Genetic variants in the apolipoprotein(a) gene and coronary heart disease

Association of rs3798220 Polymorphism with Cardiovascular Incidents in Individuals with Elevated Lp(a)

Background/Objectives: Lipoprotein (a) [Lp(a)] plays a significant role in atherosclerosis and cardiovascular disease (CVD). Genetic regulation of Lp(a) involves variations in the apo(a) LPA gene, as specific polymorphisms like rs10455872 and rs3798220, both linked to higher Lp(a) levels and CVD. CVD remains the leading global cause of death, with high Lp(a) levels increasingly recognized as a significant factor in younger patients with no other CVD risk factors. We aimed to evaluate the association of LPA genetic variations with Lp(a) levels and its effect on cardiovascular risk as there are existing inconsistent findings. Methods: This case-control study included 251 subjects with a median age of 52 years (interquartile range, IQR = 17) and elevated Lp(a) levels. Cases were subjects who experienced early cardiovascular incidents (women < 65, men < 55 years old), and the control group included subjects without such history. Genotyping of LPA gene polymorphisms (rs10455872 and rs3798220) was performed, and demographic data with Lp(a) levels were collected. To evaluate the association between the LPA genotypes and the risk of cardiovascular incidents (CVI), several logistic regression models were performed. The cut-off points for Lp(a) levels were determined using diagnostic test accuracy measures. Results: The rs3798220-C allele was associated with higher Lp(a) levels (288 ± 166 nmol/L in cases vs. 189 ± 102 nmol/L in controls, p < 0.001) and myocardial infarction (53% in cases vs. 36% in controls, p = 0.036). Among cases, 28.9% carried the rs3798220-C allele, compared to 18.7% in controls. The rs10455872-G allele was slightly more prevalent in controls (34.15% vs. 29.69%) but without further significant associations. In this study, the cut-off Lp(a) value of 151 nmol/L, for patients with a positive family history of early CVD, is associated with a higher chance of developing CVI. Conclusions: This study demonstrates an association between the LPA rs3798220-C allele and higher Lp(a) levels, as well as an increased risk of early onset myocardial infarction. However, the obtained association should further be evaluated at a much larger scale.

Identification of allele-specific KIV-2 repeats and impact on Lp(a) measurements for cardiovascular disease risk

The abundance of Lp(a) protein holds significant implications for the risk of cardiovascular disease (CVD), which is directly impacted by the copy number (CN) of KIV-2, a 5.5 kbp sub-region. KIV-2 is highly polymorphic in the population and accurate analysis is challenging. In this study, we present the DRAGEN KIV-2 CN caller, which utilizes short reads. Data across 166 WGS show that the caller has high accuracy, compared to optical mapping and can further phase approximately 50% of the samples. We compared KIV-2 CN numbers to 24 previously postulated KIV-2 relevant SNVs, revealing that many are ineffective predictors of KIV-2 copy number. Population studies, including USA-based cohorts, showed distinct KIV-2 CN, distributions for European-, African-, and Hispanic-American populations and further underscored the limitations of SNV predictors. We demonstrate that the CN estimates correlate significantly with the available Lp(a) protein levels and that phasing is highly important.

Association between lipoprotein (a) and risk of atherosclerotic cardiovascular disease events among maintenance hemodialysis patients in Beijing, China: a single-center, retrospective study

BACKGROUND

Serum lipoprotein(a) [Lp(a)] is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD) in the general population, its association with ASCVD incidence in Chinese maintenance hemodialysis (MHD) patients remains unclear. We aimed to evaluate the relationship between Lp(a) levels and ASCVD incidence among MHD patients in Beijing, China.

METHODS

This retrospective, observational cohort study included MHD patients at Beijing Tongren Hospital from January 1, 2013 to December 1, 2020, and followed until December 1,2023. The primary outcome was ASCVD occurrence. Kaplan-Meier survival analysis was used to evaluate ASCVD-free survival in MHD patients, with stratification based on Lp(a) levels. Cox regression analyses were conducted to assess the association between Lp(a) levels and the occurrence of ASCVD.

