Evaluation of single nucleotide polymorphisms of Pro12Ala in peroxisome proliferator-activated receptor-γ and Gly308Ala in tumor necrosis factor-α genes in obese Asian Indians: a population-based study

Abstract

Namita Bhagat1,2, Mukta Agrawal1, Kalpana Luthra3, Naval K Vikram4, Anoop Misra4, Rajeev Gupta21Department of Home Science, University of Rajasthan, Jaipur, Rajasthan, India; 2Department of Medicine, Fortis Escorts Hospital, Jaipur, Rajasthan, India; 3Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India; 4Department of Medicine, All India Institute of Medical Sciences, New Delhi, IndiaBackground: A population-based case control study was performed to determine the associations of Pro12Ala polymorphism in peroxisome proliferator-activated receptor-γ (PPARG) and Gly308Ala polymorphism in tumor necrosis factor-α (TNFA) genes in obese subjects.Patients and methods: Of 1,400 eligible subjects, ≥20 years, we recruited only 1,127. For extreme phenotype case-control design, we evaluated 201 subjects with body mass index (BMI) ≥30 kg/m2 (Group 1) and 143 with BMI <20 kg/m2 (Group 2). Clinical, anthropometric, biochemical, and nutritional details and polymorphisms were estimated.Results: In Group 1, the dietary intake of calories and fats was higher, physical activity was lower, and prevalence of truncal obesity, hypertension, high total cholesterol, low high-density lipoprotein cholesterol, and diabetes was greater than in Group 2. There were no homozygous polymorphisms of either gene. Heterozygous Pro12Ala polymorphism in PPARG was found in 15 (7.5%) subjects in Group 1 and 3 (2.1%) subjects in Group 2 (P = 0.028), and heterozygous Gly308Ala polymorphism in TNFA was found in 19 (9.5%) in Group 1 and 7 (4.9%) in Group 2 (P = 0.115). Presence of heterozygous polymorphism in PPARG and TNFA-predicted obesity with univariate odds ratio ([OR], 95% confidence intervals) of 2.25 (1.32–3.84, P = 0.003) and 1.48 (1.10–1.99, P = 0.009) and with multivariate OR 1.74 (1.03–2.93, P = 0.038) and 1.46 (1.05–2.03, P = 0.024), respectively. The addition of dietary and physical activity variables did not result in significant change.Conclusion: Obese Asian Indians have greater prevalence of heterozygous polymorphisms of Pro12Ala in PPARG and Gly308Ala in TNFA genes.Keywords: obesity, Asian Indian, Pro12Ala polymorphism, diet, urban