Linkage Disequilibrium between LDLR rs688 and AvaII Genes and its Significant Association with Ischemic Stroke

Background: To analyze the polymorphism distribution of low density lipoprotein receptor rs688, AvaII, NcoI gene in ischemic stroke, and explore the linkage disequilibrium among them. The correlation between the linkage disequilibrium and ischemic stroke was further analyzed. Methods: The levels of serum lipid (triglyceride, cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A1, apolipoprotein B) and rs688, AvaII, NcoI polymorphism of low density lipoprotein receptor gene were tested in patients with ischemic stroke (n = 140), healthy control (n = 129) and patients with other cerebrovascular diseases (n = 122). Chi-square test was used to compare the gene frequency and allele frequency of each group. Both the linkage disequilibrium of the three genes and the alleles correlated with ischemic stroke were analyzed. The correlation of linkage disequilibrium gene and ischemic stroke was analyzed with logistic binary regression. Results: In the ischemic stroke group, significant difference was observed in frequencies and allelic frequencies of low density lipoprotein receptor (LDLR) rs688 and AvaII. No difference of NcoI was found. Linkage disequilibrium was found for rs688 and AvaII (D’ = 0.927, R2 = 0.509). Allelic genes correlate with ischemic stroke included T of rs688 (X2 = 46.105, p < 0.001) and C of AvaII (X2 = 20.436, p < 0.001). Conclusions: Linkage disequilibrium existed between LDLR rs688 and AvaII genes. With the wild type gene (WT) (rs688/AvaII: CC/TT) as reference, rs688/AvaII: CT/TC, CT/CC and TT/CC increased the risk of ischemic stroke, which might be a genetic marker used for the screen of high-risk population contributing to the prevention of the disease.