What is the role of genetic susceptibility loci in the development of obesity?

Updated: Jun 09, 2021
  • Author: Osama Hamdy, MD, PhD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Rarely, obesity may be caused by a single gene, but much more commonly it is a complex interplay of susceptibility loci and environmental factors. Genome-wide association studies (GWAS) have found a robust number of genetic susceptibility loci associated with obesity. A single-nucleotide polymorphism (SNP) in the FTO (fat mass and obesity associated) gene and SNPs near the MC4R (melanocortin 4 receptor) gene have been highly associated with BMI. [73, 74, 75, 76]

Although many genetic susceptibility loci have been discovered, the effect sizes of the established loci are small, and combined they explain only a fraction of the variation in BMI between individuals. Their low predictive value means that they have limited value in clinical medicine. [77] Moreover, the fact that increases in the rate of obesity over the last few decades have coincided with changes in dietary habits and activity suggests an important role for environmental factors.

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