RESULTS

A total of 265 patients were enrolled in the study. The median follow-up period were 71 months.78 (29.4%) participants experienced ASCVD events, and 118 (47%) patients died, with 58 (49.1%) deaths attributed to ASCVD. Spearman rank correlation analyses revealed positive correlations between serum Lp(a) levels and LDL-c levels, and negative correlations with hemoglobin, triglyceride, serum iron, serum creatinine, and albumin levels. Multivariate Cox regression analysis showed that Lp(a) levels ≥ 30 mg/L, increased age, decreased serum albumin levels, and a history of diabetes mellitus were significantly associated with ASCVD incidence.

CONCLUSIONS

This study demonstrated an independent and positive association between serum Lp(a) levels and the risk of ASCVD in MHD patients, suggesting that serum Lp(a) could potentially serve as a clinical biomarker for estimating ASCVD risk in this population.

Targeting Lipoprotein(a): Can RNA Therapeutics Provide the Next Step in the Prevention of Cardiovascular Disease?

Numerous genetic and epidemiologic studies have demonstrated an association between elevated levels of lipoprotein(a) (Lp[a]) and cardiovascular disease. As a result, lowering Lp(a) levels is widely recognized as a promising strategy for reducing the risk of new-onset coronary heart disease, stroke, and heart failure. Lp(a) consists of a low-density lipoprotein-like particle with covalently linked apolipoprotein A (apo[a]) and apolipoprotein B-100, which explains its pro-thrombotic, pro-inflammatory, and pro-atherogenic properties. Lp(a) serum concentrations are genetically determined by the apo(a) isoform, with shorter isoforms having a higher rate of particle synthesis. To date, there are no approved pharmacological therapies that effectively reduce Lp(a) levels. Promising treatment approaches targeting apo(a) expression include RNA-based drugs such as pelacarsen, olpasiran, SLN360, and lepodisiran, which are currently in clinical trials. In this comprehensive review, we provide a detailed overview of RNA-based therapeutic approaches and discuss the recent advances and challenges of RNA therapeutics specifically designed to reduce Lp(a) levels and thus the risk of cardiovascular disease.

Association of the LPA gene polymorphisms with coronary artery disease risk in the Xinjiang population of China: A case-control study

Lipoprotein(a) is a well-known independent risk factor for coronary artery disease (CAD) and primarily determined by variation in the LPA gene coding for the apolipoprotein(a) moiety. Our study purpose was to evaluate the association between the human LPA gene polymorphisms and CAD in Han and Uyghur populations in Xinjiang, China. A case-control study was conducted with 831 Han people (392 CAD patients and 439 control subjects) and 829 Uygur people (513 CAD patients and 316 control subjects). All participants were genotyped for the same 3 single nucleotide polymorphisms (rs1801693, rs6923877, and rs9364559) of the LPA gene by a Real-time PCR instrument. In CAD patients, the levels of lipoprotein(a) were significantly higher in the Han population with the C/C genotype at the rs1801693 (P = .018) and the A/A genotype at the rs9364559 (P = .029) than in the Uyghur population. The polymorphisms rs1801693, rs6923877, and rs9364559 were found to be associated with CAD in the Han population. For men, the distribution of rs1801693 in genotypes, alleles and recessive model (CC vs CT + TT) showed a significant difference (all P < .05), and the difference in recessive model was retained after adjustment for covariates (odds ratio [OR]: 0.557, 95% confidence interval [CI]: 0.355-0.874, P = .011). But the distribution of rs6923877 in genotypes and dominant model (GG vs AG + AA) showed a significant difference (both P < .05) in both men and women, and the difference was kept in dominant model after adjustment (OR: 1.473, 95% CI:1.009-2.148, P = .045). For women, a significant difference was found in the distribution of rs9364559 in the alleles and dominant model (AA vs AG + GG) (for alleles: P = .021, for dominant model: P = .025, OR: 0.560, 95% CI:0.350-0.898, P = .016) after adjustment. Polymorphisms rs1801693, rs6923877, and rs9364559 of the LPA gene are associated with CAD in the Han population in Xinjiang Uygur Autonomous Region of China.

