Genetic variation in angiotensin-converting enzyme-related pathways associated with sudden cardiac arrest risk

The role of genetic polymorphisms in KCNN2 in cardiovascular complications in patients with renal failure

Patients with end-stage renal disease (ESRD) are at a higher risk of cardiovascular (CV) complications and mortality compared to the general population. This study aimed to investigate the genetic polymorphisms of KCNN2, a key gene encoding a subtype of small-conductance calcium-activated potassium (SK) channels, which regulate an important SK current pathway potentially involved in the development of CV complications, particularly arrhythmias, in ESRD patients. A total of 169 ESRD patients were enrolled in this study. The patients were divided into two groups based on the presence of CV complications: Group I, consisting of 84 patients without CV complications, and Group II, comprising 85 patients with CV complications. Twelve tagging single nucleotide polymorphisms (tSNPs) in KCNN2 were examined. Polymerase chain reaction (PCR) was performed, and genotyping was correlated with CV complications in each group. The TC and CC genotypes of rs10076582, and the GT and TT genotypes of rs11738819 in the KCNN2 gene, were associated with an increased risk of CV complications in ESRD patients. After adjusting for potential risk factors, these associations remained significant. Additionally, KCNN2 haplotypes with the allele combinations GGCCCTCCGAG and AGTCCTCCGGT were significantly associated with a higher risk of CV complications in ESRD patients. In conclusion, our findings report that specific genetic polymorphisms in the KCNN2 gene, particularly the rs10076582 and rs11738819 variants, as well as GGCCCTCCGAG and AGTCCTCCGGT haplotypes, are significantly associated with an increased risk of cardiovascular complications in ESRD patients. These genetic markers may serve as potential biomarkers for identifying individuals at high risk of cardiovascular complications in this vulnerable population.

Arrhythmias after COVID-19 Vaccination: Have We Left All Stones Unturned?

SARS-CoV-2 vaccination offered the opportunity to emerge from the pandemic and, thereby, worldwide health, social, and economic disasters. However, in addition to efficacy, safety is an important issue for any vaccine. The mRNA-based vaccine platform is considered to be safe, but side effects are being reported more frequently as more and more people around the world become treated. Myopericarditis is the major, but not the only cardiovascular complication of this vaccine; hence it is important not to underestimate other side effects. We report a case series of patients affected by cardiac arrhythmias post-mRNA vaccine from our clinical practice and the literature. Reviewing the official vigilance database, we found that heart rhythm disorders after COVID vaccination are not uncommon and deserve more clinical and scientific attention. Since the COVID vaccine is the only vaccination related to this side effect, questions arose about whether these vaccines could affect heart conduction. Although the risk-benefit ratio is clearly in favor of vaccination, heart rhythm disorders are not a negligible issue, and there are red flags in the literature about the risk of post-vaccination malignant arrhythmias in some predisposed patients. In light of these findings, we reviewed the potential molecular pathways for the COVID vaccine to impact cardiac electrophysiology and cause heart rhythm disorders.

Integrated proteomic and metabolomic profile analyses of cardiac valves revealed molecular mechanisms and targets in calcific aortic valve disease

Background

This study aimed to define changes in the metabolic and protein profiles of patients with calcific aortic valve disease (CAVD).

Methods and results

We analyzed cardiac valve samples of patients with and without (control) CAVD (n = 24 per group) using untargeted metabolomics and tandem mass tag-based quantitative proteomics. Significantly different metabolites and proteins between the CAVD and control groups were screened; then, functional enrichment was analyzed. We analyzed co-expressed differential metabolites and proteins, and constructed a metabolite-protein-pathway network. The expression of key proteins was validated using western blotting. Differential analysis identified 229 metabolites in CAVD among which, 2-aminophenol, hydroxykynurenine, erythritol, carnosine, and choline were the top five. Proteomic analysis identified 549 differentially expressed proteins in CAVD, most of which were localized in the nuclear, cytoplasmic, extracellular, and plasma membranes. Levels of selenium binding protein 1 (SELENBP1) positively correlated with multiple metabolites. Adenosine triphosphate-binding cassette transporters, starch and sucrose metabolism, hypoxia-inducible factor 1 (HIF-1) signaling, and purine metabolism were key pathways in the network. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), calcium²⁺/calmodulin-dependent protein kinase II delta (CAMK2D), and ATP binding cassette subfamily a member 8 (ABCA8) were identified as hub proteins in the metabolite-protein-pathway network as they interacted with ADP, glucose 6-phosphate, choline, and other proteins. Western blotting confirmed that ENPP1 was upregulated, whereas ABCA8 and CAMK2D were downregulated in CAVD samples.

