The contribution of a 9p21.3 variant, a KIF6 variant, and C-reactive protein to predicting risk of myocardial infarction in a prospective study

Impact of 719Trp>Arg Polymorphism of KIF 6 Gene on Contrast Induced Nephropathy in Patients Undergoing Coronary Angiography or Percutaneous Coronary Intervention

Background:

The identification of preventive strategies, such as statin therapy, is crucial for the management of contrast-induced nephropathy (CIN). Several studies showed the association between KIF6 polymorphism (replacement of Trp719 with Arg) and an increased cardiovascular risk, while others showed a correlation between ‘pleiotropic’ effects of statins and a reduction in cardiovascular events in the population with the risk allele due to the documented modulation of response to statin by KIF6 polymorphism. Aim of this study is to assess the impact of KIF6 polymorphism on the development of CIN.

Methods:

We analysed 1253 consecutive patients undergoing coronary angiography/PCI. Serum creatinine was collected at baseline, 24 and 48 hours after contrast exposure. We identified the different allelic patterns and assessed the incidence of CIN (absolute increase of 0.5mg/dL or relative >25% in creatinine at 24 and 48h).

Results:

KIF6 Arg mutation was found in 669 patients (heterozygotes n = 525, homozygotes n = 144). The total prevalence of CIN was 12.5% and we did not find any association between KIF6 polymorphism and CIN development (11.3%, 13.7%, 13.2% p = 0.30). At subgroups analysis among statin ‘naïve’ patients we found a higher prevalence of CIN in homozygous patients as compared to wild-type (20.7% vs 11.3%, p = 0.05), while opposite results were observed among patients with statin therapy (8.6% vs 13.2%, p = 0.28).

Conclusion:

KIF6 homozygous Arg was associated with a significant increase in the risk of CIN only among statin naive patients. Future studies are needed to evaluate the beneficial effects of statin especially in this subset of patients.

The Genetics of Ischemic Heart Disease: From Current Knowledge to Clinical Implications

Ischemic heart disease continues to cause high morbidity and mortality. Its prevalence is expected to increase due to population aging, and its prevention is a major goal of health policies. The risk of developing ischemic heart disease is related to a complex interplay between genetic, environmental, and lifestyle factors. In the last decade, considerable progress has been made in knowledge of the genetic architecture of this disease. This narrative review provides an overview of current knowledge of the genetics of ischemic heart disease and of its translation to clinical practice: identification of new therapeutic targets, assessment of the causal relationship between biomarkers and disease, improved risk prediction, and identification of responders and nonresponders to specific drugs (pharmacogenomics).

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.

Genetic variants at chromosome 9p21 and risk of first versus subsequent coronary heart disease events: a systematic review and meta-analysis

Objectives

The purpose of this analysis was to compare the association between variants at the chromosome 9p21 locus (Ch9p21) and risk of first versus subsequent coronary heart disease (CHD) events through systematic review and meta-analysis.

Background

Ch9p21 is a recognized risk factor for a first CHD event. However, its association with risk of subsequent events in patients with established CHD is less clear.

Methods

We searched PubMed and EMBASE for prospective studies reporting association of Ch9p21 with incident CHD events and extracted information on cohort type (individuals without prior CHD or individuals with established CHD) and effect estimates for risk of events.

Results

We identified 31 cohorts reporting on 193,372 individuals. Among the 16 cohorts of individuals without prior CHD (n = 168,209), there were 15,664 first CHD events. Ch9p21 was associated with a pooled hazard ratio (HR) of a first event of 1.19 (95% confidence interval: 1.17 to 1.22) per risk allele. In individuals with established CHD (n = 25,163), there were 4,436 subsequent events providing >99% and 91% power to detect a per-allele HR of 1.19 or 1.10, respectively. The pooled HR for subsequent events was 1.01 (95% confidence interval: 0.97 to 1.06) per risk allele. There was strong evidence of heterogeneity between the effect estimates for first and subsequent events (p value for heterogeneity = 5.6 × 10⁻¹¹). We found no evidence for biases to account for these findings.

