Association Of The Sterol Regulatory Element Binding Protein-2 Gene Polymorphism With Serum Lipid Levels In The Guang Xi Hei Yi Zhuang Population

Objective Sterol regulatory element-binding protein 2(SREBP-2)is an important nuclear transcription factor in the regulation of cellular cholesterol metabolism.Limited data have showed that the SREBP-2 gene polymorphism at the 1784G＞C locus was associated with some lipid parameters,but the results are also controversial.Hei Yi Zhuang is an isolated subgroup of the Zhuang minority in China.We have previously showed that the lipid profiles in Hei Yi Zhuang were different from those in Han Chinese from the same region.We hypothesize that some genetic factors may be involved in determing the serum levels of lipid phenotypes.The aim of this study was to determine the SREBP-2 gene poiymorphism at the 1784G＞C locus and its association with serum lipid levels in the Hei Yi Zhuang and Han populations.Methods A total of 768 subjects of Hei Yi Zhuang and 798 participants of Han Chinese aged 15-89 were surveyed by a stratified randomized cluster sampling.Blood pressure,body height,body weight,serum lipid and apolipoprotein(Apo)levels were measured,and body mass index(BMI)were calculated.Genotyping of the SREBP-2 gene was performed by polymerase chain reaction and restriction fragment length polymorphism,and then confirmed by direct sequencing.Results Serum levels of total cholesterol(TC),triglycerides(TGs), low-density lipoprotein cholesterol(LDL-C)and Apo B were lower in Hei Yi Zhuang than in Han(P＜0.01 for all),whereas the levels of high-density lipoprotein cholesterol(HDL-C)were higher in Hei Yi Zhuang than in Han(P＜0.001).There were no significant differences in the Apo A1 in both ethnic groups(P＞0.05).The frequencies of G and C alleles were 88.9%and 11.1%in Hei Yi Zhuang,and 84.7%and 15.3%in Han(P＜0.001);respectively.The frequencies of GG,GC and CC genotypes were 78.9%,20.1%and 1.0%in Hei Yi Zhuang,and 70.4%,28.6%and 1.0%in Han(P＜0.001);respectively.The frequencies of G allele and GG genotype in Han were.higher in males than in females,or in high TC(≥5.18 mmol/L)subgroup than in normal TC(＜5.18 mmol/L)subgroup(P＜0.01 for all).The levels of HDL-C in Han were higher in GG genotype than in GC/CC genotype(P＜0.05);In normal TC subgroup, the levels of TG in Hei Yi Zhuang were lower in GG genotype than in GC/CC genotype(P＜0.05).In high TC subgroup,the levels of TC,TG,LDL-C and ApoB in Han were lower in GG genotype than in GC/CC genotype(P＜0.05-0.01).There were no significant differences in the remaining serum lipid parameters between GG and GC/CC genotypes in both ethnic groups(P＜0.05 for all).HDL-C levels were correlated with genotype in Han,and ApoB levels were associated with genotype in Hei Yi Zhuang(P＜0.05 for each).Conclusions There were significant differences in genotypic and allelic frequencies of the 1784G＞C polymorphism of SREBP-2 gene between the Hei Yi Zhuang and Han populations.An association between the polymorphism of SREBP-2 gene at the 1784G＞C site and serum TC,TG,LDL-C and Apo B levels in high TC subgroup was observed in the Han but not in the Hei Yi Zhuang populations.The levels of HDL-C in Han were higher in GG genotype than in GC/CC genotype,In normal TC subgroup,the levels of TG in Hei Yi Zhuang were lower in GG genotype than in GC/CC genotype.The lipid profiles in Hei Yi Zhuang and Han populations are modulated by different genetic and environmental factors.