| 61. |
- Silventoinen, Karri, et al.
(författare)
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Genetic and environmental variation in educational attainment : an individual-based analysis of 28 twin cohorts
- 2020
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural–geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational attainment at 25 years of age or older. Genetic factors explained the major part of individual differences in educational attainment (heritability: a2 = 0.43; 0.41–0.44), but also environmental variation shared by co-twins was substantial (c2 = 0.31; 0.30–0.33). The proportions of educational variation explained by genetic and shared environmental factors did not differ between Europe, North America and Australia, and East Asia. When restricted to twins 30 years or older to confirm finalized education, the heritability was higher in the older cohorts born in 1900–1949 (a2 = 0.44; 0.41–0.46) than in the later cohorts born in 1950–1989 (a2 = 0.38; 0.36–0.40), with a corresponding lower influence of common environmental factors (c2 = 0.31; 0.29–0.33 and c2 = 0.34; 0.32–0.36, respectively). In conclusion, both genetic and environmental factors shared by co-twins have an important influence on individual differences in educational attainment. The effect of genetic factors on educational attainment has decreased from the cohorts born before to those born after the 1950s.
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| 62. |
- Silventoinen, Karri, et al.
(författare)
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Smoking remains associated with education after controlling for social background and genetic factors in a study of 18 twin cohorts
- 2022
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Ingår i: Scientific Reports. - : Nature Portfolio. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- We tested the causality between education and smoking using the natural experiment of discordant twin pairs allowing to optimally control for background genetic and childhood social factors. Data from 18 cohorts including 10,527 monozygotic (MZ) and same-sex dizygotic (DZ) twin pairs discordant for education and smoking were analyzed by linear fixed effects regression models. Within twin pairs, education levels were lower among the currently smoking than among the never smoking co-twins and this education difference was larger within DZ than MZ pairs. Similarly, education levels were higher among former smoking than among currently smoking co-twins, and this difference was larger within DZ pairs. Our results support the hypothesis of a causal effect of education on both current smoking status and smoking cessation. However, the even greater intra-pair differences within DZ pairs, who share only 50% of their segregating genes, provide evidence that shared genetic factors also contribute to these associations.
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| 63. |
- Silventoinen, Karri, et al.
(författare)
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The CODATwins Project : The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits
- 2015
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Ingår i: Twin Research and Human Genetics. - : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.
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| 64. |
- Skoogh, Johanna, 1975, et al.
(författare)
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Testicular-cancer survivors experience compromised language following chemotherapy: Findings in a Swedish population-based study 3-26 years after treatment.
- 2012
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Ingår i: Acta oncologica. - 0284-186X .- 1651-226X. ; 51:2, s. 185-197
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background. Studies suggest an increased risk for compromised cognitive function among cancer survivors. It is unclear to what extent chemotherapy is the cause and how the dysfunction, when present, affects everyday life. The objective was to study self-reported behaviours that may depend on cognitive function, among testicular-cancer survivors who received various cycles of cisplatin-based chemotherapy by comparing them with those who did not. Material and methods. We identified 1173 eligible men diagnosed with non-seminomatous testicular cancer treated according to the national cancer-care programs SWENOTECA I-IV between 1981 and 2004. During an 18-month qualitative phase we constructed a study-specific questionnaire including questions about specific activities and behaviour in everyday life. Results. We obtained information from 960 of 1173 (82%) testicular-cancer survivors diagnosed on average 11 years previously. The prevalence of "saying similar but incorrect words" at least once a week was 5% among those having received no chemotherapy versus 16% among those having received five or more cycles, giving a prevalence ratio ("relative risk", RR) of 3.3 with a 95% confidence interval of 1.5 to 7.1. The corresponding figure for "saying words in the wrong order" was 3.1 (1.7-5.8), for "difficulties understanding what other people mean" 3.1 (1.3-7.7), for "saying words other than planned" 2.2 (1.1-4.5) and for "difficulties completing sentences" 2.0 (1.0-3.6). The relative risks for those with a low level of education ranged between 4.9 (1.6-14.9) and 15.3 (1.9-120.5). Conclusion. Testicular-cancer survivors in Sweden who have received five or more cycles of cisplatin-based chemotherapy experience an increased incidence of long-term compromised language; the effect is primarily seen among men with a low level of education.
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| 65. |
- Wirdefeldt, Karin, et al.
(författare)
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Complete ascertainment of Parkinson disease in the Swedish Twin Registry
- 2008
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 29:12, s. 1765-1773
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Tidskriftsartikel (refereegranskat)abstract
- This report describes the ascertainment of Parkinson disease (PD) in all individuals aged 50 years or older (49,814 individuals) from the Swedish Twin Registry. In phase one of the study, all twins were screened for PD using telephone interviews, with a response rate of 72.7%. In phase two, twins with suspected PD were re-contacted to exclude anyone from follow-up who reported parkinsonian symptoms due to diseases other than PD. In the third phase, in-person clinical evaluations were completed for twins who were still considered PD suspects after phase two and for a sample of co-twins. During the clinical evaluations, we also collected blood samples and information about a variety of environmental exposures. Overall prevalence rate for PD was 496 per 100,000 individuals. Among the 132 PD cases identified, there were only three concordant twin pairs. In total 7.2% of PD cases reported a first degree relative with PD.
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