Conclusion

The metabolic and protein profiles of cardiac valves from patients with CAVD significantly changed. The present findings provide a holistic view of the molecular mechanisms underlying CAVD that may lead to the development of novel diagnostic biomarkers and therapeutic targets to treat CAVD.

Association of miR-155 and Angiotensin Receptor Type 1 Polymorphisms with the Risk of Ischemic Stroke in a Chinese Population

There is increasing evidence suggesting that dysregulation of miR-155 and its target angiotensin receptor type 1 (AT1R) are linked to the incidence of ischemic stroke (IS), but the underlying mechanisms remain to be clarified. In this study, we therefore sought to investigate how miR-155 and AT1R polymorphisms affect IS risk. We included 579 IS patients and 509 age-matched controls in the present analysis, genotyping individuals for the rs767649 polymorphism in miR-155, as well as for the rs1492099 and rs275653 polymorphisms in AT1R via iMLDR-TM genotyping technology. The allele and genotype frequencies for the assessed polymorphisms were comparable in IS patients and controls, without any detectable association between AT1R haplotype and IS risk. We conducted additional trial of ORG 10172 in acute stroke treatment-mediated stratification, which indicated that the AT1R rs1492099 T allele was linked to a decreased risk of large-artery atherosclerosis (LAA) stroke. We further found that those with the AT1R rs275653 AA genotype had a decreased risk of small-artery occlusion (SAO) strokes. We further confirmed elevated miR-155 expression in IS patients, but observed no link between the rs767649 polymorphism and expression of this microRNA. Similarly, rs1492099 and rs275653 polymorphisms did not impact AT1R expression levels. The miR-155 rs767649 polymorphism does not seem to be a key determinant of IS risk, whereas the AT1R rs1492099 polymorphism is linked to reduced LAA-stroke risk, and the rs275653 AA genotype is potentially protective against SAO strokes.

Usefulness of Single Nucleotide Polymorphisms as Predictors of Sudden Cardiac Death

The pathophysiology of sudden cardiac death (SCD) remains incompletely understood. Genetic mutations can create a favorable substrate for SCD. Our aim is to evaluate the evidence of single nucleotide polymorphisms (SNPs) as predictors of SCD. We searched the Medline database (2000 to 2017) and selected all case-control or cohort studies that reported associations between SNPs and SCD. Our search terms included "polymorphisms" and "sudden death." We collected the study design, population ethnic background, gene testing strategy, the association between the SNP and SCD, and the cardiovascular comorbidities of the population. Our search yielded 723 studies, of which we included 24 based upon our inclusion criteria. The studies had a total population of 78,165 participants, with a median age of 62.5 years (IQR 56 to 66) and 35% (IQR 13 to 32) were female. Almost all studies were conducted in white patients of European descent and the most commonly used genetic strategy was candidate gene panels. Fifteen of the studies had a case-control design that included SCD patients without known heart disease as the comparison group and the other 9 studies included patients with heart failure and coronary artery disease. The studies evaluated 53 SNPs and the most common genetic loci were SCN5A, RyR2, CASQ2, NOSA1P, and AGTR. SNPs with the 3 strongest statistically significant ORs >1 were: rs6684209 of CASQ2 (odds ratio [OR] 19), rs3814843 of CALM1 (OR 5.5), and rs35594137 of GJA5 (OR 3.6). In Conclusion, many SNPs are associated with SCD, with the strongest associations seen in SNPs of genes related to intracellular calcium handling. These findings were generated primarily using a candidate gene strategy in white patients with European descent.

Association of ACE2 genetic polymorphisms with hypertension-related target organ damages in south Xinjiang

