R46L polymorphism in the PCSK9 gene: Relationship to lipid levels, subclinical vascular disease, and erectile dysfunction

Effect of the PCSK9 R46L genetic variant on plasma insulin and glucose levels, risk of diabetes mellitus and cardiovascular disease: A meta-analysis

BACKGROUND AND AIM

The impact of the loss-of-function (LOF) genetic variant PCSK9 R46L on glucose homeostasis and cardiovascular disease (CVD) remains uncertain, despite its established correlation with diminished blood cholesterol levels. This meta-analysis aimed at exploring the effect of the PCSK9 R46L genetic variant on plasma insulin and glucose levels, risk of diabetes mellitus and CVD.

METHODS AND RESULTS

PubMed, Embase, and the Cochrane Library were searched for cohort and case-control studies published until October 1, 2023. The studies should report the association of the PCSK9 R46L genetic variant with one of the following: fasting plasma insulin, blood glucose levels, diabetes mellitus, and CVD risk. A dominant model of the PCSK9 R46L genetic variant was employed to statistical analysis. The meta-analyses were performed for continuous variables with standard mean difference (SMD), categorical variables with odds ratio (OR) using a random-effects model. A total of 17 articles with 20 studies engaging 1,186,861 population were identified and mobilized for these analyses. The overall results indicated that, compared with non-carriers of the PCSK9 R46L genetic variant, carriers of the PCSK9 R46L genetic variant did not increase or decrease the levels of fasting plasma insulin (3 studies with 7277 population; SMD, 0.08; 95% CI, -0.04 to 0.19; P = 0.270), and the levels of fasting plasma glucose (7 studies with 9331 population; SMD, 0.03; 95% CI, -0.08 to 0.13; P = 0.610). However, carriers of the PCSK9 R46L genetic variant indeed had 17% reduction in the risk of CVD (11 studies with 558,263 population; OR, 0.83; 95% CI, 0.71 to 0.98; P = 0.030), and 9% increase in the risk of diabetes mellitus (10 studies with 744,466 population; OR, 1.09; 95% CI, 1.04 to 1.14; P < 0.01). Meta-regression analyses indicated that the increased risk of diabetes mellitus and the reduced risk of CVD were positively correlated with reduction in LDL-C (P = 0.004 and 0.033, respectively).

CONCLUSIONS

PCSK9 R46L genetic variant exhibited an elevated susceptibility to diabetes mellitus alongside a reduced vulnerability to CVD.

Genetic association of lipid-lowering drug target genes with erectile dysfunction and male reproductive health

Objective

The effect of hypolipidemic drugs on male erectile function is still controversial. This Mendelian randomization (MR) study aimed to explore the potential impact of lipid-lowering drug targets on ED.

Methods

We collected seven genetic variants encoding lipid-lowering drug targets (LDLR, HMGCR, NPC1L1, PCSK9, APOB, APOC3 and LPL) from published genome-wide association study (GWAS) statistics, and performed drug target MR analysis. The risk of ED was defined as the primary outcome, sex hormone levels and other diseases as the secondary outcomes. Mediation analyses were performed to explore potential mediating factors.

Results

The results showed that LDLR, LPL agonists and APOC3 inhibitors were significantly associated with a reduced risk of ED occurrence. APOB inhibitors were associated with an increased risk of ED occurrence. In terms of sex hormone levels, LDLR and LPL agonists were significantly associated with increased TT levels, and HMGCR was associated with decreased TT and BT levels significantly. In terms of male-related disease, MR results showed that LDLR agonists and PCSK9 inhibitors were significantly associated with an elevated risk of PH; HMGCR, NPC1L1 inhibitors were associated with a reduced risk of PCa; and LDLR agonists were significantly associated with a reduced risk of AS and MI; in addition, HMGCR inhibitors were associated with a reduced risk of PCa.

Conclusion

After performing drug-targeted MR analysis, we found that that there was a causal relationship between lipid-lowering drug targets and ED. APOC3, APOB, LDLR and LPL may be new candidate drug targets for the treatment of ED.