Conclusions

Ch9p21 shows differential association with risk of first versus subsequent CHD events. This has implications for genetic risk prediction in patients with established CHD and for mechanistic understanding of how Ch9p21 influences risk of CHD.

Pathogenesis of coronary artery disease: focus on genetic risk factors and identification of genetic variants

Coronary artery disease (CAD) is the leading cause of death and disability worldwide, and its prevalence is expected to increase in the coming years. CAD events are caused by the interplay of genetic and environmental factors, the effects of which are mainly mediated through cardiovascular risk factors. The techniques used to study the genetic basis of these diseases have evolved from linkage studies to candidate gene studies and genome-wide association studies. Linkage studies have been able to identify genetic variants associated with monogenic diseases, whereas genome-wide association studies have been more successful in determining genetic variants associated with complex diseases. Currently, genome-wide association studies have identified approximately 40 loci that explain 6% of the heritability of CAD. The application of this knowledge to clinical practice is challenging, but can be achieved using various strategies, such as genetic variants to identify new therapeutic targets, personal genetic information to improve disease risk prediction, and pharmacogenomics. The main aim of this narrative review is to provide a general overview of our current understanding of the genetics of coronary artery disease and its potential clinical utility.

The combination of 9p21.3 genotype and biomarker profile improves a peripheral artery disease risk prediction model

Peripheral artery disease (PAD) is a highly morbid condition affecting more than 8 million Americans. Frequently, PAD patients are unrecognized and therefore do not receive appropriate therapies. Therefore, new methods to identify PAD have been pursued, but have thus far had only modest success. Here we describe a new approach combining genomic and metabolic information to enhance the diagnosis of PAD. We measured the genotype of the chromosome 9p21 cardiovascular-risk polymorphism rs10757269 as well as the biomarkers C-reactive protein, cystatin C, β2-microglobulin, and plasma glucose in a study population of 393 patients undergoing coronary angiography. The rs10757269 allele was associated with PAD status (ankle-brachial index < 0.9) independent of biomarkers and traditional cardiovascular risk factors (odds ratio = 1.92; 95% confidence interval, 1.29-2.85). Importantly, compared to a previously validated risk factor-based PAD prediction model, the addition of biomarkers and rs10757269 significantly and incrementally improved PAD risk prediction as assessed by the net reclassification index (NRI = 33.5%; p = 0.001) and integrated discrimination improvement (IDI = 0.016; p = 0.017). In conclusion, a model including a panel of biomarkers, which includes both genomic information (which is reflective of heritable risk) and metabolic information (which integrates environmental exposures), predicts the presence or absence of PAD better than established risk models, suggesting clinical utility for the diagnosis of PAD.

Association of KIF6 variant with lipid level and angiographic coronary artery disease events risk in the Han Chinese population

KIF6 is a class of molecular motor from the kinesin superfamily. Recently, multiple large studies consisting mainly of Europeans have shown that KIF6 Trp719Arg SNP may be a new predictive factor for coronary artery disease (CAD) event risk. The allelic frequency distribution of rs20455 is different in various populations, yet studies among the Han population, one of the largest ethnic groups in the World, have not been conducted. This study is aimed to evaluate the association of KIF6 Trp719Arg variant with angiographic CAD and serum lipid levels in the Han population from northern China. In this case-controlled study, peripheral blood samples were collected from 356 patients and 568 controls of Han Chinese origin. Genotyping was performed by a high-resolution melting curve. The impact of rs20455 on CAD and non-fatal MI was evaluated in a dominant genetic model with stepwise multiple regression analysis. There were no significant differences of genotypes and allele frequency between angiographic CAD and control groups (p > 0.05); however, that of MI and non-MI subgroups were significant differences (p < 0.05). After adjusting for significant risk factors, angiographic CAD risk was not significantly increased in 719Arg allele carriers compared with non-carriers. Further analysis revealed that the non-fatal MI risk and triglyceride levels were significantly higher in 719Arg allele carriers than non-carriers. In conclusion, KIF6 719Arg allele was not an independent risk factor for angiographic CAD susceptibility in Han populations from northern China. However, it was associated with a significantly higher TG level, which may indicate an increased myocardial infarction risk in angiographic CAD patients.