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Loos, Ruth J F/0000-0002-8532-5087; Fagnani, Corrado/0000-0001-5771-7772; Busjahn, Andreas/0000-0001-9650-6919; Skytthe, Axel E/0000-0002-8629-4913; Craig, Jeffrey M/0000-0003-3979-7849; Knafo-Noam, Ariel/0000-0003-0613-1960; Kandler, Christian/0000-0002-9175-235X; Christensen, Kaare/0000-0002-5429-5292; Kaprio, Jaakko/0000-0002-3716-2455; Kyvik, Kirsten O/0000-0003-2981-0245; Siribaddana, Sisira/0000-0001-5821-2557; Montgomery, Grant W/0000-0002-4140-8139; Ordonana, Juan R./0000-0001-7779-6017; Colodro-Conde, Lucia/0000-0002-9004-364X; Huibregtse, Brooke M./0000-0003-0977-7249; ONCEL, Sevgi YURT/0000-0002-0990-292X; Duncan, Glen/0000-0001-6909-1869; Magnusson, Patrik/0000-0002-7315-7899; Heikkila, Kauko/0000-0002-9256-8028; mangino, massimo/0000-0002-2167-7470; Medland, Sarah E/0000-0003-1382-380X; Aliev, Fazil/0000-0001-8357-4699; Tan, Qihua/0000-0003-3194-0030; ROMERA, JUAN FRANCISCO SANCHEZ/0000-0002-5405-6216; Sund, Reijo/0000-0002-6268-8117; D'Ippolito, Cristina/0000-0001-7902-9380; Haworth, Claire/0000-0002-8608-289X; Tan, Qihua/0000-0003-3194-0030; Bartels, Meike/0000-0002-9667-7555; Aaltonen, Sari/0000-0002-2873-4263; Sodemann, Morten/0000-0001-8992-2500; Rebato, Esther/0000-0003-1221-8501; van Beijsterveldt, Toos/0000-0002-6617-4201; McAdams, Tom/0000-0002-6825-3499; Llewellyn, Clare/0000-0002-0066-2827; Franz, Carol/0000-0002-8987-1755; Boivin, Michel/0000-0001-8621-9844; Hotopf, Matthew/0000-0002-3980-4466; Kremen, William/0000-0002-8629-5609; Plomin, Robert/0000-0002-0756-3629; Harden, Kathryn/0000-0002-1557-6737; Rasmussen, Finn/0000-0001-7915-7809; Willemsen, Gonneke/0000-0003-3755-0236; Derom, Catherine/0000-0001-5574-796X; Pahlen, Shandell/0000-0003-0753-4155; Silventoinen, Karri/0000-0003-1759-3079; Rijsdijk, Fruhling/0000-0003-4762-2803; Saffery, Richard/0000-0002-9510-4181 WOS: 000361660800008 PubMed: 26337138 A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m(2) in childhood and adolescence and up to 0.2 kg/m(2) in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes. National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; National Institute on AgingUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1RO1-AG13662-01A2]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R21 AG039572]; WT Grant Foundation; University of London Central Research fund; Medical Research CouncilMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research FellowshipLeverhulme Trust [RF/2/RFG/2008/0145]; Goldsmiths, University of London; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; Cooperative Studies Program of the Office of Research & Development of the US Department of Veterans AffairsUS Department of Veterans Affairs; Centre of Research Excellence from the National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [grant ID 1079102]; Michigan State University; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; The National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [1R01ESO15150-01, R01 HD068435, R01 MH062375]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Australian National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children [032-2007]; Victorian Government's Operational Infrastructure Support Program; ENGAGE-European Network for Genetic and Genomic Epidemiology; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Academy of FinlandAcademy of Finland [100499, 205585, 118555, 141054, 265240, 263278, 264146]; Osaka University's International Joint Research Promotion Program; Kirikkale University Research Grant: KKUKirikkale University [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; European Research Council (ERC)European Research Council (ERC) [240994]; European Union's Seventh Framework Programme ENGAGE ConsortiumEuropean Union (EU) [HEALTH-F4-2007- 201413]; European Union's Seventh Framework Programme BioSHaRE EUEuropean Union (EU) [HEALTH-F4-2010-261433]; Seneca FoundationFundacion Seneca; Regional Agency for Science and Technology, Murcia, Spain [08633/PHCS/08, 15302/PHCS/10]; Ministry of Science and Innovation, SpainSpanish Government [PSI11560-2009]; UK Medical Research CouncilMedical Research Council UK (MRC) [G0901245]; UK Biotechnology and Biological Sciences Research CouncilBiotechnology and Biological Sciences Research Council (BBSRC) [31/D19086]; Portuguese agency for research (The Foundation for Science and Technology [FCT] [POCI/DES/56834/2004]; Wellcome TrustWellcome Trust; European Community's Seventh Framework ProgrammeEuropean Union (EU); National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London; Netherlands Organization for Scientific Research (NWO)Netherlands Organization for Scientific Research (NWO); MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; VU University's Institute for Health and Care Research (EMGO+); ERCEuropean Research Council (ERC) [ERC-230374]; Avera Institute, Sioux Falls, South Dakota (USA); Cancer Research UKCancer Research UK [C1418/A7974]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; Fonds Quebecois