Genetic variants on chromosome 9p21 and ischemic stroke in Chinese

Genetic variations in IKZF3, LET7-a2, and CDKN2B-AS1: Exploring associations with metabolic syndrome susceptibility and clinical manifestations

BACKGROUND AND AIM

Metabolic syndrome (MetS) increases the risk of atherosclerosis and diabetes, but there are no approved predictive markers. This study assessed the role of specific genetic variations in MetS susceptibility and their impact on clinical manifestations.

METHOD

In this study, a genotype-phenotype assessment was performed for IKZF3 (rs907091), microRNA-let-7a-2 (rs1143770), and lncRNA-CDKN2B-AS1 (rs1333045).

RESULTS

Analyses indicate that while rs907091 and rs1143770 may have potential associations with MetS susceptibility and an increased risk of atherosclerosis and diabetes, there is an observed trend suggesting that the rs1333045 CC genotype may be associated with a decreased risk of MetS. The genotypes and allele frequencies of rs1333045 were significantly different between studied groups (OR = 0.56, 95% CI 0.38-0.81, p = 0.002, and OR = 0.71, 95% CI 0.55-0.92, p = 0.008), with the CC genotype displaying increased levels of HDL. Furthermore, the rs907091 TT genotype was associated with increased triglyceride, cholesterol, and HOMA index in MetS patients. Subjects with the CC genotype for rs1143770 had higher HbA1c and BMI. In silico analyses illustrated that rs907091 C remarkably influences the secondary structure and the target site of a broad spectrum of microRNAs, especially hsa-miR-4497. Moreover, rs1333045 creates a binding site for seven different microRNAs.

CONCLUSION

Further studies on other populations may help confirm these SNPs as useful predictive markers in assessing the MetS risk.

Transcriptomic analysis reveals the potential biological mechanism of AIS and lung adenocarcinoma

Introduction

Acute ischemic stroke (AIS) and lung adenocarcinoma (LUAD) are associated with some of the highest morbidity and mortality rates worldwide. Despite reports on their strong correlation, the causal relationship is not fully understood. The study aimed to identify and annotate the biological functions of hub genes with clinical diagnostic efficacy in AIS and LUAD.

Methods

Transcriptome and single-cell datasets were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). We identified the differentially expressed genes (DEGs) upregulated in AIS and LUAD and found 372 genes intersecting both datasets. Hub genes were identified using protein-protein interaction (PPI) networks, and the diagnostic and prognostic utility of these hub genes was then investigated using receiver operating characteristic (ROC) curves, survival analysis, and univariable Cox proportional hazard regression. Single-cell analysis was used to detect whether the hub genes were expressed in tumor epithelial cells. The immune microenvironment of AIS and LUAD was assessed using the CIBERSORT algorithm. The protein expression of these hub genes was tracked using the Human Protein Atlas (HPA). We calculated the number of positive cells using the digital pathology software QuPath. Finally, we performed molecular docking after using the Enrichr database to predict possible medicines.

Results

We identified the molecular mechanisms underlying hub genes in AIS and LUAD and found that CCNA2, CCNB1, CDKN2A, and CDK1 were highly expressed in AIS and LUAD tissue samples compared to controls. The hub genes were mainly involved in the following pathways: the cell cycle, cellular senescence, and the HIF-1 signaling pathway. Using immunohistochemical slices from the HPA database, we confirmed that these hub genes have a high diagnostic capability for AIS and LUAD. Further, their high expression is associated with poor prognosis. Finally, curcumin was tested as a potential medication using molecular docking modeling.

Discussion

Our findings suggest that the hub genes we found in this study contribute to the development and progression of AIS and LUAD by altering the cellular senescence pathway. Thus, they may be promising markers for diagnosis and prognosis.

Effect of 9p21.3 (lncRNA and CDKN2A/2B) variant on lipid profile

Background

Several 9p21.3 variants, such as rs1333049, rs4977574, rs10757274, rs10757278, and rs10811661, identified from recent genome-wide association studies (GWASs) are reported to be associated with coronary artery disease (CAD) susceptibility but independent of dyslipidemia. This study investigated whether these 9p21.3 variants influenced lipid profiles.

Methods and results

By searching the PubMed and Cochrane databases, 101,099 individuals were included in the analysis. The consistent finding for the rs1333049 C allele on lipid profiles increased the triglyceride (TG) levels. Moreover, the rs4977574 G allele and the rs10757274 G allele, respectively, increased low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels. However, the rs10811661 C allele largely reduced LDL-C levels. Subgroup analyses indicated that the effects of the rs1333049 C allele, rs4977574 G allele, and rs10757274 G allele on lipid profiles were stronger in Whites compared with Asians. In contrast, the effect of the rs10811661 C allele on lipid profiles was stronger in Asians compared with Whites.

Conclusion

The rs1333049 C allele, rs4977574 G allele, and rs10757274 G allele of lncRNA, and the rs10811661 G allele of CDKN2A/2B had a significant influence on lipid levels, which may help the understanding of the underlying mechanisms between 9p21.3 variants and CAD.

Association of Single-Nucleotide Polymorphisms of rs2383206, rs2383207, and rs10757278 With Stroke Risk in the Chinese Population: A Meta-analysis

Several studies have reported that chromosome 9p21 is significantly associated with ischemic stroke (IS) risk, with the G allele associated with increased risk. However, controversial results have been reported in the literature. We systematically assessed the relationship between stroke and three 9p21 loci (rs2383206, rs2383207, and rs10757278) in this meta-analysis. First, we searched the PubMed and Embase databases for relevant studies. We then calculated odds ratios using the chi-squared test. The evaluation of experimental data was performed using bias tests and sensitivity analyses. We analyzed data from 16 studies involving 18,584 individuals of Chinese ancestry, including 14,033 cases and 14,656 controls. Our results indicated that chromosome 9p21 is significantly associated with IS (odds ratio: 1.15, 95% confidence interval: 1.1–1.20, p < 0.0001). Because the three single-nucleotide polymorphisms (rs2383206, rs2383207, and 10757278) have a linkage disequilibrium relationship, all three may increase the risk of IS.

