Ile164 variant of beta2-adrenoceptor does not influence outcome in heart failure but may interact with beta blocker treatment

Pharmacogenomics of heart failure: a systematic review

BACKGROUND

Heart failure (HF) and multiple HF-related phenotypes are heritable. Genes implicated in the HF pathophysiology would be expected to influence the response to treatment.

METHODS

We conducted a series of systematic literature searches on the pharmacogenetics of HF therapy to assess the current knowledge on this field.

RESULTS

Existing data related to HF pharmacogenomics are still limited. The ADRB1 gene is a likely candidate to predict response to β-blockers. Moreover, the cytochrome P450 2D6 coding gene (CYP2D6) clearly affects the pharmacokinetics of metoprolol, although the clinical impact of this association remains to be established.

CONCLUSION

Given the rising prevalence of HF and related costs, a more personalized use of HF drugs could have a remarkable benefit for patients, caregivers and healthcare systems.

Genetic polymorphisms associated with heart failure: A literature review

Objective

To review possible associations reported between genetic variants and the risk, therapeutic response and prognosis of heart failure.

Methods

Electronic databases (PubMed, Web of Science and CNKI) were systematically searched for relevant papers, published between January 1995 and February 2015.

Results

Eighty-two articles covering 29 genes and 39 polymorphisms were identified.

Conclusion

Genetic association studies of heart failure have been highly controversial. There may be interaction or synergism of several genetic variants that together result in the ultimate pathological phenotype for heart failure.

Pharmacogenomics of heart failure

The combination of angiotensin-converting enzyme (ACE) inhibitors and β-adrenergic receptor (βAR) blockers remains the essential component of heart failure (HF) pharmacotherapy. However, individual patient responses to these pharmacotherapies vary widely. The variability in response cannot be explained entirely by clinical characteristics, and genetic variation may play a role. The purpose of this chapter is to examine the current knowledge in the field of beta-blocker and ACE inhibitor pharmacogenetics in HF. β-blocker and ACE inhibitor pharmacogenetic studies performed in patients with HF were identified from the PubMed database from 1966 to July 2011. Thirty beta-blocker and 10 ACE inhibitor pharmacogenetic studies in patients with HF were identified.The ACE deletion variant was associated with greater survival benefit from ACE inhibitors and beta-blockers compared with the ACE insertion. Ser49 in the β1AR, the insertion in the α2CAR, and Gln41 in G protein-coupled receptor (GPCR) kinase (GRK)-5 are associated with greater survival benefit from β-blockers, compared with Gly49, the deletion, and Leu41, respectively. However, many of these associations have not been validated. The HF pharmacogenetic literature is still in its very early stages, but there are promising candidate genetic variants that may identify which HF patients are most likely to benefit from beta-blockers and ACE inhibitors and patients that may require additional therapies.

A novel approach to drug development in heart failure: towards personalized medicine

Evidence-based treatment has succeeded in improving clinical outcomes in heart failure. Nevertheless, morbidity, mortality, and the economic burden associated with the syndrome remain unsatisfactorily high. Most landmark heart failure studies included broad study populations, and thus current recommendations dictate standardized, universal therapy. While most patients included in recent trials benefit from this background treatment, exceeding this already significant gain has proven to be a challenge. The early identification of responders and nonresponders to treatment could result in improved therapeutic effectiveness, while reduction of unnecessary exposure may limit harmful and unpleasant side effects. In this review, we examine the potential value of currently available information on differential responses to heart failure therapy-a first step toward personalized medicine in the management of heart failure.

Genetic prediction of heart failure incidence, prognosis and beta-blocker response

Heart failure (HF) is a widespread syndrome due to left ventricular dysfunction with high mortality, morbidity and health-care costs. Beta-blockers, together with diuretics and ACE-inhibitors or angiotensin receptor blockers, are a cornerstone of HF therapy, as they reduce mortality and morbidity. Nevertheless, their efficacy varies among patients, and genetics is likely to be one of the modifying factors. In this article, literature on the role of candidate genes on the development of HF, its prognosis and pharmacogenomics of β-blockers in patients with HF is reviewed. The available findings do not support, at the present time, a role for genetic tests in the treatment of HF. More large-scale genome-wide studies with adequate methodology and statistical analysis are required before considering genetic tailoring of HF therapy in patients with systolic HF.