de la Recherche sur la Societe et la CultureFQRNT; Fonds de la Recherche en Sante du QuebecFonds de la Recherche en Sante du Quebec; Social Science and Humanities Research Council of Canada; National Health Research Development Program; Canadian Institutes for Health ResearchCanadian Institutes of Health Research (CIHR); Sainte-Justine Hospital's Research Center; Canada Research Chair ProgramCanada Research Chairs; [FP7-HEALTH-F4-2007]; [201413]; [NIH RC2 HL103416]; Cancer Research UKCancer Research UK [14133]; Medical Research CouncilMedical Research Council UK (MRC) [G0901245, G9817803B]; NNF Center for Basic Metabolic ResearchNovo Nordisk Foundation [Metabolic Genetics]; Novo Nordisk FondenNovo NordiskNovo Nordisk Foundation [NNF10CC1016515] This study was conducted within the CODATwins project (Academy of Finland #266592). Support for participating twin projects: The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health (grant No. R21 AG039572). Waves 1-3 of Genesis 12-19 were funded by the WT Grant Foundation, the University of London Central Research fund, and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social Research Council (RES-000-22-2206) and the Institute of Social Psychiatry (06/07-11) to Alice M. Gregory, who was also supported at that time by a Leverhulme Research Fellowship (RF/2/RFG/2008/0145). Wave 5 was supported by funding to Alice M. Gregory from Goldsmiths, University of London. Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation, and the US National Institute of Health (P01 AG08761). Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Colorado Twin Registry is funded by NIDA center grant DA011015, and Longitudinal Twin Study HD10333. Author Brooke M. Huibregtse is supported by 5T32DA017637-10. Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381, and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the US Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of NIA/NIH, or VA. The Australian Twin Registry is supported by the Centre of Research Excellence (grant ID 1079102) from the National Health and Medical Research Council administered by the University of Melbourne. The Michigan State University Twin Registry has been supported by Michigan State University as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, and R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of NIMH, NICHD, or the National Institutes of Health.; California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, and 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China (grant #81125007). PETS was supported by grants from the Australian National Health and Medical Research Council (grant Nos. 437015 and 607358 to Jeffrey M Craig, and Richard Saffery), the Bonnie Babes Foundation (grant No. BBF20704 to Jeffrey M. Craig), the Financial Markets Foundation for Children (grant No. 032-2007 to Jeffrey M. Craig), and by the Victorian Government's Operational Infrastructure Support Program. Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement No. 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant Nos. 213506 and 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278, and 264146 to J Kaprio). K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. S.Y. Oncel and F. Aliev are supported by Kirikkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. Longitudinal Israeli Study of Twins was funded by the Starting grant No. 240994 from the European Research Council (ERC) to Ariel Knafo. Data collection and research stemming from the Norwegian Twin Registry is supported, in part, by the European Union's Seventh Framework Programmes ENGAGE Consortium (grant agreement HEALTH-F4-2007- 201413, and BioSHaRE EU (grant agreement HEALTH-F4-2010-261433). The Murcia Twin Registry is supported by the Seneca Foundation, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08 and 15302/PHCS/10) and Ministry of Science and Innovation, Spain (PSI11560-2009). The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council, and the work on obesity in TEDS is supported, in part, by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study project reference: POCI/DES/56834/2004 founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). The Boston University Twin Project is funded by grants (Nos. R01 HD068435 and R01 MH062375) from the National Institutes of Health to K. Saudino. TwinsUK was funded by the Wellcome Trust; European Community's Seventh Framework Programme (FP7/2007-2013). The study also receives support from the National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. University of Washington Twin Registry was supported by the grant NIH RC2 HL103416 (D. Buchwald, PI).; Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192, VU University's Institute for Health and Care Research (EMGO+), the ERC (ERC-230374), and the Avera Institute, Sioux Falls, South Dakota (USA). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant No. 15H05105) from the Japan Society for the Promotion of Science. The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin).