Essential hypertension (EH) is a principal contributing factor in worldwide cardiovascular disease mortality. Although interventions that minimize environmental risk factors for EH are associated with reduced cardiovascular disease, such approaches are limited for individuals with high genetic EH risk. In this study, we investigated possible associations between ACE2 polymorphisms and hypertension-related target organ damages in south Xinjiang, China. Four hundred and two hypertensive patients were enrolled as study participants in an EH group, and 233 normotensive individuals were enrolled as control subjects. Participants were recruited from the south Xinjiang region. Fourteen ACE2 polymorphisms were genotyped by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Risk genotypes of rs2074192 (TT+CT, OR = 1.72, 95% CI: 1.17–2.53), rs2106809 (TT, OR = 1.71, 95% CI: 1.13–2.58), rs4240157 (CC+CT, OR = 1.99, 95% CI: 1.17–3.41), rs4646155 (TT+CT, OR = 1.94, 95% CI: 1.06–3.54), rs4646188 (TT+CT, OR = 3.25, 95% CI: 1.95–5.41), rs4830542 (CC+CT, OR = 1.88, 95% CI: 1.10–3.23), and rs879922 (CC+CG, OR = 4.86, 95% CI: 2.74–8.64) were associated with EH. Hypertensive patients carrying the control genotype of rs2074192 (CC, OR = 2.37, 95% CI: 1.28–4.39) were associated with CAS ≥50%, while those carrying a high-EH-risk genotype of rs4240157 (OR = 2.62, 95% CI: 1.24–5.54), rs4646155 (OR = 2.44, 95% CI: 1.16–5.10), or rs4830542 (CC+CT, OR = 2.20, 95% CI: 1.03–4.69) were associated with atrial fibrillation (AF), larger left atrial diameter, and higher levels of renin–angiotensin–aldosterone system (RAAS) activation (renin and angiotensin I/II). In conclusion, the ACE2 variant rs2074192 was associated with EH and EH with CAS ≥50%, while 3 ACE2 variants (rs4240157, rs4646155, and rs4830542) were associated with EH- and hypertension-related AF and left atrial remodeling in south Xinjiang, China.

Association of ACE2 polymorphisms with susceptibility to essential hypertension and dyslipidemia in Xinjiang, China

Background

Cardiovascular benefits by reversing environmental risks factors for essential hypertension (EH) and dyslipidemia could be weaken by high genetic risk. We investigated possible associations between ACE2 polymorphisms and dyslipidemia in patients with EH.

Methods

Four hundred and two hypertensive patients were enrolled in an EH group and 233 normotensive individuals were enrolled as control group from the Xinjiang region of China. Fourteen ACE2 polymorphisms were genotyped by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Results

Participants carrying T allele (TT + CT) of rs2074192 (P = 0.006), rs4646155 (P = 0.030) and rs4646188 (P < 0.001), C allele (CT + CT or CC + CG) of rs4240157 (P = 0.012), rs4830542 (P = 0.020) and rs879922 (P < 0.001) and TT genotype of rs2106809 (P = 0.012) were associated with EH. Meanwhile,ACE2 SNPs also exhibited association with dyslipidemia but exhibited obvious heterogeneity. rs1978124 (TT + CT, P = 0.009), rs2106809 (TT, P = 0.045), rs233575 (CC + CT, P = 0.018), rs4646188 (CC, P = 0.011) and rs879922 (CC + CG, P = 0.003) were association with increased LDL-C (≥1.8 mmol/L). rs2106809 (CC + CT, P < 0.001), rs2285666(TT + CT, P = 0.017), rs4646142(CC + CG, P = 0.044), rs4646155(TT + CT, P < 0.001) and rs4646188(TT + CT, P = 0.033) were association with decreased HDL-C (< 1.0 mmol/L). rs2074192 (TT + CT, P = 0.012), rs4240157 (CC + CT, P = 0.027), rs4646156 (AA+AT, P = 0.007), rs4646188 (TT + CT, P = 0.005), rs4830542 (CC + CT, P = 0.047) and rs879922 (CC + CG, P = 0.001) were association with increased TC (≥5.2 mmol/L). rs2106809 (P = 0.034) and rs4646188 (P = 0.013) were associated with hypertriglyceridemia. Further, ischemic stroke was more prevalent with rs4240157 (CC + CT, P = 0.043), rs4646188 (CC + CT, P = 0.013) and rs4830542 (CC + CT, P = 0.037). In addition, rs2048683 and rs6632677 were not association with EH, dyslipidemia and ischemic stroke.

Conclusion

The ACE2 rs4646188 variant may be a potential and optimal genetic susceptibility marker for EH, dyslipidemia and its related ischemic stroke.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0890-6) contains supplementary material, which is available to authorized users.

ACE2 polymorphisms associated with cardiovascular risk in Uygurs with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2D), rapidly increasing to epidemic proportions, globally escalates cardiovascular disease risk. Although intensive interventions and comprehensive management of environmental risks factors for T2D are associated with reduced cardiovascular disease, such approaches are limited for individuals with high genetic T2D risk. In this study we investigated possible associations of ACE2 polymorphisms and cardiovascular risks in Uygur patients with T2D.

