Twin Research

Articles

Sex Differences in Heritability of BMI: A Comparative Study of Results from Twin Studies in Eight Countries

Karoline Schousboea1, Gonneke Willemsena2, Kirsten O. Kyvika3, Jakob Mortensena4, Dorret I. Boomsmaa5, Belinda K. Cornesa6, Chayna J. Davisa7, Corrado Fagnania8, Jacob Hjelmborga9, Jaakko Kaprioa10, Marlies de Langea11, Michelle Lucianoa12, Nicholas G. Martina13, Nancy Pedersena14, Kirsi H. Pietiläinena15, Aila Rissanena16, Suoma Saarnia17, Thorkild I.A. Sørensena18, G. Caroline M. van Baala19 and Jennifer R. Harrisa20 c1

a1 The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.

a2 Department of Biological Psychology,Vrije Universiteit Amsterdam,The Netherlands.

a3 The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.

a4 The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.

a5 Department of Biological Psychology,Vrije Universiteit Amsterdam,The Netherlands.

a6 Queensland Institute for Medical Research, Brisbane, Australia.

a7 Karolinska Institute, Stockholm, Sweden.

a8 Italian National Institute of Health, Laboratory of Epidemiology and Biostatistics, Rome, Italy.

a9 The Danish Twin Registry, Epidemiology, Institute of Public Health, University of Southern Denmark, Denmark.

a10 Department of Public Health, University of Helsinki, Finland.

a11 Twin Research Unit, St.Thomas' Hospital, London, UK.

a12 Queensland Institute for Medical Research, Brisbane, Australia.

a13 Queensland Institute for Medical Research, Brisbane, Australia.

a14 Karolinska Institute, Stockholm, Sweden.

a15 Department of Public Health, University of Helsinki, Finland; Obesity Research Unit, Biomedicum Research Institute, Helsinki Univ. Central Hospital, Finland.

a16 Obesity Research Unit, Biomedicum Research Institute, Helsinki Univ. Central Hospital, Finland.

a17 Department of Public Health, University of Helsinki, Finland.

a18 Danish Epidemiology Science Centre, Institute of Preventive Medicine, Copenhagen University Hospital, Denmark.

a19 Department of Biological Psychology,Vrije Universiteit Amsterdam,The Netherlands.

a20 The Norwegian Insitute of Public Health, Division of Epidemiology, Department of Genes and Environment, Oslo, Norway. jennifer.harris@fhi.no

Abstract

Body mass index (BMI), a simple anthropometric measure, is the most frequently used measure of adiposity and has been instrumental in documenting the worldwide increase in the prevalence of obesity witnessed during the last decades. Although this increase in overweight and obesity is thought to be mainly due to environmental changes, i.e., sedentary lifestyles and high caloric diets, consistent evidence from twin studies demonstrates high heritability and the importance of genetic differences for normal variation in BMI. We analysed self-reported data on BMI from approximately 37,000 complete twin pairs (including opposite sex pairs) aged 20–29 and 30–39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects.

Correspondence:

c1 Address for correspondence: Jennifer R. Harris, The Norwegian Insitute of Public Health, Division of Epidemiology, Department of Genes and Environment, Post Box 4404 Nydalen, N-0403 Oslo, Norway.

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