Magnusson, Patrik/0000-0002-7315-7899; Christensen, Kaare/0000-0002-5429-5292; Montgomery, Grant W/0000-0002-4140-8139; Fagnani, Corrado/0000-0001-5771-7772; ROMERA, JUAN FRANCISCO SANCHEZ/0000-0002-5405-6216; Siribaddana, Sisira/0000-0001-5821-2557; Tan, Qihua/0000-0003-3194-0030; Busjahn, Andreas/0000-0001-9650-6919; Tan, Qihua/0000-0003-3194-0030; Ordonana, Juan R./0000-0001-7779-6017; Sund, Reijo/0000-0002-6268-8117; Hjelmborg, Jacob/0000-0001-9630-9149; ONCEL, Sevgi YURT/0000-0002-0990-292X; Colodro-Conde, Lucia/0000-0002-9004-364X; Kandler, Christian/0000-0002-9175-235X; McAdams, Tom/0000-0002-6825-3499; mangino, massimo/0000-0002-2167-7470; Huibregtse, Brooke M./0000-0003-0977-7249; Aliev, Fazil/0000-0001-8357-4699; Kaprio, Jaakko/0000-0002-3716-2455; Skytthe, Axel E/0000-0002-8629-4913; Loos, Ruth J F/0000-0002-8532-5087; Pietilainen, Kirsi/0000-0002-8522-1288; Aaltonen, Sari/0000-0002-2873-4263; Pahlen, Shandell/0000-0003-0753-4155; Rasmussen, Finn/0000-0001-7915-7809; van Beijsterveldt, Toos/0000-0002-6617-4201; Franz, Carol/0000-0002-8987-1755; Bartels, Meike/0000-0002-9667-7555; Kyvik, Kirsten Ohm/0000-0003-2981-0245; Willemsen, Gonneke/0000-0003-3755-0236; Pedersen, Nancy/0000-0001-8057-3543; Silventoinen, Karri/0000-0003-1759-3079 WOS: 000406672300007 PubMed: 28679550 Background: Genes and the environment contribute to variation in adult body mass index [BMI (in kg/m(2))], but factors modifying these variance components are poorly understood. Objective: We analyzed genetic and environmental variation in BMI between men and women from young adulthood to old age from the 1940s to the 2000s and between cultural-geographic regions representing high (North America and Australia), moderate (Europe), and low (East Asia) prevalence of obesity. Design: We used genetic structural equation modeling to analyze BMI in twins >= 20 y of age from 40 cohorts representing 20 countries (140,379 complete twin pairs). Results: The heritability of BMI decreased from 0.77 (95% CI: 0.77, 0.78) and 0.75 (95% CI: 0.74, 0.75) in men and women 2029 y of age to 0.57 (95% CI: 0.54, 0.60) and 0.59 (95% CI: 0.53, 0.65) in men 70-79 y of age and women 80 y of age, respectively. The relative influence of unique environmental factors correspondingly increased. Differences in the sets of genes affecting BMI in men and women increased from 20-29 to 60-69 y of age. Mean BMI and variances in BMI increased from the 1940s to the 2000s and were greatest in North America and Australia, followed by Europe and East Asia. However, heritability estimates were largely similar over measurement years and between regions. There was no evidence of environmental factors shared by co-twins affecting BMI. Conclusions: The heritability of BMI decreased and differences in the sets of genes affecting BMI in men and women increased from young adulthood to old age. The heritability of BMI was largely similar between cultural-geographic regions and measurement years, despite large differences in mean BMI and variances in BMI. Our results show a strong influence of genetic factors on BMI, especially in early adulthood, regardless of the obesity level in the population. Medical Research CouncilMedical Research Council UK (MRC) [G120/635]; NIA NIH HHSUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [P30 AG017265, R01 AG018384]; NIDA NIH HHSUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [T32 DA017637]; NIDDK NIH HHSUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) [P30 DK020541]

