Diabetes 57:1419-1426, 2008 DOI: 10.2337/db07-1466 © 2008 by the American Diabetes Association
Common Variation in the FTO Gene Alters Diabetes-Related Metabolic Traits to the Extent Expected Given Its Effect on BMI
1 Peninsula Medical School, Exeter, U.K Corresponding author: Prof. Timothy M. Frayling, Institute of Biomedical and Clinical Science, Peninsula Medical School, Magdalen Rd., Exeter, EX1 2LU, U.K. E-mail: tim.frayling{at}pms.ac.uk
Abbreviations:
ALT, alanine aminotransferase; BWHHS, British Women's Heart and Health Study; EFSOCH, Exeter Family Study of Childhood Health; GGT,
OBJECTIVE—Common variation in the FTO gene is associated with BMI and type 2 diabetes. Increased BMI is associated with diabetes risk factors, including raised insulin, glucose, and triglycerides. We aimed to test whether FTO genotype is associated with variation in these metabolic traits. RESEARCH DESIGN AND METHODS—We tested the association between FTO genotype and 10 metabolic traits using data from 17,037 white European individuals. We compared the observed effect of FTO genotype on each trait to that expected given the FTO-BMI and BMI-trait associations.
RESULTS—Each copy of the FTO rs9939609 A allele was associated with higher fasting insulin (0.039 SD [95% CI 0.013–0.064]; P = 0.003), glucose (0.024 [0.001–0.048]; P = 0.044), and triglycerides (0.028 [0.003–0.052]; P = 0.025) and lower HDL cholesterol (0.032 [0.008–0.057]; P = 0.009). There was no evidence of these associations when adjusting for BMI. Associations with fasting alanine aminotransferase, CONCLUSIONS—FTO genotype is associated with metabolic traits to an extent entirely consistent with its effect on BMI. Sample sizes of >12,000 individuals were needed to detect associations at P < 0.05. Our findings highlight the importance of using appropriately powered studies to assess the effects of a known diabetes or obesity variant on secondary traits correlated with these conditions.
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