Objective: Twin studies are useful for investigating the causes of trait variation between as well as within a population. The goals of the present study were two-fold: First, we aimed to compare the total phenotypic, genetic and environmental variances of height, weight and BMI between Caucasians and East Asians using twins. Secondly, we intended to estimate the extent to which genetic and environmental factors contribute to differences in variability of height, weight and BMI between Caucasians and East Asians. Design: Height and weight data from 3735 Caucasian and 1584 East Asian twin pairs (age: 13-15 years) from Australia, China, Finland, Japan, the Netherlands, South Korea, Taiwan and the United States were used for analyses. Maximum likelihood twin correlations and variance components model-fitting analyses were conducted to fulfill the goals of the present study. Results: The absolute genetic variances for height, weight and BMI were consistently greater in Caucasians than in East Asians with corresponding differences in total variances for all three body measures. In all 80 to 100% of the differences in total variances of height, weight and BMI between the two population groups were associated with genetic differences. Conclusion: Height, weight and BMI were more variable in Caucasian than in East Asian adolescents. Genetic variances for these three body measures were also larger in Caucasians than in East Asians. Variance components model-fitting analyses indicated that genetic factors contributed to the difference in variability of height, weight and BMI between the two population groups. Association studies for these body measures should take account of our findings of differences in genetic variances between the two population groups.
Bibliographical noteFunding Information:
The South Korean Twin Registry has been supported by the Pioneer Fund, New York. The Finnish Twin Study is a part of the Academy of Finland Centre of Excellence in Complex Disease Genetics. The Finnish Twin Studies have been supported by the National Institute of Alcohol Abuse and Alcoholism (Grants AA-12502, AA-00145 and AA-09203 to RJR) and the Academy of Finland (Grants 100499, and 205585 to JK). The Minnesota Twin Family Study has been supported by the US National Institute of Health Grants, DA13240, DA05147 and AA09367. The Netherlands Twin Registry has been supported by NWO/SPI 56-464-14192, NWO 480-04-004, NWO/VENI 451-04-034 and NWO/Bilateral Agreement 463-06-001. Australian twin data collection was funded by ARC Grants (A79600334, A79906588, A79801419, DP0212016, DP0343921). The Guangzhou Twin Eye Studies have been supported by National Natural Science Foundation of China 30772393, Program for New Century Excellent Talents in University, National Ministry of Education NCET-06-0720, and Guangzhou Science and Technology Development Fund 2006Z3-E0061. Funding resource for the Japanese Twin Studies are Brain Science and Education Program (II), RISTEX, JST. In addition, we acknowledge NIMH Grant MH20030 awarded to Karen Mitchell (PI: Michael Neale) and NIH Grant EY-12562 awarded to Stacey Cherny.
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