Methods

275 Uygur T2D patients and 272 non-diabetic Uygur individuals were enrolled as study participants. 14 ACE2 polymorphisms were genotyped by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Results

ACE2 SNP rs1978124, rs2048683, rs2074192, rs233575, rs4240157, rs4646156, rs4646188 and rs879922 were associated with T2D (all P < 0.05). The 8 diabetic risk related ACE2 SNPs were further associated with diabetic related cardiovascular complications or events but exhibited heterogeneity as fellows: firstly, almost all diabetic risk related ACE2 SNPs (all P < 0.05) were associated with increased SBP except rs1978124 and rs2074192, while rs2074192, rs4646188 and rs879922 were associated elevated DBP (all P < 0.05). Secondly, SNP rs4646188 was not correlated with any type of dyslipidemia (TRIG, HDL-C, LDL-C or CHOL), and the other 7 diabetic risk related loci were at least correlated with one type of dyslipidemia (all P < 0.05). In particular, rs879922 were simultaneously correlated with four type of dyslipidemia (all P < 0.05). Thirdly, ACE2 SNP rs2074192 and rs879922 were associated with carotid arteriosclerosis stenosis (CAS) ≥ 50% (both P < 0.05). Fourthly, ACE2 SNP rs2074192, rs4240157, rs4646188 and 879922 were associated with increased MAU (all P < 0.05). In addition, ACE2 SNP rs2048683, rs4240157, rs4646156, rs4646188 and rs879922 were linked to heavier LVMI (all P < 0.05), but only rs4240157, rs4646156 and rs4646188 were associated with lower LVEF (all P < 0.05).

Conclusion

ACE2 SNP rs879922 may be a common genetic loci and optimal genetic susceptibility marker for T2D and T2D related cardiovascular risks in Uygurs.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0771-3) contains supplementary material, which is available to authorized users.

Genetic variations involved in sudden cardiac death and their associations and interactions

Although the mechanism of sudden cardiac death (SCD) in heart failure is not completely known, genetic variations are known to play key roles in this process. Increasing numbers of mutations and variants are being discovered through genome-wide association studies. The genetic variations involved in the mechanisms of SCD have aroused widespread concern. Comprehensive understanding of the genetic variations involved in SCD may help prevent it. To this end, we briefly reviewed the genetic variations involved in SCD and their associations and interactions, and observed that cardiac ion channels are the core molecules involved in this process. Genetic variations involved in cardiac structure, cardiogenesis and development, cell division and differentiation, and DNA replication and transcription are all speculated to be loci involved in SCD. Additionally, the systems involved in neurohumoral regulation as well as substance and energy metabolism are also potentially responsible for susceptibility to SCD. They form an elaborate network and mutually interact with each other to govern the fate of SCD-susceptible individuals.

In the Wrong Place with the Wrong SNP: The Association Between Stressful Neighborhoods and Cardiac Arrest Within Beta-2-adrenergic Receptor Variants

BACKGROUND

Sudden cardiac arrest has been linked independently both to stressful neighborhood conditions and to polymorphisms in the ADRB2 gene. The ADRB2 gene mediates sympathetic activation in response to stress. Therefore, if neighborhood conditions cause cardiac arrest through the stress pathway, the ADRB2 variant may modify the association between neighborhood conditions, such as socioeconomic deprivation and incidence of cardiac arrest.

METHODS

The Cardiac Arrest Blood Study Repository is a population-based repository of specimens and other data from adult cardiac arrest patients residing in King County, Washington. Cases (n = 1,539) were 25- to 100-year-old individuals of European descent who experienced out-of-hospital cardiac arrest from 1988 to 2004. Interactions between neighborhood conditions and the ADRB2 genotype on cardiac arrest risk were assessed in a case-only study design. Gene-environment independence was assessed in blood samples obtained from King County residents initially contacted by random-digit dialing.

RESULTS

Fewer than 4% of study subjects resided in socioeconomically deprived neighborhoods. Nonetheless, the case-only analysis indicated the presence of supramultiplicative interaction of socioeconomic deprivation and the homozygous Gln27Glu variant (case-only odds ratio: 1.8 [95% confidence interval: 1.0, 2.9]). Interactions between population density and the homozygous Gln27Glu variant were weaker (case-only odds ratio: 1.2 [95% confidence interval: 0.97, 1.5]).

CONCLUSIONS

Findings support a supramultiplicative interaction between the Gln27Glu ADRB2 variant and socioeconomic deprivation among individuals of European descent. This result is consistent with the hypothesis that the elevation in cardiac arrest risk associated with socioeconomic deprivation operates through the stress pathway.