Correlations of PCSK9 and LDLR Gene Polymorphisms and Serum PCSK9 Levels With Atherosclerosis and Lipid Metabolism in Patients on Maintenance Hemodialysis

This study is aimed at investigating the correlations of PCSK9 and LDLR gene polymorphisms as well as serum proprotein convertase subtilisin/kexin type 9 (PCSK9) levels with atherosclerosis and lipid metabolism in patients on maintenance hemodialysis (HD). A single nucleotide polymorphism at the E670G locus of the PCSK9 gene and the rs688 locus of the LDLR gene was analyzed by polymerase chain reaction-restriction fragment length polymorphism. All study subjects' blood lipid (triglyceride [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]) concentrations and lipoprotein(a) and PCSK9 levels were measured. The differences in blood lipid levels between different genotypes of the E670G locus of the PCSK9 gene and the rs688 locus of the LDLR gene in patients on maintenance HD with atherosclerosis were compared. Patients on maintenance HD with atherosclerosis at the E670G locus of the PCSK9 gene AG + GG genotype had higher levels of TG, TC, LDL-C, and lipoprotein(a) than the AA genotype, and lower levels of HDL-C than the AA genotype. Patients on maintenance HD with atherosclerosis at the rs688 locus of the LDLR gene CT + TT genotype had higher levels of TG, TC, LDL-C, and lipoprotein(a) than the CC genotype, and lower levels of HDL-C than the CC genotype. Serum PCSK9 contents in patients on maintenance HD with atherosclerosis were positively correlated with lipid indices (TG, TC, LDL-C, and lipoprotein(a)) and carotid ultrasound indices (intima-media thickness and resistance index), and negatively correlated with HDL-C, maximum systolic blood flow velocity, and minimum diastolic blood flow velocity (all P < .05).

Increased Carotid Intima-Media Thickness in Asymptomatic Individuals Is Associated with the PCSK9 (rs2149041) Gene Polymorphism in the Mexican Mestizo Population: Results of the GEA Cohort

The increase in carotid intima-media thickness (CIMT) and coronary artery calcification (CAC) are features of subclinical atherosclerosis that might be determined by the genetic background of patients. Among the multiple risk factors, the proprotein convertase subtilisin kexin type 9 (PCSK9) has a great impact on atheroma development. Then, we focused on the potential association of the PCSK9 gene polymorphism (rs2149041) with the risk of an increased CIMT. We included 881 unrelated, asymptomatic individuals (732 normal CIMT and 149 increased CIMT) who lacked coronary calcification (CAC score = 0). Under the recessive inheritance model and adjusted by several cardiovascular risk factors, the rs2149041 polymorphism, determined by TaqMan genotyping assay, was associated with a high risk of increased CIMT (OR = 2.10, 95% IC = 1.26–3.47, P recessive = 0.004). Our results suggest that the rs2149041 polymorphism could be a risk marker for increased CIMT in asymptomatic individuals without coronary artery disease determined by the absence of a CAC score.

PCSK9: A Multi-Faceted Protein That Is Involved in Cardiovascular Biology

Pro-protein convertase subtilisin/kexin type 9 (PCSK9) is secreted mostly by hepatocytes and to a lesser extent by the intestine, pancreas, kidney, adipose tissue, and vascular cells. PCSK9 has been known to interact with the low-density lipoprotein receptor (LDLR) and chaperones the receptor to its degradation. In this manner, targeting PCSK9 is a novel attractive approach to reduce hyperlipidaemia and the risk for cardiovascular diseases. Recently, it has been recognised that the effects of PCSK9 in relation to cardiovascular complications are not only LDLR related, but that various LDLR-independent pathways and processes are also influenced. In this review, the various LDLR dependent and especially independent effects of PCSK9 on the cardiovascular system are discussed, followed by an overview of related PCSK9-polymorphisms and currently available and future therapeutic approaches to manipulate PCSK9 expression.

