Association of Tumor Necrosis Factor-α 308A/G Gene Polymorphism with Obesity among a Population of Southwestern Nigeria

Abstract

Obesity often results from interplay of genetics, nutrition and lifestyle. A polymorphic variant of the Tumor Necrosis Factor-α
(TNF- α) promoter region (308G/A) is associated with increased production of TNF- α protein, which could lead to fat
accumulation implicated in the development of obesity and cardiovascular disease. This study investigated the association of
TNF-α 308G/A polymorphism with obesity among a population residing in Southwestern Nigeria. Two hundred (200) obese
and 197 age and sex matched non-obese subjects were enrolled. Blood pressure, weight, height, waist and hip circumferences
were measured. Estimation of fasting blood sugar level, DNA extraction from whole blood and genotyping of single nucleotide
polymorphisms of TNF-α 308G/A were done using standard laboratory procedures. Data were analyzed and p-value < 0.05
was considered significant. Mean body weight and BMI were significantly increased in the obese group (81.92±1.00 kg,
33.01±0.25kg/m2) compared with controls (72.03±1.01 kg, 22.06±0.22kg/m2). Waist and hip circumferences were increased
among obese subjects (p<0.05). Occurrence of A allele was higher (85.3%) than G allele (68.5%) among participants.
Frequency of AA genotype was 51% (OR: 8.137, CI: 3.882 - 17.060, P=0.01) in obese subject and 11.34% in the non-obese, wild
GG genotype was lower in obese (6%) than non-obese individuals (23.71%). Heterozygous AG occurred more in non-obese
(64%) than obese (43%) subjects. Homozygous AA variant of TNF-α 308 is strongly associated with occurrence of obesity
among the studied population. There was no association between GG variant of TNF-α -308 and obesity