Genetic association of ANRIL with susceptibility to Ischemic stroke: A comprehensive meta-analysis

Background

Ischemic stroke (IS) is a complex polygenic disease with a strong genetic background. The relationship between the ANRIL (antisense non-coding RNA in the INK4 locus) in chromosome 9p21 region and IS has been reported across populations worldwide; however, these studies have yielded inconsistent results. The aim of this study is to clarify the types of single-nucleotide polymorphisms on the ANRIL locus associated with susceptibility to IS using meta-analysis and comprehensively assess the strength of the association.

Methods

Relevant studies were identified by comprehensive and systematic literature searches. The quality of each study was assessed using the Newcastle-Ottawa Scale. Allele and genotype frequencies were extracted from each of the included studies. Odds ratios with corresponding 95% confidence intervals of combined analyses were calculated under three genetic models (allele frequency comparison, dominant model, and recessive model) using a random-effects or fixed-effects model. Heterogeneity was tested using the chi-square test based on the Cochran Q statistic and I2 metric, and subgroup analyses and a meta-regression model were used to explore sources of heterogeneity. The correction for multiple testing used the false discovery rate method proposed by Benjamini and Hochberg. The assessment of publication bias employed funnel plots and Egger’s test.

Results

We identified 25 studies (15 SNPs, involving a total of 11,527 cases and 12,216 controls maximum) and performed a meta-analysis. Eight SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1333049, rs1537378, rs4977574, and rs1004638) in ANRIL were significantly associated with IS risk. Six of these SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1537378, and rs4977574) had a significant relationship to the large artery atherosclerosis subtype of IS. Two SNPs (rs2383206 and rs4977574) were associated with IS mainly in Asians, and three SNPs (rs10757274, rs1333040, and rs1333049) were associated with susceptibility to IS mainly in Caucasians. Sensitivity analyses confirmed the reliability of the original results. Ethnicity and individual studies may be the main sources of heterogeneity in ANRIL.

Conclusions

Our results suggest that some single-nucleotide polymorphisms on the ANRIL locus may be associated with IS risk. Future studies with larger sample numbers are necessary to confirm this result. Additional functional analyses of causal effects of these polymorphisms on IS subtypes are also essential.

Association between rs3088440 (G > A) polymorphism at 9p21.3 locus with the occurrence and severity of coronary artery disease in an Iranian population

BACKGROUND

Several genome-wide association studies showed that a series of genetic variants located at the chromosome 9p21 locus are strongly associated with coronary artery disease (CAD).

RATIONALE AND PURPOSE OF THE STUDY

In the present study, the relationship of rs3088440 (G > A) in cyclin-dependent kinase inhibitor 2A (CDKN2A) gene site with the presence of coronary artery disease (CAD) and its severity was evaluated in an Iranian population.

METHODS AND RESULTS

The presence of rs3088440 (G > A) genotypes was assessed by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) technique in 324 CAD patients and 148 normal controls. rs3088440 (G > A) polymorphism was associated with increased risk of CAD in the total population (adjusted OR = 1.76, 95% CI = 1.10-2.82; p-value = 0.017) or in women (adjusted OR = 2.96, 95% CI = 1.34-6.55; p-value = 0.007), but not in the men (adjusted OR = 1.35, 95% CI = 0.70-2.6; p-value = 0.368).

CONCLUSIONS

Our findings suggest that the presence of rs3088440 (G > A) is potentially linked with the risk of CAD and its severity in whole study subjects or in women only, independent of CAD risk factors.

Association of SNPs in CDKN2A (P14ARF) Tumour Suppressor Gene With Endometrial Cancer in Postmenopausal Women

BACKGROUND/AIM

This research was aimed to evaluate the association between three selected single nucleotide polymorphisms (SNPs) within the CDKN2A (P14ARF) tumour suppressor gene and the incidence of endometrial cancer (EC) in postmenopausal women.

PATIENTS AND METHODS

The study included 194 postmenopausal women; 144 with EC and 50 non-cancer controls. Genotypes in P14ARF rs3088440, rs3731217 and rs3731245 polymorphisms were assayed using PCR-RFLP and confirmed by sequencing.

RESULTS

Regarding the rs3088440 polymorphism, CT, and CT-TT genotypes, were more prevalent among EC patients than in controls (OR=5.55, p=0.023, OR=5.29, p=0.027; and OR=2.92, p=0.023, respectively). The T allele within rs3088440 was more prevalent in EC females than in controls (χ²=4.7, p=0.030). Considering rs3731217, TG and TG-GG genotypes were less prevalent among EC (OR=0.34, p=0.024 or p=0.023; and OR=0.38, p=0.035, respectively).

CONCLUSION

Polymorphisms in the CDKN2A gene are associated with EC in postmenopausal women.