Lack of significant associations between single nucleotide polymorphisms in LPAL2-LPA genetic region and all cancer incidence and mortality in Japanese population: The Japan public health center-based prospective study

BACKGROUND

High lipoprotein (a) level is an established cardiovascular risk, but its association with non-cardiovascular diseases, especially cancer, is controversial. Serum lipoprotein (a) levels vary widely by genetic backgrounds and are largely determined by the genetic variations of apolipoprotein (a) gene, LPA. In this study, we investigate the association between SNPs in LPA region and cancer incidence and mortality in Japanese.

METHODS

A genetic cohort study was conducted utilizing the data from 9923 participants in the Japan Public Health Center-based Prospective Study (JPHC Study). Twenty-five SNPs in the LPAL2-LPA region were selected from the genome-wide genotyped data. Cox regression analysis adjusted for the covariates and competing risks of death from other causes, were used to estimate the relative risk (hazard ratios (HR) with 95% confidence intervals (CI)) of overall and site-specific cancer incidence and mortality, for each SNP.

RESULTS

No significant association was found between SNPs in the LPAL2-LPA region and cancer incidence or mortality (overall/site-specific cancer). In men, however, HRs for stomach cancer incidence of 18SNPs were estimated higher than 1.5 (e.g., 2.15 for rs13202636, model free, 95%CI: 1.28-3.62) and those for stomach cancer mortality of 2SNPs (rs9365171, rs1367211) were estimated 2.13 (recessive, 95%CI:1.04-4.37) and 1.61 (additive, 95%CI: 1.00-2.59). Additionally, the minor allele for SNP rs3798220 showed increased death risk from colorectal cancer (CRC) in men (HR: 3.29, 95% CI:1.59 - 6.81) and decreased CRC incidence risk in women (HR: 0.46, 95%CI: 0.22-0.94). Minor allele carrier of any of 4SNPs could have risk of prostate cancer incidence (e.g., rs9365171 dominant, HR: 1.71, 95%CI: 1.06-2.77).

CONCLUSIONS

None of the 25 SNPs in the LPAL2-LPA region was found to be significantly associated with cancer incidence or mortality. Considering the possible association between SNPs in LPAL2-LPA region and colorectal, prostate and stomach cancer incidence or mortality, further analysis using different cohorts is warranted.

Association of lipoprotein (a) with coronary artery disease in a South Asian population: A case-control study

Introduction

Coronary artery disease (CAD), the leading cause of mortality worldwide, is characterised by an earlier onset and more severe disease in South Asians as compared to Western populations.

Methods

This is an observational study on 928 individuals who attended three tertiary care centres in Kerala, India from 2014-to 2017. The demographic, anthropometric, behavioural factors and the lipoprotein (Lp(a)) and cholesterol values were compared between the two groups and across disease severity. The Chi-square test was used to compare the categorical variables and independent sample t-test for the continuous variables. Multivariable logistic regression was performed to investigate the association of demographic, clinical and behavioural factors with the disease. Odds ratios are presented with a 95% confidence interval. In individuals below 50 years, two logistic regression models were compared to investigate the improvement in modelling the association of the independent factors and Lp(a) with the occurrence of the disease.