KCNN2 polymorphisms and cardiac tachyarrhythmias

Potassium calcium-activated channel subfamily N member 2 (KCNN2) encodes an integral membrane protein that forms small-conductance calcium-activated potassium (SK) channels. Recent studies in animal models show that SK channels are important in atrial and ventricular repolarization and arrhythmogenesis. However, the importance of SK channels in human arrhythmia remains unclear. The purpose of the present study was to test the association between genetic polymorphism of the SK2 channel and the occurrence of cardiac tachyarrhythmias in humans. We enrolled 327 Han Chinese, including 72 with clinically significant ventricular tachyarrhythmias (VTa) who had a history of aborted sudden cardiac death (SCD) or unexplained syncope, 98 with a history of atrial fibrillation (AF), and 144 normal controls. We genotyped 12 representative tag single nucleotide polymorphisms (SNPs) across a 141-kb genetic region containing the KCNN2 gene; these captured the full haplotype information. The rs13184658 and rs10076582 variants of KCNN2 were associated with VTa in both the additive and dominant models (odds ratio [OR] 2.89, 95% confidence interval [CI] = 1.505-5.545, P = 0.001; and OR 2.55, 95% CI = 1.428-4.566, P = 0.002, respectively). After adjustment for potential risk factors, the association remained significant. The population attributable risks of these 2 variants of VTa were 17.3% and 10.6%, respectively. One variant (rs13184658) showed weak but significant association with AF in a dominant model (OR 1.91, CI = 1.025-3.570], P = 0.042). There was a significant association between the KCNN2 variants and clinically significant VTa. These findings suggest an association between KCNN2 and VTa; it also appears that KCNN2 variants may be adjunctive markers for risk stratification in patients susceptible to SCD.

Association of Genetic Polymorphisms of Renin-Angiotensin-Aldosterone System-Related Genes with Arterio-Venous Fistula Malfunction in Hemodialysis Patients

Hemodialysis (HD) is the most commonly-used renal replacement therapy for patients with end-stage renal disease worldwide. Arterio-venous fistula (AVF) is the vascular access of choice for HD patients with lowest risk of infection and thrombosis. In addition to environmental factors, genetic factors may also contribute to malfunction of AVF. Previous studies have demonstrated the effect of genotype polymorphisms of angiotensin converting enzyme on vascular access malfunction. We conducted a multicenter, cross-sectional study to evaluate the association between genetic polymorphisms of renin-angiotensin-aldosterone system and AVF malfunction. Totally, 577 patients were enrolled. Their mean age was 60 years old and 53% were male. HD patients with AVF malfunction had longer duration of HD (92.5 ± 68.1 vs. 61.2 ± 51.9 months, p < 0.001), lower prevalence of hypertension (44.8% vs. 55.3%, p = 0.025), right-sided (31.8% vs. 18.4%, p = 0.002) and upper arm AVF (26.6% vs. 9.7%, p < 0.001), and higher mean dynamic venous pressure (DVP) (147.8 ± 28.3 vs. 139.8 ± 30.0, p = 0.021). In subgroup analysis of different genders, location of AVF and DVP remained significant clinical risk factors of AVF malfunction in univariate and multivariate binary logistic regression in female HD patients. Among male HD patients, univariate binary logistic regression analysis revealed that right-side AVF and upper arm location are two important clinical risk factors. In addition, two single nucleotide polymorphisms (SNPs), rs275653 (Odds ratio 1.90, p = 0.038) and rs1492099 (Odds ratio 2.29, p = 0.017) of angiotensin II receptor 1 (AGTR1), were associated with increased risk of AVF malfunction. After adjustment for age and other clinical factors, minor allele-containing genotype polymorphisms (AA and CA) of rs1492099 still remained to be a significant risk factor of AVF malfunction (Odds ratio 3.63, p = 0.005). In conclusion, we demonstrated that rs1492099, a SNP of AGTR1 gene, could be a potential genetic risk factor of AVF malfunction in male HD patients.

Circulating n-3 fatty acids and trans-fatty acids, PLA2G2A gene variation and sudden cardiac arrest

Whether genetic factors influence the associations of fatty acids with the risk of sudden cardiac arrest (SCA) is largely unknown. To investigate possible gene–fatty acid interactions on SCA risk, we used a case-only approach and measured fatty acids in erythrocyte samples from 1869 SCA cases in a population-based repository with genetic data. We selected 191 SNP in ENCODE-identified regulatory regions of fifty-five candidate genes in fatty acid metabolic pathways. Using linear regression and additive genetic models, we investigated the association of the selected SNP with erythrocyte levels of fatty acids, including DHA, EPA and trans-fatty acids among the SCA cases. The assumption of no association in non-cases was supported by analysis of publicly available datasets containing over 8000 samples. None of the SNP–fatty acid associations tested among the cases reached statistical significance after correction for multiple comparisons. One SNP, rs4654990 near PLA2G2A, with an allele frequency of 0·33, was nominally associated with lower levels of DHA and EPA and higher levels of trans-fatty acids. The strongest association was with DHA levels (exponentiated coefficient for one unit (1 % of total fatty acids), 0·90, 95 % CI 0·85, 0·97; P = 0·003), indicating that for subjects with a coded allele, the OR of SCA associated with one unit higher DHA is about 90 % what it is for subjects with one fewer coded allele. These findings suggest that the associations of circulating n-3 and trans-fatty acids with SCA risk may be more pronounced in carriers of the rs4654990 G allele.