Genetic variants on chromosome 9p21 confer risks of cerebral infarction in the Chinese population: a meta-analysis

Ischemic stroke (IS) is the leading cause of disability. Researchers have demonstrated that IS is more a multifactorial disorder than a single-factor disease. At present, no consistent conclusions have been reached on susceptibility loci for IS on chromosome 9p21. We conducted this meta-analysis to verify whether genetic loci on chromosome 9p21 reported domestically and abroad could be responsible for IS in Chinese populations. We analyzed data from eight studies that covered a total of 9756 individuals with Chinese ancestry comprising 4254 cases and 5502 controls. Each of the four reported susceptibility loci (rs2383206, rs2383207, rs10757274, and rs10757278) was analyzed separately. The odds ratios (ORs) of rs2383206 and rs10757274 were 1.09 (95% confidence interval (CI): 1.02–1.06, P = 0.01) and 1.09 (95% CI: 1.01–1.17, P = 0.03), respectively. For rs2383207, OR value was 0.91 (95% CI: 0.84–0.98, P = 0.01). No statistical association was identified for rs10757278. We have verified previous associations for IS in Chinese populations on chromosome 9p21. Loci rs2383206 and rs10757274 may increase susceptibility to IS. Mutation at locus rs2383207 may be beneficial. However, we are unable to identify any association between rs10757278 and IS.

Impact of MDM2, TP53 and P14ARF Polymorphisms on Endometrial Cancer Risk and Onset

BACKGROUND/AIM

The aim of this study was to determine the joint effect of single nucleotide polymorphisms (SNPs) of MDM2, TP53, and CDKN2A (P14ARF) genes on the onset and course of endometrial cancer (EC) in postmenopausal women.

MATERIALS AND METHODS

The study group consisted of 144 EC women and 50 non-cancer controls. MDM2 rs22279744, TP53 rs1042522, and P14ARF rs3088440, rs3731217, and rs3731245 SNPs were analysed.

RESULTS

The double-SNP combinations T-C, T-T, or T-G in MDM2 SNP 309 and P14ARF polymorphisms decreased EC risk. The triple-SNP combinations T-C-T, T-C-G, or T-T-G in MDM2 SNP and two P14ARF polymorphisms decreased EC risk. The multiple-SNP combination T-C-T-G in MDM2 and three P14ARF polymorphisms decreased EC risk. The G-Arg-C-T-G carriers were at increased EC risk, while the T-Arg-C-T-G carriers were at decreased EC risk.

CONCLUSION

MDM2 SNP309 plays a role in EC onset in postmenopausal women.

Effects of ANRIL variants on the risk of ischemic stroke: a meta-analysis

Background: Several studies investigated the relationship between antisense non-coding RNA in the INK4 locus (ANRIL) variants and the risk of ischemic stroke (IS), yet whether ANRIL variants are associated with IS remain controversial. Therefore, we performed the present study to obtain a more conclusive result. Methods: Literature retrieval was conducted in PubMed, Medline and Embase. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Results: Eighteen studies were enrolled for analyses. Pooled overall analyses showed that rs2383206 (recessive model: P=0.002, OR = 1.22, 95%CI 1.08–1.38; allele model: P=0.003, OR = 0.90, 95%CI 0.84–0.96) and rs10757274 (allele model: P=0.006, OR = 0.91, 95%CI 0.86–0.97) variants were significantly associated with an increased risk of IS. Further subgroup analyses by ethnicity revealed that rs2383206, rs10757274 and rs10757278 variants were all significantly correlated with an increased risk of IS in Asians. Additionally, rs10757278 polymorphism was also significantly correlated with an increased risk of IS in Caucasians. Conclusions: Our findings indicated that rs2383206, rs10757274 and rs10757278 variants may impact individual susceptibility to IS in Asians. Moreover, rs10757278 polymorphism may also impact individual susceptibility to IS in Caucasians.

Monogenic, Polygenic, and MicroRNA Markers for Ischemic Stroke

Ischemic stroke (IS) is a leading disease with high mortality and disability, as well as with limited therapeutic window. Biomarkers for earlier diagnosis of IS have long been pursued. Family and twin studies confirm that genetic variations play an important role in IS pathogenesis. Besides DNA mutations found previously by genetic linkage analysis for monogenic IS (Mendelian inheritance), recent studies using genome-wide associated study (GWAS) and microRNA expression profiling have resulted in a large number of DNA and microRNA biomarkers in polygenic IS (sporadic IS), especially in different IS subtypes and imaging phenotypes. The present review summarizes genetic markers discovered by clinical studies and discusses their pathogenic molecular mechanisms involved in developmental or regenerative anomalies of blood vessel walls, neuronal apoptosis, excitotoxic death, inflammation, neurogenesis, and angiogenesis. The possible impact of environment on genetics is addressed as well. We also include a perspective on further studies and clinical application of these IS biomarkers.

Evaluation of the role of CDKN2B gene in type 2 diabetes mellitus and hypertension in ethnic Saudi Arabs

Background

Coronary heart disease (CAD) is a multiple with several contributory risk traits, including type 2 diabetes and hypertension, which may share common genetic risk variants with the disease. Genome-wide association studies (GWASs) have yielded a wealth of information suggesting that CAD, the extent of contributory variants may differ according to genetic locus. The present study aimed at verifying whether the cyclin-dependent kinase 4 inhibitor B (CDKN2B) genomic region strongly associated with coronary artery disease (CAD)/myocardial infarction (MI) may also constitute risk for its risk factors type 2 diabetes mellitus (T2DM) and hypertension (HTN) in ethnic Saudi Arabs.

Methodology

We genotyped eight CDKN2B SNPs for cardiovascular risk in a total of 4650 Saudi Arabs, (3049 male and 1601 female) by Taqman assay. Of these individuals, 3732 had primary hypertension and 2576 had type 2 diabetes mellitus.

Results

Out of the eight studied SNPs, two, rs10757274_A [0.915 (0.840-1.00); p = 0.042], rs1333045_T [0.92(0.84-1.00); p = 0.048] were initially associated with type 2 diabetes but lost the association after multivariate adjustments for CAD, hypertension and MI, while rs10757274_A showed borderline association with hypertension.

Conclusions

Our finding does not support the notion of a critical role for the CDKN2B gene locus as a HTN or T2DM cardiovascular risk in ethnic Arabs. The study also demonstrates the importance of replication studies in ascertaining the role of a genomic sequence in disease.