Background. A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used. Methodology. Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, the Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents). Principal Findings. Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males). Conclusions. Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments. Background. A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used. Methodology. Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, the Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents). Principal Findings. Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males). Conclusions. Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments. Background. A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used. Methodology. Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, the Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents). Principal Findings. Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males). Conclusions. Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments.

Ved familiær multipel sklerose (MS) forekommer der et øget antal MS-tilfælde i en familie i forhold til for- ventet. Der findes ingen præcis definition af familiær MS, men i de fleste studier inkluderer man familie- medlemmer op til tredje led fra probanden. Op til 20% af alle MS-tilfælde er familiære [1]. Dette er yderst relevant i den kliniske dagligdag, da patienter med MS og deres familiemedlemmer ofte er bekym- rede for, om der hos flere i familien udvikles MS. Den genetiske baggrund for den øgede tilbøjelighed for at udvikle MS er kompleks (Figur 1) og følger ikke en mendelsk arvegang, hvilket tydeligt ses på stamtræet (Figur 2). I tvillingestudier har man påvist en kon- kordansrate for monozygote tvillinger (MZ) på min- dre en 100%, men samtidig en væsentlig højere konkordansrate for MZ- end for dizygote (DZ)-par, hvilket tyder på, at genetik spiller en rolle, men at MS er multifaktoriel.I denne artikel gennemgås, hvad man i dag ved om familiær MS, og det beskrives, hvordan MS- familier og isolerede befolkningsgrupper kan bidrage til øget genetisk viden om MS.

INTRODUCTION: The field of medical studies is rich in stereotypical conceptions of the practitioners of the various medical specialisations.METHOD: By means of a Kahoot of 25 questions about practitioners of nine different medical specialisations, we were trying to see, if a group of people from the medical field (n = 20) and a control group of librarians (n = 22) would answer the questions correctly. The questions were jokes about various medical specialisations, and people were supposed to guess, which kind of medical doctor they described.RESULTS: Those with a background in medical studies were faster and more precise than the librarians. Some of the stereotypes described by the jokes, were known to both groups, others were not. The most familiar stereotypes were those describing anaesthesiologists as sleepy and psychiatrists as crazy. It appeared, that many of the medical speciality stereotypes took their point of departure in the idea, that doctors resemble their patients.CONCLUSION: The survey has limited data, and therefore the conclusion is not very wide-reaching. Some stereotypes were familiar to both groups, others were not. The data indicate that in some cases, contradictory stereotypes exist about individual specialisations.

BackgroundWe wished to establish whether the occurrence of schizophrenia among twins is the same as among the general population.MethodThrough record linkage between the New Danish Twin Register and the Danish Psychiatric Case Register, the twins who have ever received a diagnosis of schizophrenia were identified. Through indirect standardisation for age, sex and dates of admission, the rate of first admission with diagnosis schizophrenia among twins is compared to the same rate in the general population.ResultsA 28% increase in the rate of first admissions for schizophrenia in twins compared to the general population was found. This is statistically significant and does not seem to be caused by any known methodological problems. Twins also had an increased first-admission rate of any psychiatric disorders.ConclusionThis increased risk does not seem to be explained by known methodological problems, but does differ from earlier studies.

