Genetic variability of adult body mass index: a longitudinal assessment in framingham families.
OBJECTIVE
To explore the contribution of genetics to the mean, SD, maximum value, maximum less the mean, and change over time in body mass index (BMI) and the residual of body weight after adjustment for height. BMI is frequently used as a general indicator of obesity because of its ease and reliability in ascertainment. Cross-sectional twin and family studies have shown a moderate-to-substantial genetic component for BMI. However, the contribution of genetics to the long-term average, variability, or change over time in BMI is less clear.


METHODS
Longitudinal data from the Framingham heart study were used to create pedigrees of age-matched individuals. Heritability estimates were derived using variance-decomposition methods on a total of 1051 individuals from 380 extended pedigrees followed for a period of 20 years. All subjects were followed from approximately age 35 to 55 years.


RESULTS
Moderate heritability estimates were found for the mean BMI (h(2) = 0.37), maximum BMI (h(2) = 0.40), and the mean residual of body weight (h(2) = 0.36). Low heritability estimates (h(2) congruent with 0.20) were found for the maximum less the mean in BMI and the SDs of BMI and residual of body weight. No additive genetic contribution was found for the average change over time in BMI or the residual of body weight.


CONCLUSIONS
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.
Coady
Sean A
SA
Division of Epidemiology and Clinical Applications, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA. coadys@nih.gov
Jaquish
Cashell E
CE
Fabsitz
Richard R
RR
Larson
Martin G
MG
Cupples
L Adrienne
LA
Myers
Richard H
RH
D000328:Adult; D015982:Bias; D001827:Body Height / Q000235:genetics; D015992:Body Mass Index; D001835:Body Weight / Q000235:genetics; D005260:Female; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008404:Massachusetts; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology / Q000235:genetics*; D012044:Regression Analysis