The role of CDKN2B in cardiovascular risk in ethnic Saudi Arabs: A validation study

BACKGROUND

Genome-wide association studies (GWASs) have yielded a wealth of information furnishing support for the variability in genetic predisposition to disease. However, the actual impact of such findings on any particular ethnic population needs to be validated through replication studies. In the present study, we verified recent findings of a GWAS demonstrating a strong association for the cyclin-dependent kinase 4 inhibitor B (CDKN2B) genomic region with coronary artery disease (CAD)/myocardial infarction (MI) in ethnic Saudi Arabs.

METHODOLOGY

We genotyped 8 CDKN2B SNPs for cardiovascular risk in 4650 Saudi Arabs, comprising 2429 CAD cases (1860 males; 569 female) and 2221 controls (1189 male; 1032 female) by Taqman assay.

RESULTS

Four SNPs, rs4977574_A [0.56(0.50-0.63); p < 0.0001], rs10757274_A [0.87(0.77-0.97); p = 0.014], rs10738607_A [0.89(0.80-1.00); p = 0.043] and rs1333045_T [0.54(0.48-0.61); p < 0.0001] residing on the CDKN2B gene were significantly associated with CAD following multivariate adjustments for MI, HTN and DM, while four others were weakly associated with the disease. Likewise, three SNPs, rs1412829_G [0.84(0.72-0.97); p = 0.019], rs564398_C [0.81(0.70-0.94); p = 0.006], rs4977756_G [0.87(0.76-0.99); p = 0.036] were significantly associated with MI after multivariate adjustments for CAD, HTN and DM, while the other five displayed borderline associations.

CONCLUSIONS

Our findings strongly support the notion of a critical role for the CDKN2B gene locus as a cardiovascular risk in ethnic Arabs. The study also demonstrates the importance of replication studies in ascertaining the role of a genomic sequence in disease.

APOL1, CDKN2A/CDKN2B, and HDAC9 polymorphisms and small vessel ischemic stroke

OBJECTIVE

Worldwide, the highest frequencies of APOL1-associated kidney variants are found in indigenous West Africans among whom small vessel disease (SVD) ischemic stroke is the most common stroke phenotype. The objective of this study was to investigate the association and effect sizes of 23 selected SNPs in 14 genes of relevance, including the APOL1 G1 variants, with the occurrence of SVD ischemic stroke among indigenous West African participants in the Stroke Investigative Research and Education Network (SIREN) Study.

MATERIALS AND METHODS

Cases were consecutively recruited consenting adults (aged 18 years or older) with neuroimaging-confirmed first clinical stroke. Stroke-free controls were ascertained using a locally validated version of the Questionnaire for Verifying Stroke-Free Status (QVSFS). Logistic regression models adjusting for known vascular risk factors were fitted to assess the associations of the 23 SNPs in rigorously phenotyped cases (N = 154) of SVD ischemic stroke and stroke-free (N = 483) controls.

RESULTS

Apolipoprotein L1 (APOL1) rs73885319 (OR = 1.52; CI: 1.09-2.13, P-value = .013), rs2383207 in CDKN2A/CDKN2B (OR = 3.08; CI: 1.15-8.26, P -value = .026) and rs2107595 (OR = 1.70; CI: 1.12-2.60, P-value = .014) and rs28688791 (OR = 1.52; CI: 1.03-2.26, P-value = .036) in HDAC9 gene were associated with SVD stroke at 0.05 significance level. Polymorphisms in other genes did not show significant associations.

CONCLUSION

This is the first report of a specific association of APOL1 with a stroke subtype. Further research is needed to confirm these initial findings and deepen understanding of the genetics of stroke in people of African ancestry with possible implications for other ancestries as all humans originated from Africa.

The research on association of copy number variation in chromosome 9p21 region with atherothrombotic stroke in the Han Chinese population

BACKGROUND/PURPOSE

The copy number variants (CNVs) contain more genetic information compared with SNPs. The aim of this study was to elucidate whether the CNVs in Chromosome 9p21 region are associated with increased risk of Atherothrombotic stroke (ATS) in a Han Chinese population.

METHODS

A case-controlled association study was conducted in which only patients with ATS were enrolled. The CNVs were detected by the method of multiplex competitive amplification. The differences in distribution of CNVs between cases and controls were analyzed using univariate and multivariate logistic regression analysis. Subgroup analyses were also carried out to determine whether the effect of the CNVs was specific to age and gender among the subjects.

RESULTS

A total of 274 ATS patients and 282 health controls were included in the present study. 4 genes (ANRIL, CDKN2A, CDKN2B, and MTAP) including eight gene fragments in all were analyzed for CNV. The results showed that the copied number of most CNV in the 4 genes is two. There was no significant difference of CNV frequency between groups.

CONCLUSIONS

The obtained data suggested a negative association between CNV of the four genes and ATS. It is necessary to perform sequencing analyses across the entire 9p21 region for detecting rare or uncommon CNV.

Polymorphisms in the long non-coding RNA CDKN2B-AS1 may contribute to higher systolic blood pressure levels in hypertensive patients

OBJECTIVES

Hypertension (HT) is a complex disorder influenced by both genetic and environmental factors. Recent genome-wide association studies have identified a major risk locus for atherosclerosis on chromosome 9p21.3. SNPs within the coding sequences of CDKN2A/B and the long non-coding RNA CDKN2B-AS1 could potentially contribute to HT development. Thus, this study aimed to investigate whether the frequency of four SNPs on chromosome 9p21.3 affects blood pressure (BP) levels in Turkish HT patients, and to examine correlations between these SNPs, specific SNP haplotypes, and HT.