ACE2: angiotensin II/angiotensin-(1-7) balance in cardiac and renal injury

Our current recognition of the renin-angiotensin system is more convoluted than originally thought due to the discovery of multiple novel enzymes, peptides, and receptors inherent in this interactive biochemical cascade. Over the last decade, angiotensin-converting enzyme 2 (ACE2) has emerged as a key player in the pathophysiology of hypertension and cardiovascular and renal disease due to its pivotal role in metabolizing vasoconstrictive/hypertrophic/proliferative angiotensin II into favorable angiotensin-(1-7). This review addresses the considerable advancement in research on the role of tissue ACE2 in the development and progression of hypertension and cardiac and renal injury. We summarize the results from recent clinical and experimental studies suggesting that serum or urine soluble ACE2 may serve as a novel biomarker or independent risk factor relevant for diagnosis and prognosis of cardiorenal disease. We also review recent proceedings on novel therapeutic approaches to enhance ACE2/angiotensin-(1-7) axis.

Association of CASQ2 polymorphisms with sudden cardiac arrest and heart failure in patients with coronary artery disease

BACKGROUND

Abnormal calcium handling plays a crucial role in arrhythmias, sudden cardiac arrest (SCA), and congestive heart failure (CHF). Calsequestrin 2 (CASQ2) mutations affect calcium release and initiate malignant ventricular arrhythmias (VAs) and SCA syndromes. Common single nucleotide polymorphisms (SNPs) in CASQ2 may be associated with SCA in patients with coronary artery disease (CAD).

OBJECTIVE

The purpose of this study was to examine the association of common CASQ2 SNPs with the risk of SCA in patients with CAD.

METHODS

CASQ2 SNPs (n = 14) were genotyped and analyzed in a case control study comparing 114 patients with CAD and SCA due to VA to 311 CAD controls without VA or SCA.

RESULTS

Multivariate logistic regression adjusting for age and CHF status identified an association between rs7521023 with SCA (odds ratio [OR] 2.72, 95% confidence interval [CI] 1.44-5.13, P = .002). The substantial impact of CHF on SCA in the model (OR 26.6, 95% CI 13.40-52.70, P <.001) led us to further examine the relationship between CHF, SCA, and CASQ2 SNPs. We identified 2 CASQ2 variants (rs7521023: OR 0.4, 95% CI 0.25-0.76, P = .003; rs6684209: OR 19.8, 95% CI 3.63-108.2, P <.001) associated with CHF after adjusting for SCA, age, gender, and hypertension.

CONCLUSION

We observed association between a CASQ2 polymorphism and SCA due to VA in patients with CAD adjusting for CHF and independent associations between CASQ2 SNPs and CHF adjusting for SCA. Further investigation in independent cohorts is needed to confirm these findings.

Genetic manipulation and genetic variation of the kallikrein-kinin system: impact on cardiovascular and renal diseases

Genetic manipulation of the kallikrein-kinin system (KKS) in mice, with either gain or loss of function, and study of human genetic variability in KKS components which has been well documented at the phenotypic and genomic level, have allowed recognizing the physiological role of KKS in health and in disease. This role has been especially documented in the cardiovascular system and the kidney. Kinins are produced at slow rate in most organs in resting condition and/or inactivated quickly. Yet the KKS is involved in arterial function and in renal tubular function. In several pathological situations, kinin production increases, kinin receptor synthesis is upregulated, and kinins play an important role, whether beneficial or detrimental, in disease outcome. In the setting of ischemic, diabetic or hemodynamic aggression, kinin release by tissue kallikrein protects against organ damage, through B2 and/or B1 bradykinin receptor activation, depending on organ and disease. This has been well documented for the ischemic or diabetic heart, kidney and skeletal muscle, where KKS activity reduces oxidative stress, limits necrosis or fibrosis and promotes angiogenesis. On the other hand, in some pathological situations where plasma prekallikrein is inappropriately activated, excess kinin release in local or systemic circulation is detrimental, through oedema or hypotension. Putative therapeutic application of these clinical and experimental findings through current pharmacological development is discussed in the chapter.