To provide contemporary figures of the incidence of childhood onset diabetes mellitus in Denmark, a prospective routine registration system has been established. The present study covered the population of children aged 0-14 years in four Danish counties, observed during the calendar years 1989 through 1993 concerning new cases of the disease. A total of 201 cases (113 boys and 88 girls) were registered, corresponding with a sex- and age-adjusted incidence rate of 17.4 per 100,000 person-years. Based on a validation analysis the study material is considered virtually complete. Overall, the incidence among boys was slightly higher than among girls, but not statistically significantly so. The incidence rate increased with age for both boys and girls. The results confirm that the incidence of childhood onset diabetes in Denmark is relatively high. Compared with previous Danish studies there has been an increase of about 20-25% in the incidence during the last 20 years. Our study stresses the importance of a continuous registration of new cases of childhood diabetes in Denmark, thereby providing clues for further aetiological studies as well as providing reference values for the planning of the diabetes health care. Our results indicate that at least two independent ascertainment sources must be employed to ensure complete registration in studies that rely upon voluntary registration as the primary reporting source. Udgivelsesdato: 1997-Feb-24

Aims/Hypothesis: This prospective study examined the epidemiology of type 1 diabetes in young adults in Europe. Methods: We ascertained incident cases of type 1 diabetes in the 15 to 28 years (both inclusive) age group throughout Europe over a period of 2 years. Diabetes registries in nine countries, in which incidence rates for type 1 diabetes in the 0 to 14 age group were available, took part. Incidence rates were estimated per 100 0000 person years and standardised for secx and age. Cumulative incidences per 1000 from birth to age 30 were estimated. Heterogeneity between centres was tested with a Poisson regression model. Results: A total of 2112 diabetes cases were ascertained in 1996 and 1997, of which 61.4% were considered to be type 1 diabetes. Completeness of ascertainment varied from 70 to 90%. Standardised incidence varied from 4.8 per 100 000 person years to 13.4 per 100 000 person years. The male-female ratio was estimated to be one or more, and in the 25 to 29 age group 1.5 or more in all countries. Cumulative incidences for males and females indicate that the former exceeds the latter from age 24. In the two centres with highest childhood incidence, this applied already from 14 years of age. Conclusions/interpretation: The incidence of type 1 diabetes in adults is lower than in children and the range of incidence is also reduced, with a less than threefold variation in adults, against an eightfold variation in children. There is a male excess in incidence, especially in the age group 25 to 29 years.

Several twin studies have shown that the heritability of the migraine phenotype is approximately 40-60% [1]. The rest should, therefore, be accounted for by environmental factors. Our understanding of the risk factors of migraine remains limited despite many years of research.

Aims: The genetic and environmental influences on metabolic phenotypeshave been intensively studied by twin modeling in different populations.However, twin studies on secular change in metabolic phenotypes havebeen rare due to high expenses, losses of follow up, and long waiting timein prospective investigations. Based on Chinese twin data collected fromDanish-Chinese collaboration research, we perform twin modeling on 13metabolic phenotypes (total cholesterol; triglyceride; high density lipoprotein(HDL); low density lipoprotein (LDL); urine acid (UA); glucose; weight; bodymass index (BMI); waist and hip circumstance and ratio (WHR); systolicblood pressure (SBP); diastolic blood pressure (DBP)) measured longitudinallyin a period of 7 years in 254 middle aged Chinese twins (126 monozygotic;128 dizygotic twins). Methods: Univariate ACE, ADE models andtheir nested models were fitted to the secular changes in each of the 13phenotypes with best fitting model selected based on model performance.Age and sex were included as covariates in the models to adjust for theireffects on secular trend. Results: Variations in secular change in 3 lipids(total cholesterol; triglyceride; LDL), weight and blood pressure (SBP, DBP)have AE model as the best fitting model with low to moderate (a2: 0.25 -0.46) genetic control. Variations in secular change in the rest of the phenotypeshave CE model as the best fitting model with low to moderate (c2:0.21 - 0.55) control by shared environmental factors. Secular changes inall phenotypes are under moderate to high (e2: 0.45 - 0.79) control by uniqueenvironmental factors. Conclusions: Variations in secular change in the13 metabolic phenotypes show limited genetic control. Our results emphasizethe special importance of unique environment in determining individualchange in metabolic phenotypes in adult Chinese.