DESIGN AND METHODS

This is a case-control study comparing HT patients and healthy controls. Real-time polymerase chain reaction (RT-PCR) analysis was utilized to detect SNPs rs10757274, rs2383207, rs10757278, and rs1333049 in 170 HT patients and 180 healthy controls.

RESULTS

Each SNP was detected at significantly higher frequencies in HT patients than in controls (p values 0.001); however, there was no significant link between rs10757274, rs2383207, rs10757278, and rs1333049 SNPs and HT grades. Furthermore, there was a significant association between elevated systolic BP levels and rs1333049 GG genotype (p=0.047), while weight gain and increased fasting glucose levels were significantly associated with rs2383207 AA genotype (p=0.020 and p=0.009, respectively). Lastly, we detected a correlation between GG, GA, and AG haplotypes in block 1 (rs10757274, rs2383207) and GC and AG haplotypes in block 2 (rs10757278, rs1333049) and HT.

CONCLUSIONS

Our findings suggest that SNPs rs10757274, rs2383207, rs10757278, and rs1333049, particularly those within the CDKN2B-AS1 gene, and related haplotypes may confer increased susceptibility to HT development.

Variants on Chromosome 9p21 Confer Risks of Noncardioembolic Cerebral Infarction and Carotid Plaque in the Chinese Han Population

AIMS

Considering that cerebral infarction (CI) may share a common etiological basis with coronary artery disease (CAD), we evaluated six CAD-related single-nucleotide polymorphisms (SNPs) on 9p21 for investigating the effect of 9p21 on CI or carotid plaque in the Chinese Han population.

METHODS

Altogether, 528 patients with noncardioembolic CI (375 with carotid plaque and 153 without carotid plaque) and 258 control subjects were genotyped. Six SNPs previously shown to be associated with CAD were sequenced and assessed for association with CI and carotid plaque using odds ratio (OR) and 95% confidence interval (CI) from logistic regression models.

RESULTS

The G allele frequencies of rs2383206 (OR=1.472, p=0.021) and rs4977574 (OR=1.519, p=0.013) significantly increased in patients with CI without carotid plaque compared with middle-aged patients in the control group. The CI risk was higher among the GG genotype carriers than among GA ＋ AA genotype carriers (OR=1.794, 95% CI=1.059-3.039, p=0.030 for rs2383206; OR=1.866, 95% CI=1.088-3.201, p=0.023 for rs4977574). In comparison with the non-GG genotype, the GG genotype of rs2383206 and rs4977574 combined had a 1.733-fold greater risk of CI in the middle-aged group. SNPs rs2383206 and rs4977574 were also associated with a risk of carotid plaque among patients with CI aged ＞ 65 years (OR=2.329, p=0.018 and OR=1.997, p=0.049, respectively). Moreover, six SNPs were strongly correlated with linkage disequilibrium.

CONCLUSIONS

Genetic variations of rs2383206 and rs4977574 on 9p21 are potentially associated with CI and carotid plaque in the Chinese Han population. Our results provide further evidence that the 9p21 region represents a major risk locus for cerebrovascular diseases.

Association of the rs10757274 SNP with coronary artery disease in a small group of a Pakistani population

Objective:

The present study aimed to investigate the association between the rs10757274 SNP (present on locus 9p21 in the gene for CDKN2B-AS1) and coronary artery disease (CAD) in a local population of Pakistan.

Methods:

It was a case-control study. An allele-specific PCR-based strategy was used for the identification of genotypes. A total of 350 samples were used for the investigation, out of which 220 samples were CAD patients and 130 samples were normal healthy individuals. Effects of parameters, like family history of CAD, smoking, presence of diabetes, and hypertension, in changing the chances of CAD were studied. Odds ratio was estimated with 95% confidence interval.

Results:

A strong association was observed between CAD and factors, like smoking (OR: 1.666; 95% CI: 1.042-2.664), presence of hypertension (OR: 26.55; 95% CI: 15.95-44.20), diabetes (OR: 3.009; 95% CI: 1.841-4.920), and family history of CAD (OR: 4.9; 95% CI: 2.965-8.099). Results for the association between the genotype on the basis of rs10757274 showed a strong association between the GG genotype and the occurrence of CAD (OR: 9.603; 95% CI: 5.746-16.05).

Conclusion:

The present results suggest the importance of the 9p21 locus in modulating the chances of CAD.

Interaction of type 2 diabetes mellitus with chromosome 9p21 rs10757274 polymorphism on the risk of myocardial infarction: a case-control study in Chinese population

Background

Myocardial infarction (MI) is a serious complication of Coronary Artery Disease (CAD). Previous studies have identified genetic variants on chromosome 9p21 and 6p24 that are associated with CAD, but further studies need to be conducted to investigate whether these genetic variants are associated with the pathogenesis of MI. We therefore performed this study to assess the association between the risk of MI and SNP rs10757274 on chromosome 9p21 and SNP rs6903956 on chromosome 6p24, and to explore the gene-environment interactions in a Chinese population.

Methods

A hospital-based case–control study, consisting of 502 MI patients and 308 controls, was conducted in a Chinese population. Demographic, behavioral information and clinical characteristics were collected, and genotyping of the two SNPs was performed using single base primer extension genotyping technology. The unconditional logistic regression (ULR) method was adopted to assess the association of the two SNPs with MI risk. Both generalized multifactor dimensionality reduction (GMDR) and ULR methods were applied to explore the effect of gene-environment interactions on the risk of MI.