Results

We included 682 patients in the diseased group and 246 patients treated for non-coronary conditions in the control group. Those in the control group were significantly younger than in the diseased group(p<0.002). Significantly more patients were diabetic, hypertensive, tobacco users and consumers of alcohol in the diseased group. Multivariable logistic regression on data from all age groups showed that age (OR = 2.55, 95% CI 1.51–4.33, p = 0.01), diabetes (OR = 3.71, 95% CI 2.42–5.70, p = 0.01), hypertension (OR = 3.03, 95% CI 2.12–4.34, p = 0.01) and tobacco use (OR = 5.44, 95% CI 3.39–8.75, p = 0.01) are significantly associated with the disease. Lp(a) (OR = 1.22, 95% CI 0.87–1.72) increased the odds of the disease by 22% but was not statistically significant. In individuals below 50 years, Lp(a) significantly increased the likelihood of CAD (OR = 3.52, 95% CI 1.63–7.57, p = 0.01). Those with diabetes were seven times more likely to be diseased (OR = 7.06, 95% CI 2.59–19.21, p = 0.01) and the tobacco users had six times the likelihood of disease occurrence (OR = 6.38, 95% CI 2.62–15.54, p = 0.01). The median Lp(a) values showed a statistically significant increasing trend with the extent/severity of the disease in those below 50 years.

Conclusion

Age, diabetes, hypertension and tobacco use appear to be associated more with the occurrence of coronary artery disease in adults of all ages. Lipoprotein(a), cholesterol and BMI categories do not seem to be related to disease status in all ages. However, in individuals below 50 years, diabetes, tobacco use and lipoprotein (a) are significantly associated with the occurrence of the disease.

Lipoprotein(a) beyond the kringle IV repeat polymorphism: The complexity of genetic variation in the LPA gene

High lipoprotein(a) [Lp(a)] concentrations are one of the most important genetically determined risk factors for cardiovascular disease. Lp(a) concentrations are an enigmatic trait largely controlled by one single gene (LPA) that contains a complex interplay of several genetic elements with many surprising effects discussed in this review. A hypervariable coding copy number variation (the kringle IV type-2 repeat, KIV-2) generates >40 apolipoprotein(a) protein isoforms and determines the median Lp(a) concentrations. Carriers of small isoforms with up to 22 kringle IV domains have median Lp(a) concentrations up to 5 times higher than those with large isoforms (>22 kringle IV domains). The effect of the apo(a) isoforms are, however, modified by many functional single nucleotide polymorphisms (SNPs) distributed over the complete range of allele frequencies (<0.1% to >20%) with very pronounced effects on Lp(a) concentrations. A complex interaction is present between the apo (a) isoforms and LPA SNPs, with isoforms partially masking the effect of functional SNPs and, vice versa, SNPs lowering the Lp(a) concentrations of affected isoforms. This picture is further complicated by SNP-SNP interactions, a poorly understood role of other polymorphisms such as short tandem repeats and linkage structures that are poorly captured by common R² values. A further layer of complexity derives from recent findings that several functional SNPs are located in the KIV-2 repeat and are thus not accessible to conventional sequencing and genotyping technologies. A critical impact of the ancestry on correlation structures and baseline Lp(a) values becomes increasingly evident.

This review provides a comprehensive overview on the complex genetic architecture of the Lp(a) concentrations in plasma, a field that has made tremendous progress with the introduction of new technologies. Understanding the genetics of Lp(a) might be a key to many mysteries of Lp(a) and booster new ideas on the metabolism of Lp(a) and possible interventional targets.