Pharmacogenetics in chronic heart failure: new developments and current challenges

The individual patient responses to chronic heart failure (HF) pharmacotherapies are highly variable. This variability cannot be entirely explained by clinical characteristics, and genetic variation may play a role. Therefore, this review will summarize the background pharmacogenetic literature for major HF pharmacotherapy classes (ie, β-blockers, angiotensin-converting enzyme inhibitors, digoxin, and loop diuretics), evaluate recent advances in the HF pharmacogenetic literature in the context of previous findings, and discuss the challenges and conclusions for HF pharmacogenetic data and its clinical application.

Genetic tailoring of pharmacotherapy in heart failure: optimize the old, while we wait for something new

BACKGROUND

The combination of angiotensin-converting enzyme (ACE) inhibitors and beta-adrenergic receptor blockers remains the essential component of heart failure (HF) pharmacotherapy. However, individual patient responses to these pharmacotherapies vary widely. The variability in response cannot be explained entirely by clinical characteristics, and genetic variation may play a role. The purpose of this review is to examine our current state of understanding of beta-blocker and ACE inhibitor pharmacogenetics in HF.

METHODS AND RESULTS

Beta-blocker and ACE inhibitor pharmacogenetic studies performed in patients with HF were identified from the Pubmed database from 1966 to July 2011. Thirty beta-blocker and 10 ACE inhibitor pharmacogenetic studies in patients with HF were identified. The ACE deletion variant was associated with greater survival benefit from ACE inhibitors and beta-blockers compared with the ACE insertion. Ser49 in the beta-1 adrenergic receptor, the insertion in the alpha-2C adrenergic receptor, and Gln41 in G-protein-coupled receptor kinase 5 are associated with greater survival benefit from beta-blockers, compared with Gly49, the deletion, and Leu41, respectively. However, many of these associations have not been validated.

CONCLUSIONS

The HF pharmacogenetic literature is still in its very early stages, but there are promising candidate genetic variants that may identify which HF patients are most likely to benefit from beta-blockers and ACE inhibitors and patients that may require additional therapies.

A systematic review on pharmacogenetics in cardiovascular disease: is it ready for clinical application?

Pharmacogenetics is the search for heritable genetic polymorphisms that influence responses to drug therapy. The most important application of pharmacogenetics is to guide choosing agents with the greatest potential of efficacy and smallest risk of adverse drug reactions. Many studies focusing on drug-gene interactions have been published in recent years, some of which led to adaptation of FDA recommendations, indicating that we are on the verge of the clinical application of genetic information in drug therapy. This systematic review provides a comprehensive overview of the current knowledge on pharmacogenetics of all major drug classes currently used in the treatment of cardiovascular diseases.

The genomic architecture of sporadic heart failure

Common or sporadic systolic heart failure (heart failure) is the clinical syndrome of insufficient forward cardiac output resulting from myocardial disease. Most heart failure is the consequence of ischemic or idiopathic cardiomyopathy. There is a clear familial predisposition to heart failure, with a genetic component estimated to confer between 20% and 30% of overall risk. The multifactorial etiology of this syndrome has complicated identification of its genetic underpinnings. Until recently, almost all genetic studies of heart failure were designed and deployed according to the common disease-common variant hypothesis, in which individual risk alleles impart a small positive or negative effect and overall genetic risk is the cumulative impact of all functional genetic variations. Early studies used a candidate gene approach focused mainly on factors within adrenergic and renin-angiotensin pathways that affect heart failure progression and are targeted by standard pharmacotherapeutics. Many of these reported allelic associations with heart failure have not been replicated. However, the preponderance of data supports risk-modifier effects for the Arg389Gly polymorphism of β1-adrenergic receptors and the intron 16 in/del polymorphism of angiotensin-converting enzyme. Recent unbiased studies using genome-wide single nucleotide polymorphism microarrays have shown fewer positive results than when these platforms were applied to hypertension, myocardial infarction, or diabetes, possibly reflecting the complex etiology of heart failure. A new cardiovascular gene-centric subgenome single nucleotide polymorphism array identified a common heat failure risk allele at 1p36 in multiple independent cohorts, but the biological mechanism for this association is still uncertain. It is likely that common gene polymorphisms account for only a fraction of individual genetic heart failure risk, and future studies using deep resequencing are likely to identify rare gene variants with larger biological effects.