Results

After adjusting for covariates, it was observed that SNP rs10757274 on chromosome 9p21 was significantly associated with MI. Compared with subjects carrying the AA genotype, subjects carrying the GA or GG genotypes had a higher MI risk (OR_a = 1.52, 95% CI:1.06–2.19, p_a = 0.0227; OR_a = 2.40, 95% CI:1.51–3.81, p_a = 0.0002, respectively). Furthermore, a two-factor gene-environment interaction model of CDKN2A/B (rs10757274) and type 2 diabetes mellitus (T2DM) was identified to be the best model by GMDR (p = 0.0107), with a maximum prediction accuracy of 59.18%, and a maximum Cross-validation Consistency of 10/10. By using the ULR method, additive interaction analysis found that the combined effect resulted in T2DM-positive subjects with genotype GG/GA having an MI risk 4.38 times that of T2DM-negative subjects with genotype AA (OR_add = 4.38, 95% CI:2.56–7.47, p_add < 0.0001).

Conclusions

These results show that gene polymorphism of CDKN2A/B (rs10757274) is associated with MI risk in a Chinese population. Furthermore, T2DM is likely to have an interaction with CDKN2A/B (rs10757274) that contributes to the risk of MI.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2261-14-170) contains supplementary material, which is available to authorized users.

Association of CDKN2BAS polymorphism rs4977574 with coronary heart disease: a case-control study and a meta-analysis

The goal of our study was to explore the significant association between a non-protein coding single nucleotide polymorphism (SNP) rs4977574 of CDKN2BAS gene and coronary heart disease (CHD). A total of 590 CHD cases and 482 non-CHD controls were involved in the present association study. A strong association of rs4977574 with CHD was observed in females (genotype: p=0.002; allele: p=0.002, odd ratio (OR)=1.57, 95% confidential interval (CI)=1.18-2.08). Moreover, rs4977574 was more likely to be a risk variant of CHD under the recessive model in females (χ2=10.29, p=0.003, OR=2.14, 95% CI=1.31-2.77). A breakdown analysis by age had shown that there was an 87% increased risk of CHD for females younger than 65 years (genotype: χ2=14.64, degrees of freedom (df)=2, p=0.0002; allele: χ2=11.31, df=1, p=0.0008, OR=1.87, 95% CI=1.30-2.70). Similar observation was also found in males younger than 65 years (genotype: χ2=8.63, df=2, p=0.04; allele: χ2=7.55, df=1, p=0.006, OR=1.45, 95% CI=1.11-1.90). p values were adjusted by age, sex, smoking, high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C). Meta-analysis of 23 studies among 36,452 cases and 39,781 controls showed a strong association between rs4977574 and the risk of CHD (p<0.0001, OR=1.27, 95% CI=1.22-1.31).

Validated context-dependent associations of coronary heart disease risk with genotype variation in the chromosome 9p21 region: the Atherosclerosis Risk in Communities study

Markers of the chromosome 9p21 region are regarded as the strongest and most reliably significant genome-wide association study (GWAS) signals for Coronary heart disease (CHD) risk; this was recently confirmed by the CARDIoGRAMplusC4D Consortium meta-analysis. However, while these associations are significant at the population level, they may not be clinically relevant predictors of risk for all individuals. We describe here the results of a study designed to address the question: What is the contribution of context defined by traditional risk factors in determining the utility of DNA sequence variations marking the 9p21 region for explaining variation in CHD risk? We analyzed a sample of 7,589 (3,869 females and 3,720 males) European American participants of the Atherosclerosis Risk in Communities study. We confirmed CHD-SNP genotype associations for two 9p21 region marker SNPs previously identified by the CARDIoGRAMplusC4D Consortium study, of which ARIC was a part. We then tested each marker SNP genotype effect on prediction of CHD within sub-groups of the ARIC sample defined by traditional CHD risk factors by applying a novel multi-model strategy, PRIM. We observed that the effects of SNP genotypes in the 9p21 region were strongest in a sub-group of hypertensives. We subsequently validated the effect of the region in an independent sample from the Copenhagen City Heart Study. Our study suggests that marker SNPs identified as predictors of CHD risk in large population based GWAS may have their greatest utility in explaining risk of disease in particular sub-groups characterized by biological and environmental effects measured by the traditional CHD risk factors.

Association between 9p21 genomic markers and ischemic stroke risk: evidence based on 21 studies

Epidemiological studies indicate a genetic contribution to ischemic stroke risk, but specific genetic variants remain unknown. Recently independent studies reported an association between coronary heart disease and single-nucleotide polymorphisms (SNPs) located at chromosome 9p21 (rs10757278 and proxy SNPs). Given that stroke is a common complication after myocardial infarction, several validation studies have been conducted among various ethnic populations to investigate if the same loci was associated with ischemic stroke (IS), but the results have been inconsistent. To investigate this inconsistency and derive a more precise estimation of the relationship, a meta-analysis of 34,128 cases and 153,428 controls from 21 studies was performed. Potential sources of heterogeneity including ethnicity, sample size, control source and ischemic stroke subtypes were also assessed. Overall, the summary odds ratio of IS was 1.11 (95% CI: 1.07–1.15, P<10⁻⁵) for rs10757278. In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians (3188 cases and 4503 controls; OR = 1.14, 95% CI: 1.07–1.21, P<10⁻⁵) and Caucasians (30505 cases and 145153controls; OR = 1.08, 95% CI: 1.04–1.12, P<10⁻⁵) for the polymorphism; while no significant associations were found among African Americans (435 cases and 3772 controls; OR = 0.97, 95% CI: 0.63–1.51, P = 0.90) in all genetic models. In the subgroup analyses by IS subtypes, significant association was detected only in large vessel stroke group, while no significant associations among small vessel or cardioembolic stroke. When stratified by sample size, and control source, significantly increased risks were found for the polymorphism in all genetic models. This meta-analysis provides accurate and comprehensive estimates of the association of genetic variant at chromosome 9p21 and IS, but these associations vary in different ethnic populations.