INTRODUCTION: Responsible conduct of research is the basis for the credibility of all research. Research misconduct is defined as the fabrication, falsification or plagiarism committed willfully or grossly negligently in the planning, performing or reporting of research. We undertook a survey of knowledge of the attitudes towards and experiences with research misconduct among PhD students in clinical research. METHODS: A questionnaire previously used in Swedish and Norwegian studies was distributed to PhD students (n = 330) affiliated with the Department of Clinical Research or Department of Regional Health Research, University of Southern Denmark. RESULTS: A total of 165 PhD students completed the questionnaire in full or in part, yielding an overall response rate of 50%. 18-34% reported to have heard (within the past year) about researchers who had plagiarised, falsified or fabricated data, or plagiarised publications. None reported this to occur in their own department. Few stated that they had felt under pressure to either falsify data (1%) or present results in a misleading way (3%). However, 22% stated to have felt an unethical pressure (within the past year) regarding the inclusion or order of authors. CONCLUSIONS: Results indicate that, albeit at a low frequency, research misconduct involving PhD students is taking place. Likewise, a high fraction of respondents reported to have been under pressure regarding authorships, which points to questionable research practices in clinical research. FUNDING: not relevant. TRIAL REGISTRATION: not relevant.

Studying the multiplex genetic basis of blood pressure regulation can help with elucidating the etiology of hypertension and related diseases as well as with the development of more efficient prevention and treatment strategies. This study aims at investigating the genetic and environmental backgrounds for blood pressure variation as well as for phenotype correlation between systolic and diastolic blood pressure by fitting bivariate models to Danish and Chinese twins and comparing ethnic difference between the two samples. The Danish sample consists of 756 twin pairs (309 monozygotic or MZ pairs, 447 dizygotic or DZ pairs) and Chinese sample includes a total of 325 pairs of twins (183 MZ twin pairs and 142 DZ twin pairs). Our parameter estimates revealed moderate to high additive genetic and unique environmental influences on both systolic and diastolic blood pressure and on their correlation with an overall pattern of higher genetic regulation in Danish than in Chinese twins while higher contribution by unique environment in Chinese than in Danish twins. The estimated genetic components in blood pressure and in blood pressure correlation could serve to guide new researches aiming at looking for heritable genetic variants that affect systolic and/or diastolic blood pressure. Meanwhile, the estimated high contribution to blood pressure by unique environment suggests that promoting healthy lifestyle could provide an efficient way for the control of hypertension especially in the Chinese population.

Background: Neuromyelitis optica (NMO) is a disease with autoimmune characteristics. A genetic autoimmune dependency for NMO has not been clarified in detail. Objective: To investigate immunogenetic aspects of NMO. Methods: Forty-one patients with NMO and 42 patients with multiple sclerosis (MS) were diagnosed in a population-based Caucasian cohort. HLA DQA1, DQB1, and DRB1 alleles were determined. Polymorphisms in programmed death 1 (PD-1) PD-1.3 G/A and protein tyrosine phosphatase non-receptor 22 (PTPN22) 1858 C/T were genotyped. Results: In the NMO group 15% had other autoimmune disorders and 39% had family occurrence of autoimmunity, comparable to MS. A higher frequency of a family history (17%) of NMO and MS was found in the NMO group ( p Conclusion: Patients with NMO had frequent co-existence of autoimmunity and family occurrence of NMO and MS. The PD-1.3A allele was associated with NMO. The data suggest genetic autoimmune dependency of NMO.

