Objective: To investigate the relationships between the A-G point mutation at position -3826 bp in the 5' flanking domain of the uncoupling protein 1 (UCP1 A-3826G) and some obesity phenotypes in the Swedish Obese Subjects (SOS) cohorts of obese and non-obese men and women. Previous studies have supported the hypothesis of an association between the UCP1 A-3826G polymorphism and body weight regulation in humans.
Design: Case-control study comparing obese subjects from the SOS registry and a sample of the Swedish general population (body mass index (BMI) <27 kg/m2) with respect to genotype and allele frequencies of the UCP1 A-3826G polymorphism.
Subjects: A total of 985 Swedish subjects including 674 obese (310 Male; 364 Female) and 311 non-obese subjects (54 Male; 257 Female) from the SOS cohorts.
Measurements: DNA was extracted from total blood and genotyped by PCR-RFLP. Obesity-related phenotypes include weight history for SOS obese cohort and current weight, BMI, waist circumference and waist to hip ratio (WHR) for obese and normal weight subjects.
Results: No significant difference in the allelic frequencies between obese and non-obese subjects (0.25 vs 0.24; P = 0.67). In both genders, current weight, BMI, waist circumference, WHR and weight gain over time (either measures of maximal weight ever achieved minus weight at 20 y or current weight minus weight at 20 y) were similar in carriers and non-carriers of the UCP1 A-3826G mutation (P>0.05). Similar results were obtained when the three genotypes were compared.
Conclusions: In contrast to what was found in other populations, the UCP1 A-3826G sequence variation is not associated with obesity-related phenotypes and weight gain over time in subjects from the SOS cohorts.