Lipoprotein(a): Knowns, unknowns and uncertainties

Over the last 10 years, there have been advances on several aspects of lipoprotein(a) which are reviewed in the present article. Since the standard immunoassays for measuring lipoprotein(a) are not fully apo(a) isoform-insensitive, the application of an LC-MS/MS method for assaying molar concentrations of lipoprotein(a) has been advocated. Genome wide association, epidemiological, and clinical studies have established high lipoprotein(a) as a causal risk factor for atherosclerotic cardiovascular diseases (ASCVD). However, the relative importance of molar concentration, apo(a) isoform size or variants within the LPA gene is still controversial. Lipoprotein(a)-raising single nucleotide polymorphisms has not been shown to add on value in predicting ASCVD beyond lipoprotein(a) concentrations. Although hyperlipoproteinemia(a) represents an important confounder in the diagnosis of familial hypercholesterolemia (FH), it enhances the risk of ASCVD in these patients. Thus, identification of new cases of hyperlipoproteinemia(a) during cascade testing can increase the identification of high-risk individuals. However, it remains unclear whether FH itself increases lipoprotein(a). The ASCVD risk associated with lipoprotein(a) seems to follow a linear gradient across the distribution, regardless of racial subgroups and other risk factors. The inverse association with the risk of developing type 2 diabetes needs consideration as effective lipoprotein(a) lowering therapies are progressing towards the market. Considering that Mendelian randomization analyses have identified the degree of lipoprotein(a)-lowering that is required to achieve ASCVD benefit, the findings of the ongoing outcome trial with pelacarsen will clarify whether dramatically lowering lipoprotein(a) levels can reduce the risk of ASCVD.

Genetic testing in ambulatory cardiology clinics reveals high rate of findings with clinical management implications

PURPOSE

Cardiovascular disease (CVD) is the leading cause of death in adults in the United States, yet the benefits of genetic testing are not universally accepted.

METHODS

We developed the "HeartCare" panel of genes associated with CVD, evaluating high-penetrance Mendelian conditions, coronary artery disease (CAD) polygenic risk, LPA gene polymorphisms, and specific pharmacogenetic (PGx) variants. We enrolled 709 individuals from cardiology clinics at Baylor College of Medicine, and samples were analyzed in a CAP/CLIA-certified laboratory. Results were returned to the ordering physician and uploaded to the electronic medical record.

RESULTS

Notably, 32% of patients had a genetic finding with clinical management implications, even after excluding PGx results, including 9% who were molecularly diagnosed with a Mendelian condition. Among surveyed physicians, 84% reported medical management changes based on these results, including specialist referrals, cardiac tests, and medication changes. LPA polymorphisms and high polygenic risk of CAD were found in 20% and 9% of patients, respectively, leading to diet, lifestyle, and other changes. Warfarin and simvastatin pharmacogenetic variants were present in roughly half of the cohort.

CONCLUSION

Our results support the use of genetic information in routine cardiovascular health management and provide a roadmap for accompanying research.

Lipoprotein(a) and Cardiovascular Disease

BACKGROUND

High lipoprotein(a) concentrations present in 10%-20% of the population have long been linked to increased risk of ischemic cardiovascular disease. It is unclear whether high concentrations represent an unmet medical need. Lipoprotein(a) is currently not a target for treatment to prevent cardiovascular disease.

CONTENT

The present review summarizes evidence of causality for high lipoprotein(a) concentrations gained from large genetic epidemiologic studies and discusses measurements of lipoprotein(a) and future treatment options for high values found in an estimated >1 billion individuals worldwide.

SUMMARY

Evidence from mechanistic, observational, and genetic studies support a causal role of lipoprotein(a) in the development of cardiovascular disease, including coronary heart disease and peripheral arterial disease, as well as aortic valve stenosis, and likely also ischemic stroke. Effect sizes are most pronounced for myocardial infarction, peripheral arterial disease, and aortic valve stenosis where high lipoprotein(a) concentrations predict 2- to 3-fold increases in risk. Lipoprotein(a) measurements should be performed using well-validated assays with traceability to a recognized calibrator to ensure common cut-offs for high concentrations and risk assessment. Randomized cardiovascular outcome trials are needed to provide final evidence of causality and to assess the potential clinical benefit of novel, potent lipoprotein(a) lowering therapies.