Effect of PCSK9 E670G and R46L Polymorphisms on Major Adverse Cardio-Cerebrovascular Events in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

Major adverse cardio-cerebrovascular events (MACCE) in ST-segment elevation myocardial infarction (STEMI) are still high, although there have been advances in pharmacology and interventional procedures. Proprotein convertase subtilisin/Kexin type 9 ( PCSK9 ) is a serine protease regulating lipid metabolism associated with inflammation in acute coronary syndrome. The MACCE is possibly related to polymorphisms in PCSK9 . A prospective cohort observational study was designed to confirm the association between polymorphism of E670G and R46L in the PCSK9 gene with MACCE in STEMI. The Cox proportional hazards model and Spearman correlation were utilized in the study. The Genotyping of PCSK9 and ELISA was assayed. Sixty-five of 423 STEMI patients experienced MACCE in 6 months. The E670G polymorphism in PCSK9 was associated with MACCE (hazard ratio = 45.40; 95% confidence interval: 5.30-390.30; p  = 0.00). There was a significant difference of PCSK9 plasma levels in patients with previous statin consumption (310 [220-1,220] pg/mL) versus those free of any statins (280 [190-1,520] pg/mL) ( p  = 0.001). E670G polymorphism of PCSK9 was associated with MACCE in STEMI within a 6-month follow-up. The plasma PCSK9 level was higher in statin users.

PCSK9 genetic (rs11591147) and epigenetic (DNA methylation) modifications associated with PCSK9 expression and serum proteins in CAD patients

INTRODUCTION

Proprotein convertase subtilisin/kexin type 9 (PCSK9) genetic polymorphisms play a significant role in cholesterol homeostasis. Therefore, we aimed to investigate the association of PCSK9 genetic variations NM_174936.3:c.137G>T (R46L, rs11591147) and NM_174936.3:c.1120G>T (D374Y, rs137852912), as well as promoter DNA methylation status, with mRNA expression and circulating serum protein levels in coronary artery disease (CAD) patients.

METHODS

The present study includes 300 CAD cases and 300 controls from South India. Biochemical assays were performed using commercially available kits. PCSK9 rs11591147 and rs137852912 polymorphisms were analyzed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism method, whereas promoter DNA methylation status and gene expression were determined using methylation specific PCR and quantitative PCR respectively.

RESULTS

The genotypic distribution of PCSK9 rs11591147 revealed that individuals with the TT-genotype and T-allele have a reduced risk for CAD. Furthermore, patients with the PCSK9 rs11591147 TT genotype have a significantly lower total cholesterol and low-density lipoprotein-cholesterol levels and also higher high-density lipoprotein-cholesterol levels than individuals with the GG genotype. Logistic regression analysis has shown that the GG and GT (p = 1.51 × 10^-8 , p = 1.47 × 10^-9 ) genotypes predicted the risk for CAD with an odds ratio of 5.8 and 7.3 respectively. In addition, individuals with the TT genotype were hypermethylated at promoter DNA of PCSK9, resulting in lower mRNA expression and circulating serum proteins than in individuals with the GG genotype. In silico analyses revealed that rs11591147 T-allele has protein destabilizing capacity.

CONCLUSIONS

In conclusion, the present study indicates that the PCSK9 gene expression and circulating serum protein levels are not only associated with rs11591147 genotype, but also with promoter DNA methylation. Furthermore, the findings with respect to both single nucleotide polymorphism and promoter DNA methylation may open avenues for novel treatment possibilities targeting PCSK9 for CAD management.

Variants of PCSK9 Gene Are Associated with Subclinical Atherosclerosis and Cardiometabolic Parameters in Mexicans. The GEA Project

Background: Coronary artery disease (CAD) is a chronic, inflammatory, and complex disease associated with vascular risk factors. Nowadays, the coronary artery calcium (CAC) is a specific marker of the presence and extent of atherosclerosis. Additionally, CAC is a predictor of future coronary events in asymptomatic individuals diagnosed with subclinical atherosclerosis (CAC > 0). In this study, our aim is to evaluate the participation of two polymorphisms of the PCSK9 gene as genetic markers for developing subclinical atherosclerosis and cardiometabolic risk factors in asymptomatic individuals. Methods: We analyzed two PCSK9 polymorphisms (rs2479409 and rs615563) in 394 individuals with subclinical atherosclerosis and 1102 healthy controls using real time- polymerase chain reaction (PCR). Results: Under various inheritance models adjusted for different confounding factors, the rs2479409 polymorphism was associated with an increased risk of developing subclinical atherosclerosis (OR = 1.53, P recessive = 0.041). Both polymorphisms were significantly associated with several cardiometabolic parameters. Conclusions: Our data suggest that rs2479409 polymorphism could be envisaged as a risk marker for subclinical atherosclerosis.

