The effects of uncoupling protein-1 genotype on lipoprotein cholesterol level in Korean obese subjects

Uncoupling protein-1 (UCP-1) plays a major role in thermogenesis, and has been implicated in the pathogenesis of obesity and metabolic disorders. The purpose of this study was to estimate the effects of A-3826G polymorphism of the UCP-1 gene on the plasma lipid profiles in 190 Korean obese subjects with a body mass index (BMI) more than 30 kg/m2. Height, weight, BMI, wait-to-hip ratio (WHR), obesity index, and body composition were measured and genotype of UCP-1 was analyzed by polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) method. Serum concentrations of fasting glucose, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride were measured. The frequencies of UCP-1 genotypes were AA type, 22.1%; AG type, 53.7%; and GG type, 24.2%; and the frequency of G allele was 0.51. Among many parameters, diastolic blood pressure (DBP) (P = .023) and low-density lipoprotein (LDL) cholesterol (P = .011) were significantly higher in AG and GG types compared with AA type, whereas HDL cholesterol was significantly lower in GG type compared with other types (P < .05). Atherogenic index was significantly higher in GG type compared with AA type (P = 0.027). LDL-to-HDL cholesterol ratio was significantly increased in the order of AA < AG < GG types (P = .001). When the subjects were divided into a normal group and a hyper-LDL cholesterolemia group by LDL cholesterol level of 3.626 mmol/L (140 mg/dL), the frequency of hyper-LDL cholesterolemia was significantly higher in GG type compared with other types by Fisher's exact (chi-square) test (P = .05). When logistic regression analysis was conducted to find the risk factors of hyper-LDL cholesterolemia, the odds ratio was 4.115 (P = .03) for GG type of UCP-1 gene. These results suggest that the GG type of the UCP-1 gene has a strong association with increased LDL cholesterol level and might be a significant risk factor for hyper-LDL cholesterolemia among Korean obese subjects.