Genetics of sudden cardiac death caused by ventricular arrhythmias

Sudden cardiac death (SCD) resulting from ventricular tachyarrhythmia is a major contributor to mortality. Clinical management of SCD, currently based on clinical markers of SCD risk, can be improved by integrating genetic information. The identification of multiple disease-causing gene variants has already improved patient management and increased our understanding of the rare Mendelian diseases associated with SCD risk in the young, but marked variability in disease severity suggests that additional genetic modifiers exist. Next-generation DNA sequencing could be crucial to the discovery of SCD-associated genes, but large data sets can be difficult to interpret. SCD usually occurs in patients with an average age of 65 years who have complex cardiac disease stemming from multiple, common, acquired disorders. Heritable factors are largely unknown, but are likely to have a role in determining the risk of SCD in these patients. Numerous genetic loci have been identified that affect electrocardiogram indices, which are regarded as intermediate phenotypes for tachyarrhythmia. These loci could help to identify new molecules and pathways affecting cardiac electrical function. These loci are often located in intergenic regions, so our evolving understanding of the noncoding regulatory regions of the genome are likely to aid in the identification of novel genes that are important for cardiac electrical function and possibly SCD.

Nitric Oxide Synthase 1 Adaptor Protein, an Emerging New Genetic Marker for QT Prolongation and Sudden Cardiac Death

Sudden cardiac death (SCD) is defined as sudden unexplained death due to cardiac causes with an acute change in cardiovascular status within 1 hour of onset of symptoms. Alternatively, in unwitnessed cases, SCD can also be defined as a person last seen functionally normal 24 hours before being found dead. Despite significant advances in understanding the pathophysiology of cardiovascular diseases and the resultant improvement in resuscitation science, SCD remains a major healthcare challenge worldwide. Although the most pronounced risk factor for SCD is the presence of coronary artery disease in the setting of a depressed left ventricular function, most deaths occur in the larger, lower-risk subgroups where genetic variations and other conditions may be the precipitating factors in triggering SCD. Recently, a common genetic variation in a neuronal nitric oxide synthase regulator, nitric oxide synthase 1 adaptor protein (NOS1AP) also known as carboxyl-terminal PDZ ligand of neuronal nitric oxide synthase protein (CAPON) gene, has been identified as a new genetic marker in modulating QT interval prolongation and SCD in general populations. Animal study revealed that NOS1AP is expressed in the heart and interacts with NOS1-NO pathways to modulate cardiac repolarization via suppressing the sarcolemmal L-type calcium current and enhancing the IKr current. This important genetic implication was soon replicated in other racial/ethnic populations and extended to a variety of clinical settings including diabetes mellitus, coronary artery disease, myocardial infarction, and congenital or drug-induced long QT syndrome. The purpose of this review aims to provide up-to-date information about the emerging new genetic marker, NOS1AP, in relation to QT prolongation and SCD.

KEY WORDS

NOS1AP; QT interval; Sudden cardiac death.

[Molecular and genetic background of sudden cardiac death]

Despite recent findings on the functional, structural and genetic background of sudden cardiac death, the incidence is still relatively high in the entire population. A thorough knowledge on susceptibility, as well as pathophysiology behind the development of malignant arrhythmias will help us to identify individuals at risk and prevent sudden cardiac death. This article presents a review of the current literature on the role of altered intracellular Ca2+ handling, acute myocardial ischaemia, cardiac autonomic innervation, renin-angiotensin-aldosterone system, monogenic and complex heritability in the pathogenesis of sudden cardiac death.

The ACE2 gene: its potential as a functional candidate for cardiovascular disease

The RAS (renin–angiotensin system) plays an important role in the pathophysiology of CVD (cardiovascular disease), and RAS blockade is an important therapeutic strategy in the management of CVD. A new counterbalancing arm of the RAS is now known to exist in which ACE (angiotensin-converting enzyme) 2 degrades Ang (angiotensin) II, the main effector of the classic RAS, and generates Ang-(1–7). Altered ACE2 expression is associated with cardiac and vascular disease in experimental models of CVD, and ACE2 is increased in failing human hearts and atherosclerotic vessels. In man, circulating ACE2 activity increases with coronary heart disease, as well as heart failure, and a large proportion of the variation in plasma ACE2 levels has been attributed to hereditary factors. The ACE2 gene maps to chromosome Xp22 and this paper reviews the evidence associating ACE2 gene variation with CVD and considers clues to potential functional ACE2 variants that may alter gene expression or transcriptional activity. Studies to date have investigated ACE2 gene associations in hypertension, left ventricular hypertrophy and coronary artery disease, but the results have been inconsistent. The discrepancies may reflect the sample size of the studies, the gender or ethnicity of subjects, the cardiovascular phenotype or the ACE2 SNP investigated. The frequent observation of apparent sex-dependence might be of special importance, if confirmed. As yet, there are no studies to concurrently assess ACE2 gene polymorphisms and circulating ACE2 activity. Large-scale carefully conducted clinical studies are urgently needed to clarify more precisely the potential role of ACE2 in the CVD continuum.

