Register for BMI in middle age partially determined by genetics
Obesity Genomics and GeneticsOctober 28, 2002
by Maria G. Essig, MS, ELS, senior medical writer - Genetics plays a role in the body mass index (BMI) a person attains in middle age, according to researchers in the U.S.
"Cross-sectional twin and family studies have shown a moderate-to-substantial genetic component for BMI," said Sean A. Coady and colleagues at the National Heart, Lung, and Blood Institute in Maryland and Boston University School of Medicine. "However, the contribution of genetics to the long-term average, variability, or change over time in BMI is less clear."
The investigators analyzed data from the Framingham heart study to develop 380 extended pedigrees involving 1051 age-matched subjects who were followed from the ages of 35 to 55 years. Variance decomposition methods were used to estimate heritability (Genetic variability of adult body mass index: A longitudinal assessment in Framingham families. Obesity Research, 2002;10(7):675-681).
Coady and collaborators discovered that average BMI throughout the adult middle-age years appeared to have moderate heritability (h2=0.37), as did maximum BMI (h2=0.40) and mean residual of body weight (h2=0.36).
In contrast, BMI maximum minus the mean and the standard deviations of BMI and residual of body weight showed weak heritability with h2 values of approximately 0.20. Changes over time in BMI and residual of body weight did not have any genetic component.
"These findings suggest that there is a significant genetic component for the magnitude of BMI throughout an individual's middle-adult years; however, little evidence was found for a genetic contribution to the variability or rate of change in an individual's BMI," said Coady and coauthors.
The corresponding author for this study is Sean A. Coady, National Heart, Lung, and Blood Institute, II Rockledge Center, 6701 Rockledge Drive, MSC: 7934, Bethesda, MD 20892, USA. E-mail: coadys@nih.gov.
A search at www.NewsRx.net using the search term "obesity genomics and genetics" yielded 51 articles in 13 specialized reports.
Key points reported in this study include:
* A moderate genetic component was found for average and maximum body mass index (BMI) values in middle-age individuals
* A moderate genetic component was found for average residual of body weight in middle-age individuals
* A weak genetic influence was found for BMI maximum minus the mean, and the standard deviations of BMI and residual of body weight in middle-age individuals
* No genetic component was found for changes over time in BMI and residual of body weight in this population This article was prepared by Genomics & Genetics Weekly editors from staff and other reports.
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