Differences in genetic and environmental variation in adult BMI by sex, age, time period, and region: an individual-based pooled analysis of 40 twin cohorts

Karri Silventoinen, Aline Jelenkovic, Reijo Sund, Yoshie Yokoyama, Yoon-Mi Hur, Wendy Cozen, Amie E Hwang, Thomas M Mack, Chika Honda, Fujio Inui, Yoshinori Iwatani, Mikio Watanabe, Rie Tomizawa, Kirsi H Pietiläinen, Aila Rissanen, Sisira H Siribaddana, Matthew Hotopf, Athula Sumathipala, Fruhling Rijsdijk, Qihua Tan, Dongfeng Zhang, Zengchang Pang, Maarit Piirtola, Sari Aaltonen, Sevgi Y Öncel, Fazil Aliev, Esther Rebato, Jacob B Hjelmborg, Kaare Christensen, Axel Skytthe, Kirsten O Kyvik, Judy L Silberg, Lindon J Eaves, Tessa L Cutler, Juan R Ordoñana, Juan F Sánchez-Romera, Lucia Colodro-Conde, Yun-Mi Song, Sarah Yang, Kayoung Lee, Carol E Franz, William S Kremen, Michael J Lyons, Andreas Busjahn, Tracy L Nelson, Keith E Whitfield, Christian Kandler, Kerry L Jang, Margaret Gatz, David A Butler, Maria A Stazi, Corrado Fagnani, Cristina D’Ippolito, Glen E Duncan, Dedra Buchwald, Nicholas G Martin, Sarah E Medland, Grant W Montgomery, Hoe-Uk Jeong, Gary E Swan, Ruth Krasnow, Patrik Ke Magnusson, Nancy L Pedersen, Anna K Dahl Aslan, Tom A McAdams, Thalia C Eley, Alice M Gregory, Per Tynelius, Laura A Baker, Catherine Tuvblad, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Timothy D Spector, Massimo Mangino, Genevieve Lachance, S Alexandra Burt, Kelly L Klump, Jennifer R Harris, Ingunn Brandt, Thomas S Nilsen, Robert F Krueger, Matt McGue, Shandell Pahlen, Robin P Corley, Brooke M Huibregtse, Meike Bartels, Catharina Em van Beijsterveldt, Gonneke Willemsen, Jack H Goldberg, Finn Rasmussen, Adam D Tarnoki, David L Tarnoki, Catherine A Derom, Robert F Vlietinck, Ruth Jf Loos, John L Hopper, Joohon Sung, Hermine H Maes, Eric Turkheimer, Dorret I Boomsma, Thorkild Ia Sørensen, Jaakko Kaprio

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The American Journal of Clinical Nutrition Volume 106, Issue 2

doi: doi.org/10.3945/ajcn.117.153643

Abstract

Background

Genes and the environment contribute to variation in adult body mass index [BMI (in kg/m2)], 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 20–29 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.