Angiotensin converting enzyme DD genotype is associated with acute coronary syndrome severity and sudden cardiac death in Taiwan: a case-control emergency room study

Background

Angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphisms have been associated with acute coronary syndrome (ACS); however, several controversial results have also been found in different studied populations. This hospital-based, emergency room, case-control study in Taiwan retrospectively investigated 111 ACS patients, and 195 non-coronary subjects as a control group, to study the effects of ACE I/D polymorphism in the most urgent ACS patients. ACE I/D polymorphisms were determined by polymerase chain reaction-based assays and their associations with ACS risk, severity, and sudden cardiac death were determined.

Results

The ACE DD genotype was associated with ACS incidence. The DD genotype was associated with a significant 4-fold higher risk of ACS in multivariate analysis (odds ratio (OR) = 4.295; 95% confidence interval (CI): 1.436-12.851, p = 0.009), and a 3.35-fold higher risk of acute myocardial infarction. DD genotype carriers also had more than 3-fold higher risks of stenosis in all the three coronary arteries, left anterior descending artery infarction, and anterior wall infarction. In addition, the DD genotype was also associated with a higher risk of sudden cardiac death (OR = 6.484, 95% CI: 1.036-40.598, p = 0.046).

Conclusions

This study demonstrated that the ACE DD genotype is an independent risk factor for ACS, and in particular, for acute myocardial infarction. In addition, the ACE DD genotype is also associated with greater ACS severity and a higher risk of sudden cardiac death. ACE genotyping is recommended for patients with a history of ACS, and more intensive preventive care is suggested for patients with the DD genotype.

GWAS for discovery and replication of genetic loci associated with sudden cardiac arrest in patients with coronary artery disease

BACKGROUND

Epidemiologic evidence suggests a heritable component to risk for sudden cardiac arrest independent of risk for myocardial infarction. Recent candidate gene association studies for community sudden cardiac arrests have focused on a limited number of biological pathways and yielded conflicting results. We sought to identify novel gene associations for sudden cardiac arrest in patients with coronary artery disease by performing a genome-wide association study.

METHODS

Tagging SNPs (n = 338,328) spanning the genome were typed in a case-control study comparing 89 patients with coronary artery disease and sudden cardiac arrest due to ventricular tachycardia or ventricular fibrillation to 520 healthy controls.

RESULTS

Fourteen SNPs including 7 SNPs among 7 genes (ACYP2, AP1G2, ESR1, DGES2, GRIA1, KCTD1, ZNF385B) were associated with sudden cardiac arrest (all p < 1.30 × 10(-7)), following Bonferroni correction and adjustment for population substructure, age, and sex; genetic variation in ESR1 (p = 2.62 × 10(-8); Odds Ratio [OR] = 1.43, 95% confidence interval [CI]:1.277, 1.596) has previously been established as a risk factor for cardiovascular disease. In tandem, the role of 9 genes for monogenic long QT syndrome (LQT1-9) was assessed, yielding evidence of association with CACNA1C (LQT8; p = 3.09 × 10(-4); OR = 1.18, 95% CI:1.079, 1.290). We also assessed 4 recently published gene associations for sudden cardiac arrest, validating NOS1AP (p = 4.50 × 10(-2), OR = 1.15, 95% CI:1.003, 1.326), CSMD2 (p = 6.6 × 10(-3), OR = 2.27, 95% CI:1.681, 2.859), and AGTR1 (p = 3.00 × 10(-3), OR = 1.13, 95% CI:1.042, 1.215).

CONCLUSION

We demonstrate 11 gene associations for sudden cardiac arrest due to ventricular tachycardia/ventricular fibrillation in patients with coronary artery disease. Validation studies in independent cohorts and functional studies are required to confirm these associations.

Advances in the renin angiotensin system focus on angiotensin-converting enzyme 2 and angiotensin-(1-7)

The contribution of the renin angiotensin system to physiology and pathology is undergoing a rapid reconsideration of its mechanisms from emerging new concepts implicating angiotensin-converting enzyme 2 and angiotensin-(1-7) as new elements negatively influencing the vasoconstrictor, trophic, and pro-inflammatory actions of angiotensin II. This component of the system acts to oppose the vasoconstrictor and proliferative effects on angiotensin II through signaling mechanisms mediated by the mas receptor. In addition, a reduced expression of the vasodepressor axis composed by angiotensin-converting enzyme 2 and angiotensin-(1-7) may contribute to the expression of essential hypertension, the remodeling of heart and renal function associated with this disease, and even the physiology of pregnancy and the development of eclampsia.