Peroxisome Proliferator-activated Receptordelta+294T>C Polymorphism And Serum Lipidlevels In The Guangxi Bai Ku Yao Population

Background and Objective:Peroxisome proliferator-activated receptors (PPARs) are a class of ligand-activated nuclear transcription factor belonging to the nuclear receptor superfamily. PPARδ is a subtype of PPARs, an important regulator of lipid and carbohydrate metabolism, its gene polymorphism is closely related with lipid metabolism disorders, obesity, type2diabetes and coronary heart disease. The association of PPARδ+294T>C polymorphism and serum lipid levels is inconsistent in several previous studies. Bai Ku Yao is an isolated branch of the Yao, and still retains the unique customs such as the special clothing, ethnic endogamy. Therefore, homogeneous population of genetic background is ideal group for gene polymorphism research. In previous epidemiologic studies, we found that the serum lipid levels and the prevalence of hyperlipidemia were lower in Bai Ku Yao than in Han Chinese from the same region. We hypothesized that there may be significant differences in some genetic polymorphisms between the two ethnic groups. The present study was undertaken to detect the association of PPARδ+294T>C(rs2016520) polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.Methods:We selected609Bai Ku Yao participants from two main gathering places, Lihu and Baxu villages of Nandan County, using stratified random cluster sampling method in this study. At the same time, we used the same method to extract573Han participants as a control from the local Han villages. We asked about medical history, family history, occupation, life habits, education level and physical activity with the cardiovascular epidemiology survey methodology, and made a physical examination including blood pressure, weight, height, and waist circumference. Serum lipid levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) A-I (ApoA-I) and ApoB were measured. Genomic DNA was extracted by Benzene-chloroform. Genotyping of the PPAR8+294T>C polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.Results:The levels of TC, HDL-C, ApoA-Ⅰ and ApoB were lower in Bai Ku Yao than in Han (P<0.001for all). The frequency of T and C alleles was77.50%and22.50%i n Bai Ku Yao, and72.43%and27.57%in Han (P<0.01); respectively. The frequency of TT, TC and CC genotypes was60.59%,33.83%and5.53%in Bai Ku Yao, and52.18%,40.50%and7.32%in Han (P<0.05); respectively. The levels of LDL-C, ApoB and the ratio of ApoA-I to ApoB in Bai Ku Yao were different among the three genotypes in females but not in males (P<0.05for all). The subjects with TT and TC genotypes had lower serum LDL-C and ApoB levels and higher the ratio of ApoA-I to ApoB than the CC genotype in females. The levels of TC and ApoB in the total Han population were different among the three genotypes (P<0.05for each). The C allele carriers had higher serum TC and ApoB levels than the C allele noncarriers. When serum lipid levels were analyzed according to sex, the difference in serum TC levels in Han was significant in males (P<0.01) but not in females, whereas the difference in serum ApoB levels was significant in females (P<0.05) but not in males. Serum TC and ApoB levels were correlated with genotypes in Han (P <0.05for each) but not in Bai Ku Yao. Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, cigarette smoking, and blood pressure in both ethnic groups.Conclusions:1. There were significant difference in the allelic and genotypic frequencies of PPARδ+294T>C polymorphism between Bai Ku Yao and Han populations. The frequency of PPARδ+294C allele was lower in Bai Ku Yao than in Han.2. It is association of PPARδ+294T>C polymorphism and serum TC, HDL-C, LDL-C, ApoA-I and ApoB levels.3. The association of PPARδ+294T>C polymorphism and serum lipid levels is different between the Bai Ku Yao and Han populations. The discrepancy between the two ethnic groups might partly result from different PPARδ+294T>C polymorphism or PPARδ gene-enviromental interactions.