Association of LOX-1 gene polymorphisms with cerebral infarction in northern Chinese Han population
© Liu et al.; licensee BioMed Central Ltd. 2014
Received: 18 January 2014
Accepted: 20 March 2014
Published: 25 March 2014
Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays an important role in the pathophysiology of atherosclerosis and thrombosis. This study is aimed at evaluating the potential association of 3’-UTR-C188T and G501C in LOX-1 gene with cerebral infarction.
A total of 386 patients with cerebral infarction and 386 healthy controls were included in the study, which were unrelated Chinese Han population in the Liaoning Province of northern China. The single nucleotide polymorphisms, 3’-UTR-C188T and G501C, were analyzed by polymerase chain reaction–ligation detection reaction method.
The frequencies of CC + GC genotype, GC genotype and C allele of G501C in the patients with cerebral infarction were significantly higher than those in the controls (P < 0.01, P < 0.01, P = 0.04, respectively). The correlation still remained after adjusting for confounding risk factors of cerebral infarction. In addition, no significant association was observed between 3’-UTR-C188T and cerebral infarction.
The study indicated that the G501C variant in LOX-1 gene may be associated with susceptibility to cerebral infarction, independent of other common risk factors, in northern Chinese Han population.
KeywordsLOX-1 Ox-LDL Polymorphisms Cerebral infarction Atherosclerosis
Stroke is the second most common cause of death and the leading cause of long-term disability worldwide. In China, with 1.4 billion populations, the annual stroke mortality rate has exceeded heart disease to become the leading cause of death. Additionally, an area of higher stroke incidence exists in the provincial regions of northern China. Cerebral infarction, as the most common type of stroke, accounts for about 43.7% to 78.9% of all strokes in China. Many studies have demonstrated that cerebral infarction is a heterogeneous disease with a complex etiology involving both genetic and environmental contributions[5, 6].
Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a trans-membrane glycoprotein which belongs to a class E scavenger receptor and mediates the uptake and internalization of ox-LDL (oxidized low-density lipoprotein). Recent studies have showed that LOX-1 may play an important role in the pathophysiology of atherosclerosis and thrombosis[8, 9]. Human LOX-1 gene spans over 7000 base pairs and consists of 6 exons and 5 introns and is located on chromosome 12p12-p13. One polymorphism on the 3’-UTR of the LOX-1 gene, 188C-T, has previously been found to be associated with coronary artery disease in Italian and USA population[11–13]. Another polymorphism, a 501G-C transversion, has been found to be associated with myocardial infarction and carotid atherosclerosis[14, 15]. However, up to now, little is known about whether the LOX-1 gene polymorphism is associated with the risk of cerebral infarction or not[16, 17].
Therefore, in the present study, we investigated the association of these two LOX-1 gene polymorphisms (3’-UTR-C188T, G501C) with cerebral infarction in Chinese Han population.
Clinical characteristics of study subjects
62.1 ± 9.89
61.9 ± 9.84
Male gender, n (%)b
25.5 ± 3.25
25.2 ± 3.15
Hypertension, n (%)b
Diabetes, n (%)b
hyperlipidemia, n (%)b
Smoking, n (%)b
Genotype and allele distributions of 3’-UTR-C188T in patients with cerebral infarction and controls
TT + CT vs CC
TT vs CT + CC
Genotype and allele distributions of G501C in patients with cerebral infarction and controls
CC + GC vs GG
CC vs GC + GG
Cerebral infarction risk factors and G501C in the logistic regression analysis
CC + GC vs GG
This study investigated the association between LOX-1 gene polymorphisms, 3’-UTR-C188T and G501C, and cerebral infarction in northern Chinese Han population. In this study, we found that the genotypic and allelic frequencies of G501C were significantly associated with the increased risk of cerebral infarction. However, no association of 3’-UTR-C188T with the risk of cerebral infarction was found.
The 3’-UTR-188 T variant may have effects on transcription at the gene level and affect the exon splicing or the binding affinity of a putative regulatory element. Therefore, the studies on different populations have been performed to uncover whether 3’-UTR-C188T in LOX-1 gene could participate in cardiovascular disease. Mango and Noveli[11, 12] found that there was significant association between 3’-UTR-C188T variant and coronary artery disease in Italian population, indicating that carrier of allele T increased the risk of cardiovascular events, which was consistent to USA population as reported by Chen. Nevertheless, this association has not been replicated in Italian population by Trabetti or Sentinelli[18, 19]. In this study, for the first time, we focus our attention on the association between 3’-UTR-C188T in LOX-1 gene and cerebral infarction. We found that the TT + CT genotype, the TT genotype, the CT genotype and T allele of 3’-UTR-C188T were not associated with the increased risk of cerebral infarction in Chinese Han population.