Lack of Association of LPA Gene Polymorphisms with Coronary Artery Disease in Pakistani Subjects

Coronary artery disease (CAD) is the leading cause of death worldwide. Pakistan faces a high epidemic of CAD, and the disease burden is increasing with the passage of time. Several genetic markers have been reported to be significantly associated with CAD; one of them is the lipoprotein A gene. The aim of the current investigation was to genotype the LPA gene SNPs, rs3798220 and rs10455872, in Pakistani subjects with CAD in a case control study design. The genotyping was done by TaqMan allelic discrimination assay. The results showed that the cases had significantly higher prevalence of diabetes (64.6%), hypertension (62.1%), and smoking habits (29.5%). The level of cholesterol in cases was higher than in controls (208.25 ± 54.11 vs. 175.34 ± 43.51, p ≤ 0.0001). The LDL-C was higher in cases than in controls (104.62 ± 37.94 vs. 77.05 ± 21.17, p ≤ 0.0001). Similarly, triglycerides were also higher in cases than in controls (214.51 ± 74.60 vs. 190.54 ± 70.26, p ≤ 0.0001), whereas HDL-C was lower in cases than in controls (45.13 ± 11.63 vs. 67.9 ± 17.57, p ≤ 0.0001). For rs3798220, the risk allele (C) frequency was 0.005 in cases and 0.002 in controls. For rs10455872, the risk allele (G) frequency was 0.017 in cases and 0.014 in controls. The risk allele frequencies were not significantly different between cases and controls (p > 0.05). In conclusion, these two LPA SNPs do not contribute significantly to CAD progression and cannot be used as independent risk factors for CAD in Pakistani population.

Lp(a) (Lipoprotein[a]) Concentrations and Incident Atherosclerotic Cardiovascular Disease: New Insights From a Large National Biobank

OBJECTIVE

Lp(a) (lipoprotein[a]) concentrations are associated with atherosclerotic cardiovascular disease (ASCVD), and new therapies that enable potent and specific reduction are in development. In the largest study conducted to date, we address 3 areas of uncertainty: (1) the magnitude and shape of ASCVD risk conferred across the distribution of lipoprotein(a) concentrations; (2) variation of risk across racial and clinical subgroups; (3) clinical importance of a high lipoprotein(a) threshold to guide therapy. Approach and Results: Relationship of lipoprotein(a) to incident ASCVD was studied in 460 506 middle-aged UK Biobank participants. Over a median follow-up of 11.2 years, incident ASCVD occurred in 22 401 (4.9%) participants. Median lipoprotein(a) concentration was 19.6 nmol/L (25th-75th percentile 7.6-74.8). The relationship between lipoprotein(a) and ASCVD appeared linear across the distribution, with a hazard ratio of 1.11 (95% CI, 1.10-1.12) per 50 nmol/L increment. Substantial differences in concentrations were noted according to race-median values for white, South Asian, black, and Chinese individuals were 19, 31, 75, and 16 nmol/L, respectively. However, risk per 50 nmol/L appeared similar-hazard ratios of 1.11, 1.10, and 1.07 for white, South Asian, and black individuals, respectively. A high lipoprotein(a) concentration defined as ≥150 nmol/L was present in 12.2% of those without and 20.3% of those with preexisting ASCVD and associated with hazard ratios of 1.50 (95% CI, 1.44-1.56) and 1.16 (95% CI, 1.05-1.27), respectively.

CONCLUSIONS

Lipoprotein(a) concentrations predict incident ASCVD among middle-aged adults within primary and secondary prevention contexts, with a linear risk gradient across the distribution. Concentrations are variable across racial subgroups, but the associated risk appears similar.

Diet and Lp(a): Does Dietary Change Modify Residual Cardiovascular Risk Conferred by Lp(a)?