Assessment of the 9p21.3 locus in severity of coronary artery disease in the presence and absence of type 2 diabetes

BACKGROUND

The 9p21.3 locus is strongly associated with the risk of coronary artery disease (CAD) and with type 2 diabetes (T2D). We investigated the association of 9p21.3 variants with severity of CAD (defined by the number of vessel diseased [VD]) in the presence and absence of T2D.

METHODS

We tested 11 9p21.3-variants for association in a white Italian study (N = 2,908), and carried out replication in 2 independent white populations, a German study (N = 2,028) and a Canadian Study (N=950). SNP association and permutation analyses were conducted.

RESULTS

We identified two 9p21.3-variants, rs4977574 (P < 4×10(-4)) and rs2383207 (P < 1.5×10(-3)) that were associated with severity of CAD in subjects without T2D. Association of rs4977574 with severity of CAD was confirmed in the Canadian Study. Results from subgroup analysis among patients with T2D showed an interaction between rs10738610 and T2D with P = 4.82×10(-2). Further investigation showed that rs10738610 (P < 1.99×10(-2)) was found to be significantly associated with severity of CAD in subjects with T2D.

CONCLUSIONS

The 9p21.3 locus is significantly associated with severity of CAD. The number of associations of 9p21.3 variants with severity of CAD is variable to the presence and absence of T2D. In a CAD-susceptible region of 115 kb, there is only one variant associated with the severity of coronary vessel disease in the presence of type 2 diabetes.

Effect of 9p21 genetic variation on coronary heart disease is not modified by other risk markers. The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To determine whether the 9p21 SNP association with coronary heart disease is modified by other classical or novel risk markers.

METHODS

The 9p21 SNP (rs10757274) and multiple risk markers were measured in the Atherosclerosis Risk in Communities Study, and incident coronary disease events were ascertained. Effect modification (interaction) of the 9p21 SNP with risk markers was tested in Cox proportional hazard regression models.

RESULTS

The incidence rates of coronary heart disease per 1000 person-years were 14.4, 17.0, and 18.7 for AA, AG, and GG genotypes, yielding hazard ratios of 1.0, 1.20 (95% CI = 1.07-1.36), and 1.34 (95% CI = 1.16-1.53). There was no meaningful evidence of an interaction (all p-interaction > 0.04) between 9p21 SNP and any of 14 other risk markers for coronary heart disease. These included novel markers not previously explored for 9p21 interaction (e.g., cardiac troponin T and N-terminal pro-brain natriuretic peptide).

CONCLUSION

Our study extends evidence that the 9p21 SNP association with coronary heart disease is not modified by classical or novel risk markers. Our findings therefore rule out additional plausible pathways by which 9p21 might have increased coronary heart disease risk.

Genome-wide association study validation identifies novel loci for atherosclerotic cardiovascular disease

BACKGROUND

Genetic variants influencing lipid levels and risk of coronary artery disease (CAD) have been identified by recent genome-wide association studies (GWAS).

OBJECTIVES

To test the association of single nucleotide polymorphisms (SNPs) implicated in lipoprotein metabolism and CAD in GWAS with atherosclerotic cardiovascular disease (ASCVD, including ischemic stroke [IS] and myocardial infarction [MI] phenotypes).

PATIENTS AND METHODS

A two-stage genetic association study was conducted in the Chinese Hans population. Stage I included a cohort with 451 IS cases and 462 controls for association analysis using 92 SNPs. Stage II examined the associations of eight positive variants and five additional variants with IS, MI and ASCVD in a cohort with 779 IS cases and 836 controls and a cohort with 824 MI cases and 737 controls.

RESULTS

The T allele of rs4731702 located near the KLF14 gene was associated with a decreased risk of MI with an odds ratio (OR) of 0.72 (P<3.85×10(-3)). The rs4731702-T allele was also associated with a decreased risk of ASCVD with an OR of 0.78 (Pmeta-analysis<5.43×10(-4)). In addition, we found that a missense variant of KLF14, rs111400400 (Ser58Pro), was associated with MI.

CONCLUSION

Genetic variants newly identified near/in the KLF14 gene were implicated in the aetiology of atherosclerotic-related phenotypes.

Variants on chromosome 9p21.3 correlated with ANRIL expression contribute to stroke risk and recurrence in a large prospective stroke population

BACKGROUND AND PURPOSE

ANRIL encodes a long antisense noncoding RNA in the INK4 locus. Although ANRIL has been proven to be associated with coronary heart disease, its roles in stroke are inconsistent, and sparse data are available regarding hemorrhagic stroke.

METHODS

A Chinese case-control study was conducted, comprising 1657 cases (724 atherothrombosis, 466 lacunar infarction, and 462 hemorrhagic strokes) and 1664 controls. Stroke patients were prospectively followed-up for a median of 4.5 (range, 0.1-6.0) years. Expression of ANRIL transcripts was examined in 42 human atherosclerotic plaques.

RESULTS

After adjustment for vascular risk factors and correction for multiple comparisons, subjects carrying the GG genotype of rs10757278 had 1.47-fold (95% CI, 1.11-1.89; P=0.05) and 1.60-fold (95% CI, 1.16-2.15; P=0.04) increased risk for atherothrombotic and hemorrhagic strokes, respectively. During the follow-up, 317 recurrent strokes and 301 deaths from all causes were documented. Subjects carrying rs10757278GG had higher risk for stroke recurrence (relative risk [RR],1.56; 95% CI,1.15-2.12; P=0.005) and cardiovascular mortality (RR, 2.0; 95% CI, 1.26-3.18; P=0.003), respectively. Rs10757274 was also associated with stroke risk and recurrence. Family history of stroke further increased the stroke risk by 2.37-fold (95% CI, 1.38-4.06; P=0.01) and recurrent stroke risk by 2.45-fold (95% CI, 1.56-3.86; P<0.0001) respectively, when compared with those carrying none of G-alleles and without family history. Finally, rs10757278 was associated with differential expression of the ANRIL transcripts.