A genome-wide association study to identify candidate genes for erectile dysfunction

Erectile dysfunction (ED) can be caused by different diseases and controlled by several genetic networks. In this study, to identify the genes related to ED, the expression profiles of normal and ED samples were investigated by the Gene Expression Omnibus (GEO) database. Seventeen genes were identified as associated genes with ED. The protein and nucleic acid sequences of selected genes were retrieved from the UCSC database. Selected genes were diverse according to their physicochemical properties and functions. Category function revealed that selected genes are involved in pathways related to humans some diseases. Furthermore, based on protein interactions, genes associated with the insulin pathway had the greatest interaction with the studied genes. To identify the common cis-regulatory elements, the promoter site of the selected genes was retrieved from the UCSC database. The Gapped Local Alignment of Motifs tool was used for finding common conserved motifs into the promoter site of selected genes. Besides, INSR protein as an insulin receptor precursor showed a high potential site for posttranslation modifications, including phosphorylation and N-glycosylation. Also, in this study, two Guanine-Cytosine (GC)-rich regions were identified as conserved motifs in the upstream of studied genes which can be involved in regulating the expression of genes associated with ED. Also, the conserved binding site of miR-29-3p that is involved in various cancers was observed in the 3' untranslated region of genes associated with ED. Our study introduced new genes associated with ED, which can be good candidates for further analyzing related to human ED.

PCSK9 Variants in Familial Hypercholesterolemia: A Comprehensive Synopsis

Autosomal dominant familial hypercholesterolemia (FH) affects approximately 1/250, individuals and potentially leads to elevated blood cholesterol and a significantly increased risk of atherosclerosis. Along with improvements in detection and the increased early diagnosis and treatment, the serious burden of FH on families and society has become increasingly apparent. Since FH is strongly associated with proprotein convertase subtilisin/kexin type 9 (PCSK9), increasing numbers of studies have focused on finding effective diagnostic and therapeutic methods based on PCSK9. At present, as PCSK9 is one of the main pathogenic FH genes, its contribution to FH deserves more explorative research.

Gene Polymorphisms Affecting Erectile Dysfunction

INTRODUCTION

Erectile dysfunction (ED) is usually developed from psychological, neurological, hormonal, and vascular pathologies or a combination of these factors. However, the possible genetic polymorphisms that might underlie this disorder were not thoroughly investigated.

OBJECTIVES

This review article aimed to assess the possible involvement of gene polymorphisms in men with ED.

METHODS

A systematic review was conducted until January 2020 based on a search of all relevant articles in many electronic sites such as PubMed, Medline Medical Subject Headings, Science Direct, Scopus, Cochrane Library, EMBASE, CINAHL, and Egyptian Knowledge Bank databases with no language restriction. Keywords used to assess the outcome and estimates for relevant associations were sexual health, genes, erectile dysfunction, polymorphisms, and cavernous tissues.

RESULTS

Many genetic studies were carried out to inspect the contribution of different encoded genotypes and ED. Overall, 50 studies were reviewed and were classified as per the type of gene polymorphisms. These studies have investigated 10,174 men with ED compared with 6,891 healthy men as controls. 35 studies were case-controlled, 13 cross-sectional cohort studies, one retrospective study, and one genome-wide association study. So far, the most relevant gene polymorphisms linked with men with ED included endothelial nitric oxide synthase (eNOS), angiotensin-converting enzyme (ACE), androgen receptor (AR) CAG repeat, G-protein β3 (GNB3) subunit, methylenetetrahydrofolate reductase (MTHFR), vascular endothelial growth factor (VEGF), TGFB1, proprotein convertase subtilisin/kexin type 9 (PCSK9), ARG1, DRD2, DRD4, DDAH, and HNF4A genes. Both PROGINS and IGFBP-3 polymorphisms were investigated in only one study each but with irrelevant significance.