Udgivelsesdato: 1996-Dec BACKGROUND: Population based twin registers represent a valuable tool for genetic epidemiological research, since twin studies aim at separating the effect of genes and environment for complex traits. The Danish Twin Register's history, size, ascertainment and completeness of data, as well as data accessibility and availability are described. RESULTS: The Danish Twin Register comprises 14,051 twin pairs born 1870-1930, representing all twins surviving to age six years, and 20,888 twin pairs born 1953-1982, representing 75% of those born 1953-1967 and 95% of those born 1968-1982. The birth cohorts 1931-1952 og 1983-1993 are being ascertained at the moment. The register is available for research given certain conditions are fulfilled. CONCLUSION: This register will in a few years be the most comprehensive twin register in the world. It is a very valuable Danish research resource.

The aim of this study was to estimate the relative influence of genetic and environmental factors on the aetiology of asthma. The classic twin study design was used to analyse data on self-reported asthma obtained by a questionnaire mailed to 34,076 individuals, aged 12-41 yrs and originating from the Danish Twin Register. The cumulative incidence proportion was 6.2% in the pooled sample. No overall sex or zygosity difference was observed. Substantially higher concordance rate, odds ratio and correlation for asthma were estimated in monozygotic than dizygotic twin pairs. Using biometric modelling, a model including additive genetic and non-shared environmental effects provided the best fit to the data. According to this model, 73% of the variation in liability to asthma was explained by genetic effects. The results emphasize a major genetic component in the aetiology of asthma.

Background: Large population-based genome-wide association studies have identified several multiple sclerosis (MS) genetic risk variants, but the existing missing heritability warrants different strategies. Isolated populations offer an alternative way of searching for rare genetic variants and evaluating the possible role of consanguinity in the development of MS. Studies of consanguinity and MS risk have yielded conflicting results. Objectives: In this study we investigated the role of consanguinity on MS risk in the relatively isolated Faroe Islands, which have a presumed high level of inbreeding. Methods: A total of 29 cases and 28 matched controls were genotyped and assessed for inbreeding coefficients, number of runs of homozygosity (ROH) at different lengths and observed number of homozygotes as measures of relatedness. Parametric and non-parametric statistical models were applied. Results: Both cases and controls exhibited considerable relatedness demonstrated by very high inbreeding coefficients, large number of observed homozygotes and many long ROH. However, apart from the number of ROH ≥ 2.5 mega base pairs, no significant differences between the two groups were observed. Conclusions: Overall, no significant difference between cases and controls were found, indicating that consanguinity in itself does not appear to be an important risk factor for MS in the population of the Faroe Islands.

Background Studies of back pain are typically based on the assumption that symptoms from different parts of the spine are distinctive entities. Recently, however, the assumption that back pain is a site-specific disorder has been challenged, suggesting that localized back pain should be seen as part of a general musculoskeletal syndrome. Objectives To describe and compare the patterns of reporting of pain and consequences of pain in the three spinal regions. Methods In all, 34,902 (74%) twin individuals representative of the general Danish population, aged 20 to 71, participated in a cross-sectional nation-wide survey. Identical questions from the Standardised Nordic Questionnaire for each of the three spinal regions were used for lumbar, mid-back and neck pain respectively: Pain past year, pain ever, radiating pain, and consequences of back pain (care-seeking, reduced physical activities, sick-leave, change of work/work duties and disability pension). The relative prevalence estimates of these variables were compared for the three spinal regions. Results The relative proportions of individuals with pain ever, who also reported to have had pain in the past year varied between 75% and 80%, for the three spinal regions. The proportions of individuals with pain in the past year and for various pain durations were also very similar. Regardless if pain was reported in the lumbar, thoracic or cervical regions, the proportions of individuals reporting radiating pain were equally large. The relative number of consequences was the same across the spinal regions, as were the relative proportions of each these consequences. However, low back pain resulted more often in some kind of consequence compared to the consequences of pain in the neck and mid back. Conclusions Back pain and its consequences share many characteristics and may, at least in a general population, be regarded as the same condition regardless of where the pain happens to manifest itself. However, because some exceptions were noted for the lumbar spine, separate entities for a smaller group of individuals with back pain cannot be ruled out.