia and bipolar disorder in Swedish families : a population-based study
- 2009
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 373:9659, s. 234-239
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Tidskriftsartikel (refereegranskat)abstract
- Background Whether schizophrenia and bipolar disorder are the clinical outcomes of discrete or shared causative processes is much debated in psychiatry. We aimed to assess genetic and environmental contributions to liability for schizophrenia, bipolar disorder, and their comorbidity. Methods We linked the multi-generation register, which contains information about all children and their parents in Sweden, and the hospital discharge register, which includes all public psychiatric inpatient admissions in Sweden. We identified 9 009 202 unique individuals in more than 2 million nuclear families between 1973 and 2004. Risks for schizophrenia, bipolar disorder, and their comorbidity were assessed for biological and adoptive parents, offspring, full-siblings and half-siblings of probands with one of the diseases. We used a multivariate generalised linear mixed model for analysis of genetic and environmental contributions to liability for schizophrenia, bipolar disorder, and comorbidity. Findings First-degree relatives of probands with either schizophrenia (n=35 985) or bipolar disorder (n=40 487) were at increased risk of these disorders. Half-siblings had a significantly increased risk (schizophrenia: relative risk [RR] 3.6, 95% CI 2.3-5.5 for maternal half-siblings, and 2.7, 1. 9-3 . 8 for paternal half-siblings; bipolar disorder: 4.5, 2.7-7.4 for maternal half-siblings, and 2.4, 1.4-4-1 for paternal half-siblings), but substantially lower than that of the full-siblings (schizophrenia: 9.0, 8.5-11 .6; bipolar disorder: 7.9, 7.1-8.8). When relatives of probands with bipolar disorder were analysed, increased risks for schizophrenia existed for all relationships, including adopted children to biological parents with bipolar disorder. Heritability for schizophrenia and bipolar disorder was 64% and 59%, respectively. Shared environmental effects were small but substantial (schizophrenia: 4.5%, 4.4%-7.4%; bipolar disorder: 3.4%, 2.3%-6.2%) for both disorders. The comorbidity between disorders was mainly (63%) due to additive genetic effects common to both disorders. Interpretation Similar to molecular genetic studies, we showed evidence that schizophrenia and bipolar disorder partly share a common genetic cause. These results challenge the current nosological dichotomy between schizophrenia and bipolar disorder, and are consistent with a reappraisal of these disorders as distinct diagnostic entities. Funding Swedish Council for Working Life and Social Research, and the Swedish Research Council.
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| 10. |
- Lichtenstein, Paul, et al.
(författare)
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Recurrence risks for schizophrenia in a Swedish national cohort
- 2006
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Ingår i: Psychological Medicine. - 0033-2917 .- 1469-8978. ; 36:10, s. 1417-1425
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Tidskriftsartikel (refereegranskat)abstract
- Background. Recurrence risk estimates for schizophrenia are fundamental to our understanding of this complex disease. Widely cited estimates are from small/older samples. If these estimates are biased upwards, then the rationale for molecular genetic studies of schizophrenia may not be as solid. Method. We created a population-based, Swedish national cohort by linking two Swedish national registers into a relational database (the Swedish Hospital Discharge Register and the MultiGeneration Register). Affection was defined as the lifetime presence of at least two in-patient hospitalizations with a core schizophrenia diagnosis. Results. Merging the Swedish national registers created a population-based cohort of 7 739 202 individuals of known parentage. The lifetime prevalence of the narrow definition of schizophrenia was 0(.)407% and we estimated that one in every 79 extended Swedish families had been impacted by schizophrenia. The proportion of affected families with multiple affected members was 3(.)81%. Recurrence risk estimates for all relative types were strikingly similar to those reported in smaller and older studies. For example, we estimated lambda(sibs) at 8(.)55 [95% confidence interval (CI) 7(.)86-9(.)57] compared with a literature estimate of 8(.)6. Conclusions. In the largest and most comprehensive sample yet studied, we confirm the accepted estimates of recurrence risks for schizophrenia, and provide more accurate estimates of recurrence risks of schizophrenia in relatives, an estimate of the familial impact of schizophrenia, and the multiplex proportion (essential for gauging the generalizability of findings from multiplex pedigrees). These data may be valuable for planning and interpreting genetic studies of schizophrenia.
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