Abstract
BackgroundThe associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.MethodsSixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.ResultsThe carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16–0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05–0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17–0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14–0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = −0.06, 95% CI = −0.11–0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06–0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07–0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07–0.23, P < 0.01) than the non-carriers.ConclusionsThe rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.
Highlights
The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive
The rs693 polymorphism is significantly associated with higher levels of APOB, TG, total cholesterol (TC) and LDLC, and lower levels of high-density lipoprotein cholesterol (HDL-C)
The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and low-density lipoprotein cholesterol (LDL-C)
Summary
The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. The APOB gene is highly polymorphic, and there are over 5000 polymorphic sites in or around the APOB gene (https:// www.ncbi.nlm.nih.gov/snp/?term=APOB) These polymorphic loci can be divided into single nucleotide polymorphisms (SNPs), insertion/deletion polymorphisms, and small tandem repeat polymorphisms according to the characteristics of nucleotide sequences. Two SNPs (rs693 and rs17240441) within the APOB gene have been extensively studied in respect of their associations with plasma lipid levels and CHD risk over the past three decades. The rs17240441 polymorphism is located in the first exon of the APOB gene [6] It is formed by the insertion/deletion of a nine-nucleotide sequence (GCAGCGCCA) in exon 1, resulting in insertion/deletion of 3 amino acid residues (Arg-Glu-Val) in the signal peptide of APOB. Research results showed that the D allele was a risk allele for CHD [6, 7] and the frequency of the D allele is 0.12–0.39 in Asians, 0.21–0.64 in Caucasians, and 0.23–0.68 in Africans
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