Association between the LIPG polymorphisms and serum lipid levels in the Maonan and Han populations

Abstract

Introduction: The Maonan population is a relatively isolated minority in China. Little is known about endothelial lipase gene (LIPG) single nucleotide polymorphisms (SNPs) and serum lipid levels in the Chinese populations. The present study aimed to detect the association of several LIPG SNPs and environmental factors with serum lipid levels in the Chinese Maonan and Han populations.

Methods: In total, 773 subjects of Maonan ethnicity and 710 participants of Han ethnicity were randomly selected from our previous stratified randomized samples. Genotypes of the LIPG rs2156552, rs4939883 and rs7241918 SNPs were determined by polymerase chain reaction-restriction fragment length polymorphism, and then confirmed by direct sequencing.

Results: The allelic (rs2156552, rs4939883 and rs7241918) and genotypic (rs2156552 and rs4939883) frequencies were different between the two ethnic groups (p < 0.05-0.01). The minor allele carriers had lower apolipoprotein (Apo)A1/ApoB ratio (rs2156552 and rs7241918), high-density lipoprotein cholesterol (HDL-C) and apolipoprotein (Apo)A1 (rs2156552) levels and higher ApoB levels (rs4939883) in the Han population, and lower HDL-C (rs2156552, rs4939883 and rs7241918) levels in the Maonan minority than the minor allele non-carriers (p < 0.0167 after Bonferroni correction). Subgroup analyses according to sex showed that the minor allele carriers had a lower ApoA1/ApoB ratio (rs2156552 and rs7241918) and higher ApoB levels (rs7241918) in Han males, and lower ApoA1 and HDL-C levels in Maonan females than the minor allele non-carriers (p < 0.0167-0.001).

Conclusions: The present study demonstrates the association between the LIPG polymorphsims and serum lipid levels in the two ethnic groups. These associations might have an ethnic- and or/sex-specificity.

Keywords: endothelial lipase; environmental factors; lipids; single nucleotide polymorphism.

Figure 1

The PCR products of the samples and the genotypes of the LIPG SNPs. Lane M is the 100‐bp marker ladder; (A to C) lanes 1–6 are the PCR products: A, rs2156552 SNP (206 bp); B, rs4939883 SNP (427 bp); C, rs7241918 SNP (512 bp); D, genotyping of the rs2156552 SNP: lanes 1 and 2, TT genotype (206 bp); lanes 3 and 4, AA genotype (147 and 59 bp); and lanes 5 and 6, AT genotype (206, 147 and 59 bp); E, genotyping of the rs4939883 SNP: lanes 1, 3 and 6, CC genotype (343 and 84 bp); lanes 2, TT genotype (427 bp); and lanes 4 and 5, CT genotype (427, 343 and 84 bp); F, genotyping of the rs7241918 SNP: lanes 1 and 2, GT genotype (512‐, 416‐ and 96‐bp); lanes 3 and 4, GG genotype (416 and 96 bp); and lanes 5 and 6, TT genotype (512 bp)

Figure 2

A part of the nucleotide sequences of the LIPG SNPs. A, rs2156552 SNP; B, rs4939883 SNP; C, rs7241918 SNP

Figure 3

The genotypic and allelic frequencies of the LIPG SNPs in the Maonan and Han populations. Allele A: rs2156552A, rs4939883C, or rs7241918T; allele B: rs2156552T, rs4939883T, or rs7241918G; genotype AA: rs2156552AA, rs4939883CC, or rs7241918TT; genotype AB: rs2156552AT, rs4939883CT, or rs7241918GT; genotype BB: rs2156552TT, rs4939883TT, or rs7241918GG. ^a p < 0.05; ^b p < 0.01; p _HWE > 0.05 for all

Figure 4

The genotypic and allelic frequencies of the LIPG SNPs between males (M) and famales (F) in the Maonan and Han populations. Allele A: rs2156552A, rs4939883C, or rs7241918T; allele B: rs2156552T, rs4939883T, or rs7241918G; genotype AA: rs2156552AA, rs4939883CC, or rs7241918TT; genotype AB: rs2156552AT, rs4939883CT, or rs7241918GT; genotype BB: rs2156552TT, rs4939883TT, or rs7241918GG. ^a p < 0.05; ^b p < 0.01; p _HWE > 0.05 for all

Figure 5

The LIPG genotypes and serum lipid levels in the Han and Maonan populations. TC, total cholesterol; TG, triglyceride; HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; ApoA1, apolipoprotein A1; ApoB, apolipoprotein B; ApoA1/ApoB, the ratio of apolipoprotein A1 to apolipoprotein B. The value of TG is presented as the median (interquartile range). The difference between the genotypes was determined by the Kruskal–Wallis test. The p‐value was calculated by ANCOVA, using general linear models, and adjusted for age, sex, body mass index, smoking status, alcohol use, glucose and hypertension; p < 0.0167 was considered statistically significant after adjusting by the Bonferroni correction). ^a p < 0.0167; ^b p < 0.001

Figure 6

The LIPG genotypes and serum lipid levels in males and females of the Han and Maonan populations. TC, total cholesterol; TG, triglyceride; HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; ApoA1, apolipoprotein A1; ApoB, apolipoprotein B; ApoA1/ApoB, the ratio of apolipoprotein A1 to apolipoprotein B. The value of TG is presented as the median (interquartile range). The difference between the genotypes was determined by the Kruskal–Wallis test. The p‐value was calculated by ANCOVA, using general linear models, and adjusted for age, sex, body mass index, smoking status, alcohol use, glucose and hypertension; p < 0.0167 was considered statistically significant after adjusting by the Bonferroni correction). ^a p < 0.0167; ^b p < 0.001