Evidence for gene-nutrient interaction at the PPARgamma locus

Area of Science:

• Genetics
• Nutritional Science
• Metabolic Health

Background:

• Peroxisome proliferator-activated receptor-gamma (PPARgamma) is crucial for insulin resistance and blood pressure regulation.
• PPARgamma mutations are linked to obesity and insulin resistance, but common variants' effects are unclear.
• Dietary fatty acids may influence PPARgamma activity, suggesting a gene-diet interaction.

Purpose of the Study:

• To investigate the influence of the common PPARgamma Pro12Ala polymorphism on BMI and insulin resistance.
• To examine if the dietary polyunsaturated to saturated fat ratio (P:S ratio) modifies the effect of the Pro12Ala polymorphism.

Main Methods:

• Genotyping for the PPARgamma Pro12Ala polymorphism in 592 nondiabetic participants.
• Analyzing the association between the Pro12Ala variant, P:S ratio, BMI, and fasting insulin.
• Statistical analysis adjusted for age and sex, with interaction terms for gene-diet effects.

Main Results:

• No significant difference in BMI or fasting insulin between Pro homozygotes and Ala allele carriers overall.
• Fasting insulin concentration was negatively associated with the P:S ratio.
• A significant interaction between the P:S ratio and Pro12Ala polymorphism affected both BMI and fasting insulin.

Conclusions:

• The effect of the PPARgamma Pro12Ala polymorphism on BMI and insulin is dependent on the dietary P:S ratio.
• Low P:S ratios are associated with higher BMI in Ala carriers, while high P:S ratios show the opposite effect.
• This gene-nutrient interaction highlights the importance of considering dietary factors in studies of common genetic polymorphisms.