We conducted a case-control study to examine the association between the risk of obesity and the exon-8 insertion allele in the UCP2 gene.

The case series included 157 subjects with a body mass index greater than 30 kg/m² (obesity) and no other major disease except for type 2 diabetes; the control series consisted of 150 healthy subjects with a body mass index less than 25 kg/m². In total, 307 subjects between ages 20 and 60 y were screened for the exon-8 insertion allele in the UCP2 gene.

The association between risk of obesity and the UCP2 insertion allele was estimated using multivariate logistic regression. Obesity risk among carriers of the UCP2 insertion allele was slightly higher than among non-carriers (unadjusted odds ratio, 1.42; 95% confidence interval, 0.90 to 2.23); however, when the model was adjusted for sex, age, physical activity, and sedentary lifestyle (hours spent sitting down), a statistically significant odds ratio of obesity (1.94; 95% confidence interval, 1.14 to 3.30; P = 0.01) for carriers of the UCP2 insertion allele was found.

We found a greater risk of developing obesity among individuals carrying the exon-8 insertion allele in the UCP2 gene, independent of sex, age, physical activity, and sedentary lifestyle, which may partly explain some discrepancies found in the literature.