Association of TaqIB polymorphism in the cholesteryl ester transfer protein gene with serum lipid levels in the Guangxi Hei Yi Zhuang and Han populations

Background: Cholesteryl ester transfer protein (CETP) plays an important role in lipoprotein metabolism. The present study was undertaken to compare the difference in the CETP TaqIB gene polymorphism and its association with serum lipid levels between the Guangxi Hei Yi Zhuang and Han populations. Methods: A total of 758 subjects of Hei Yi Zhuang and 778 participants of Han Chinese were surveyed. Genotyping of the CETP TaqIB was performed using polymerase chain reaction and restriction fragment length polymorphism and then confirmed using direct sequencing. Results: The genotypic and allelic frequencies were significant differences between smokers and nonsmokers, or between hypertensives and normotensives in Hei Yi Zhuang, and between drinkers and nondrinkers in Han. The levels of high-density lipoprotein cholesterol (HDL-C) and apolipoprotein AI in Hei Yi Zhuang but not in Han were higher in B1B2 genotype than in B1B1 genotype (P < 0.01 for each). Higher HDL-C levels in Hei Yi Zhuang were found only in females, nondrinkers, nonsmokers, subjects with a body mass index of 24 kg/m(2) or lesser, or normotensives in B1B2 genotype. Higher HDL-C levels in Han were found only in females in B1B2 genotype and in subjects with a body mass index of 24 kg/m(2) or lesser or normotensives in B2B2 genotype. The levels of HDL-C in B1B1 and B1B2 individuals in both ethnic groups were higher in drinkers than in nondrinkers. Conclusions: There were significant differences in the interactions between the CETP TaqIB genotypes and several environmental factors in the Hei Yi Zhuang and Han populations. The polymorphism predicted differences in HDL-C and ApoAI in the Hei Yi Zhuang but not in the Han Chinese, even after adjustment for confounding variables. This means that the gene may not be truly involved in regulation of high-density lipoprotein metabolism or that there is an ethnic-specific effect.