Adrenergic signaling polymorphisms and their impact on cardiovascular disease

This review examines the impact of recent discoveries defining personal genetics of adrenergic signaling polymorphisms on scientific discovery and medical practice related to cardiovascular diseases. The adrenergic system is the major regulator of minute-by-minute cardiovascular function. Inhibition of adrenergic signaling with pharmacological beta-adrenergic receptor antagonists (beta-blockers) is first-line therapy for heart failure and hypertension. Advances in pharmacology, molecular biology, and genetics of adrenergic signaling pathways have brought us to the point where personal genetic differences in adrenergic signaling factors are being assessed as determinants of risk or progression of cardiovascular disease. For a few polymorphisms, functional data generated in cell-based systems, genetic mouse models, and pharmacological provocation of human subjects are concordant with population studies that suggest altered risk of cardiovascular disease or therapeutic response to beta-blockers. For the majority of adrenergic pathway polymorphisms however, published data conflict, and the clinical relevance of individual genotyping remains uncertain. Here, the current state of laboratory and clinical evidence that adrenergic pathway polymorphisms can affect cardiovascular pathophysiology is comprehensively reviewed and compared, with a goal of placing these data in the broad context of potential clinical applicability.

RAAS and adrenergic genes in heart failure: Function, predisposition and survival implications

It is well appreciated that several neurohormones and signaling cascades are activated that promote long-term deterioration of cardiac function and structure. Activation of the renin-angiotensin-aldosterone system (RAAS) and the adrenergic system is closely related to heart failure. Common gene variants that encode neurohormonal, adrenergic and intracellular proteins have been demonstrated to modulate the course and consequences of heart failure. However, the literature is replete with conflicting results and it remains uncertain as to whether particular gene variants predispose heart failure. Therefore, the main purpose of this review was to discuss the effects of single nucleotide polymorphisms (SNPs) that are located in genes encoding elements of the RAAS and the adrenergic system on the predisposition to and survival from heart failure. Most studies indicate that common SNPs encoding elements of the RAAS and the adrenergic system do not predispose individuals to heart failure. Conversely, it has been demonstrated that ARB1 Arg389Gly, GRK5 Gln41Leu, ACE I/D, CYP11B2 C-344T and AGTR1 A+1166C modulate pharmacological responses and have a considerable impact on cardiac-related survival. It should not be expected, however, that a single polymorphism determines survival, given that multiple gene products and environmental factors contribute to the pathogenesis of heart failure. Therefore, future studies should consider the interaction effects of multiple genes in populations that are as homogeneous as possible with respect to environmental characteristics.

Prevalence of beta-2 adrenergic receptor (beta 2 AR) polymorphisms and its influence on a model used to assess endothelial function using pulse wave analysis (PWA)

BACKGROUND

Pulse wave analysis (PWA) combined with beta(2)-agonist challenge has recently been used to assess endothelial function. beta-2 adrenergic receptor (beta(2)AR) polymorphisms may affect response to beta(2)-agonist. We determined whether beta(2)AR polymorphisms influence endothelial response in our model using PWA and salbutamol.

METHODS

388 healthy Malay subjects (177 males, 211 females) were genotyped for 5 functionally important single nucleotide polymorphisms (SNPs) of beta(2)AR; 298 subjects proceeded with assessment of endothelial function. The parameter augmentation index (AIx) was recorded non-invasively using SphygmoCor. Recording of AIx at baseline was followed by administration of 500 microg sublingual glyceryl trinitrate (GTN). AIx recordings were repeated at 3, 5, 10, 15 and 20 min post-GTN. Subjects then inhaled 400 microg of salbutamol before AIx recordings at 5 min intervals up to 20 min. Maximum changes in AIx after GTN and salbutamol represented endothelium independent and endothelium dependent vasodilatation (EDV) respectively.

RESULTS

Allele frequencies of mutated Gly16, Glu27, Ile164, -20C and -47C were 47%, 6.8%, 0%, 30% and 9.3% respectively. No significant differences in EDV were noted between genotype groups of each studied SNPs.

CONCLUSIONS

Assessment of endothelial function using PWA and salbutamol was not influenced by beta(2)AR polymorphisms.