CONCLUSIONS

Our findings indicated that the ANRIL may serve as a novel genetic marker for the risk of atherothrombotic and hemorrhagic stroke and their recurrence.

p14ARF genetic polymorphisms and susceptibility to second primary malignancy in patients with index squamous cell carcinoma of the head and neck

BACKGROUND

p14(ARF) , an alternate reading frame (ARF) product of the cyclin-dependent kinase inhibitor 2A locus, plays a critical role in crosstalk between the tumor protein 53 (p53) and retinoblastoma (Rb) pathways and in cellular anticancer mechanisms. Therefore, the authors of this report investigated the association between single nucleotide polymorphisms (SNPs) of the p14(ARF) gene and the risk of developing a second primary malignancy (SPM) after an index squamous cell carcinoma of the head and neck (SCCHN).

METHODS

The log-rank test and Cox proportional hazards models were used to assess the association of 2 p14(ARF) SNPs (reference SNP [rs]3731217 and rs3088440) with SPM-free survival and with the risk of developing an SPM among 1287 patients who had SCCHN.

RESULTS

Patients with either p14(ARF) variant genotypes of the 2 polymorphisms had a significantly reduced SPM-free survival compared with patients with no variant genotypes (log-rank test; P = .006). Compared with the p14(ARF) thymine-thymine (TT) and guanine-guanine (GG) genotypes, the variant genotypes of p14(ARF) TG/GG and guanine-adenine (GA)/AA were associated with a significantly moderately increased risk of developing an SPM (p14(ARF) rs3731217: adjusted hazard ratio [aHR], 1.48; 95% confidence interval [CI], 1.00-2.19; p14(ARF) rs3088440: aHR, 1.61; 95% CI, 1.07-2.43). Moreover, after combining the variant genotypes of the 2 SNPs, patients who had variant genotypes were at significantly greater risk of developing an SPM compared with patients who had no variant genotypes (aHR, 3.07; 95% CI, 1.54-6.12), and the risk was particularly pronounced in several subgroups.

CONCLUSIONS

The current results suggested that there is a modestly increased risk of developing an SPM after an index SCCHN with each p14(ARF) polymorphism, and there is an even greater risk of developing an SPM for patients with combined variant genotypes of the 2 SNPs. Therefore, p14(ARF) polymorphisms may be susceptible markers of the risk of developing an SPM in patients with SCCHN.

Bivariate genetic association of KIAA1797 with heart rate in American Indians: the Strong Heart Family Study

Heart rate (HR) has been identified as a risk factor for cardiovascular disease (CVD), yet little is known regarding genetic factors influencing this phenotype. Previous research in American Indians (AIs) from the Strong Heart Family Study (SHFS) identified a significant quantitative trait locus (QTL) for HR on chromosome 9p21. Genetic association on HR was conducted in the SHFS. HR was measured from electrocardiogram (ECG) and echocardiograph (Echo) Doppler recordings. We examined 2248 single-nucleotide polymorphisms (SNPs) on chromosome 9p21 for association using a gene-centric statistical test. We replicated the aforementioned QTL [logarithm of odds (LOD) = 4.83; genome-wide P= 0.0003] on chromosome 9p21 in one SHFS population using joint linkage of ECG and Echo HR. After correcting for effective number of SNPs using a gene-centric test, six SNPs (rs7875153, rs7848524, rs4446809, rs10964759, rs1125488 and rs7853123) remained significant. We applied a novel bivariate association method, which was a joint test of association of a single locus to two traits using a standard additive genetic model. The SNP, rs7875153, provided the strongest evidence for association (P = 7.14 x 10(-6)). This SNP (rs7875153) is rare (minor allele frequency = 0.02) in AIs and is located within intron 9 of the gene KIAA1797. To support this association, we applied lymphocyte RNA expression data from the San Antonio Family Heart Study, a longitudinal study of CVD in Mexican Americans. Expression levels of KIAA1797 were significantly associated (P = 0.012) with HR. These findings in independent populations support that KIAA1797 genetic variation may be associated with HR but elucidation of a functional relationship requires additional study.

Chromosome 9p21 in ischemic stroke: population structure and meta-analysis

BACKGROUND AND PURPOSE

Sequence variants on chromosome 9p21.3 are implicated in coronary artery disease and myocardial infarction, but studies in ischemic stroke have produced inconsistent results. We investigated whether these conflicting findings were due to false-positive studies confounded by population stratification or false-negative studies that failed to account for effects specific to certain stroke subtypes.

METHODS

After assessing for population stratification at 9p21.3 using genomewide data, we meta-analyzed 8 ischemic stroke studies. This analysis focused on 2 single nucleotide polymorphisms, rs1537378 and rs10757278, because these variants are in strong linkage disequilibrium with most single nucleotide polymorphisms analyzed in prior studies of the region.

RESULTS

Principal component analysis of the genomewide data showed no evidence of population stratification at that locus. Meta-analysis confirmed that both rs1537378 and rs10757278 are risk factors for ischemic stroke (ORs, 1.09 [P=0.0014] and 1.11 [P=0.001], respectively). Subtype analysis revealed a substantial increase in the effect of each single nucleotide polymorphism for risk of large artery stroke, achieving an effect size similar to that seen in coronary artery disease/myocardial infarction.

CONCLUSIONS

Variants on 9p21.3 are associated with ischemic stroke, and restriction of analysis to large artery stroke increases effect size toward that observed in prior association studies of coronary artery disease/myocardial infarction. Previous inconsistent findings are best explained by this subtype specificity rather than any unmeasured confounding by population stratification.