As for G501C variant in LOX-1 gene, its association with cardiovascular disease is also quite contradictory. Tatsuguchi et al. found the significant association of G501C variant with myocardial infarction in Japanese population, which was opposite to Turkish population as reported by Kurnaz. As for cerebral infarction, Hattori et al. found that the CC + GC genotype and the C allele were not associated with cerebral infarction in Japanese population (P = 0.48, P = 0.91). However, in this study, we found that the CC + GC genotype, the GC genotype and C allele of G501C were significantly associated with the increased risk of cerebral infarction in Chinese Han population. After adjusting for the confounding risk factors, this significant correlation still remained. There are two potential explanations for the divergent results. Genetic heterogeneity may be the important reason. Genotype frequencies of the G501C in our control subjects (71% GG, 25% GC, and 4% CC) are different from those in Japanese population (61% GG, 36% GC, and 3% CC). In addition, the relative small sample size of Hattori’s study, consisting of 235 patients with cerebral infarction and 274 controls, might be more likely to get false negative results.
How can we explain the association between G501C in LOX-1 gene and cerebral infarction in Chinese population? 1) LOX-1 is involved in endothelial activation and dysfunction, monocyte adhesion, the proliferation, migration, and apoptosis of smooth muscle cells, foam cell formation, plaque instability, as well as platelet activation; all of these events are critical in the pathogenesis of atherosclerosis and thrombosis[9, 21]. 2) The G501C polymorphism is a coding region variant identified in the LOX-1 gene, which causes an amino acidic substitution (lysine to asparagine at position 167 in the C-terminal domain). Functional analysis has demonstrated that the substitution reduces ox-LDL binding and uptake in vitro. This nonsynonymous change also alters the ox-LDL -induced LOX-1 expression.
In summary, our study demonstrated that G501C, but not 3’-UTR-C188T, in LOX-1 gene may be associated with susceptibility to cerebral infarction, independent of other common risk factors, in northern Chinese Han population. However, the present study also has some limitations, such as the relative small sample size. Therefore, well-designed studies with large sample sizes regarding the association of LOX-1 gene polymorphisms with cerebral infarction on different ethnic population will be needed to verify these findings in the future.
The present study included 386 cerebral infarction patients and 386 healthy controls, which were unrelated Chinese Han population in the Liaoning Province of northern China. The patients were consecutively hospitalized in the Department of Neurology, the First Affiliated Hospital of China Medical University between September 2011 and December 2012. Eligible patients were defined as those who were first diagnosed with acute cerebral infarction according to neurological examination and radiological imaging. According to TOAST classification, cerebral infarction can be divided into five subtypes: 1) large-artery atherosclerosis (LAA), 2) small-vessel occlusion (SVO), 3) cardioembolism (CE), 4) stroke of other determined etiology, and 5) stroke of undetermined etiology. Patients with LAA and SVO, two most common subtypes of cerebral infarction, were included while other subtypes were excluded. Patients with transient ischemic attack, cerebral trauma, cerebrovascular malformations, coagulation disorders, autoimmune diseases, tumors, and chronic infection diseases were all intentionally excluded from this study. The controls were recruited from the health examination department of the Red Cross Hospital, matched by sex and age, without clinical or radiological evidence of stroke and other neurological diseases. This study was performed according to Declaration of Helsinki and the standards established by the Ethics Committees of both hospitals. The Ethics Committees of both hospitals reviewed and approved the study protocol, and written informed consents for the study were obtained from all participants.
Clinical records of patients and controls, including the general condition, past history, blood pressure, fasting blood glucose, serum triglyceride, and total cholesterol, were collected. For patients, brain CT or MRI, echocardiography, carotid ultrasound, transcranial Doppler, and electrocardiogram were also required. Hyperlipidemia was defined as a total plasma cholesterol level >5.72 mmol/L and/or plasma triglycerides level >1.7 mmol/L, or current use of lipid-lowering drugs.
DNA Extraction and Genotyping
Primer sequences of 3’-UTR-C188T and G501C
Forward: 5’ TTAGGAGTGTGAGGGGAAGGTGA 3’
Reverse: 5’ CCTTTGCAGAAACTGGGGTTCC 3’
Forward: 5’ TGTCCGTCCAAGGTCATACACAA 3’
Reverse: 5’ CCTTGTCCGCAAGACTGGATCT 3’
The probes for LDR
The probe for LDR
Continuous variables were presented as mean ± SD and categorical variables as percentages. Normality of the sample distribution of each continuous variable was tested with the Kolmogorov-Smirnov test. Differences of continuous variables were evaluated by the Student's t or Mann–Whitney U test, depending on the shape of the distribution curves. Categorical variables were compared by χ2 test. Differences of the distributions of alleles and genotypes between cases and controls were analyzed using χ2 test. All genotype frequencies were checked for Hardy-Weinberg analysis in two groups through χ2 test. The association of the LOX-1 gene polymorphisms with cerebral infarction was estimated by computing the odds ratios (OR) and 95% confidence intervals (CI) from binary logistic regression analysis with backward stepwise method. Furthermore, Hosmer-Lemeshow test was used to evaluate the goodness-of-fit of the logistic regression model. A P value of 0.05 was considered statistically significant for all statistical analyses. All the statistical analyses were carried out using SPSS version 17.0 (SPSS, Chicago, IL, USA).
Lectin-like oxidized low-density lipoprotein receptor-1
Oxidized low-density lipoprotein
Polymerase chain reaction-ligation detection reaction
Body mass index.
This study was supported by a grant from the National Natural Science Foundation of China (No. 81070913). We appreciate all subjects who participated in this study.
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