CONCLUSIONS

Although several genetic studies exposed the association between different genotypes and men with ED with varied outcomes, such a relationship should not be overlooked. Therefore, more studies should be encouraged to elucidate the exact role, if any, for such association. Mostafa T, Taymour M. Gene Polymorphisms Affecting Erectile Dysfunction. Sex Med 2020;8:561-572.

Cholesterol-Lowering Agents

Loss-of-function variants in PCSK9 (proprotein convertase subtilisin-kexin type 9) are associated with lower lifetime risk of atherosclerotic cardiovascular disease) events. Confirmation of these genetic observations in large, prospective clinical trials in participants with atherosclerotic cardiovascular disease has provided guidance on risk stratification and enhanced our knowledge on hitherto unresolved and contentious issues concerning the efficacy and safety of markedly lowering LDL-C (low-density lipoprotein cholesterol). PCSK9 has a broad repertoire of molecular effects. Furthermore, clinical trials with PCSK9 inhibitors demonstrate that reductions in atherosclerotic cardiovascular disease events are more effective in patients with recent myocardial infarction, multiple myocardial infarctions, multivessel coronary artery disease, and lower extremity arterial disease. The potent LDL-C lowering efficacy of PCSK9 inhibitors provides the opportunity for more aggressive LDL-lowering strategies in high-risk patients with atherosclerotic cardiovascular disease and supports the notion that there is no lower limit for LDL-C. Aggressive LDL-C lowering with fully human PCSK9 monoclonal antibodies has been associated by a safety profile superior to that of other classes of LDL-lowering agents. These clinical trials provide evidence that LDL lowering with PCSK9 inhibitors is an effective therapy for lowering cardiovascular events in high-risk patients with LDL-C levels ≥70 mg/dL on maximally tolerated oral therapies, including statins and ezetimibe.

Serum PCSK9 levels, but not PCSK9 polymorphisms, are associated with CAD risk and lipid profiles in southern Chinese Han population

Background

Genetic and environment factors affect the occurrence and development of coronary artery disease (CAD). Proprotein convertase subtilisin/kexin type 9 (PCSK9), has been investigated extensively in the field of lipid metabolism and CAD. We performed this case-control study to investigate the relationship between serum PCSK9 levels and PCSK9 polymorphisms and lipid levels and CAD risk in a southern Chinese population.

Methods

A hospital-based case-control study with 1, 096 subjects, including 626 CAD patients and 470 controls, were conducted. Genotyping of PCSK9 polymorphisms was performed using polymerase chain reaction-ligase detection reaction (PCR-LDR) method.

Results

The frequencies of the AA, AG and GG genotypes of PCSK9 E670G polymorphism were 90.58, 9.27, and 0.16% in the CAD patients, compared with 88.72, 10.85 and 0.43% in the controls, respectively. No R46L variant was detected in this population. There were no significant differences in genotype and allele frequencies of PCSK9E670G polymorphism between the CAD group and the controls. Serum lipid levels were not significantly different in carriers with the G allele and those with the AA genotype. The median (QR) of PCSK9 concentration was 1205.00 ng/l (577.28–1694.13 ng/l) in cases and 565.87 ng/l (357.17–967.50 ng/l) in controls, respectively. Compared with controls, CAD patients had significantly higher PCSK9 levels (z = 4.559, P < 0.001). After adjusting for age, gender, essential hypertension, diabetic mellitus, smoking and lipid profiles, PCSK9 levels remain significantly associated with increased CAD susceptibility (OR = 1.002, 95% CI = 1.001–1.002, P < 0.001). The correlation analyses showed that serum PCSK9 levels were positively associated with triglyceride (TG), Apo B and atherogenic index of plasma (AIP) levels in controls. No significant association between the PCSK9 E670G polymorphism and serum PCSK9 levels was observed in the CAD group and the controls.

Conclusions

The present study shows that serum PCSK9 levels, but not PCSK9 polymorphisms, are associated with CAD risk in Southern Chinese Han population, and that serum PCSK9 levels are positively associated with AIP.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0859-5) contains supplementary material, which is available to authorized users.