Lipoprotein(a) [Lp(a)] is an independent, causal, genetically determined risk factor for cardiovascular disease (CVD). We provide an overview of current knowledge on Lp(a) and CVD risk, and the effect of pharmacological agents on Lp(a). Since evidence is accumulating that diet modulates Lp(a), the focus of this paper is on the effect of dietary intervention on Lp(a). We identified seven trials with 15 comparisons of the effect of saturated fat (SFA) replacement on Lp(a). While replacement of SFA with carbohydrate, monounsaturated fat (MUFA), or polyunsaturated fat (PUFA) consistently lowered low-density lipoprotein cholesterol (LDL-C), heterogeneity in the Lp(a) response was observed. In two trials, Lp(a) increased with carbohydrate replacement; one trial showed no effect and another showed Lp(a) lowering. MUFA replacement increased Lp(a) in three trials; three trials showed no effect and one showed lowering. PUFA or PUFA + MUFA inconsistently affected Lp(a) in four trials. Seven trials of diets with differing macronutrient compositions showed similar divergence in the effect on LDL-C and Lp(a). The identified clinical trials show diet modestly affects Lp(a) and often in the opposing direction to LDL-C. Further research is needed to understand how diet affects Lp(a) and its properties, and the lack of concordance between diet-induced LDL-C and Lp(a) changes.

Relationship Between Low-Density Lipoprotein Cholesterol and Lipoprotein(a) Lowering in Response to PCSK9 Inhibition With Evolocumab

Background

Beyond their potent LDL (low‐density lipoprotein) cholesterol (LDL‐C)–lowering efficacy (50–60%), PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitors also reduce Lp(a) (lipoprotein[a]) levels by 25% to 30%, suggesting a 2:1 response ratio. We aimed to characterize the relationship between LDL‐C and Lp(a) lowering by evolocumab, a PCSK9 inhibitor, in a large clinical trial population and to determine the prevalence of concordant/discordant LDL‐C and Lp(a) responses to PCSK9 inhibition.

Methods and Results

Data were analyzed from 4 randomized, 12‐week, multicenter, phase 3 evolocumab trials. Patients with familial hypercholesterolemia, nonfamilial hypercholesterolemia, or statin intolerance participated in the trials. The main measure was the degree of concordance or discordance of LDL‐C and Lp(a) in response to PCSK9 inhibition; concordant response was defined as LDL‐C reduction >35% and Lp(a) reduction >10%. The study cohort comprised 895 patients (438 female; median age: 59.0 years [interquartile range: 51–66 years]). Baseline mean level of LDL‐C was 133.6 mg/dL (SE: 1.7) and median Lp(a) level was 46.4 mg/dL (interquartile range: 18.4–82.4 mg/dL). A discordant response was observed in 165 (19.7%) patients. With these cutoffs, the prevalence of discordance was higher when considering baseline Lp(a) concentrations >30 mg/dL (26.5%) or >50 mg/dL (28.6%).

Conclusions

We demonstrate high prevalence of discordance in LDL‐C and Lp(a) reduction in response to evolocumab, particularly when considering higher baseline Lp(a) concentrations, indicating the possibility of alternative pathways beyond LDLR (LDL receptor)–mediated clearance involved in Lp(a) reduction by evolocumab.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01763827, NCT01763866, NCT01763905, NCT01763918.

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Investigation of LPA sequence variants rs6415084, rs3798220 with conventional coronary artery disease in Iranian CAD patients

BACKGROUND

Conventional coronary artery disease (CAD) is the leading cause of morbidity and mortality in the general population. In recent years, multiple CAD promising risk factors have been reported and used for risk stratification. Lipoprotein(a) [LPA] concentration in plasma was shown associated with CAD risk and LPA genetic variants in different ethnic groups remains less clear.

METHODS

We obtained data from 100 affected patients with established CAD and 100 healthy controls. We tested Body mass index (BMI), total cholesterol level (TC), systolic blood pressure (SBP), diastolic blood pressure (DBP), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), fasting blood sugar (FBS) and two LPA (rs10455872 and rs3798220 SNPs) between cases and healthy controls. TaqMan SNP genotyping assays were performed to detect variants.

RESULTS

Obtained data for BMI, TC, SBP, DBP, and LDL have significantly difference between two groups. Individually, the single SNPs were not associated with CAD in different analysis models. Also there was no significant difference in the incidence of CAD among cases carrying different genotypes of the two variants in LPA with p> 0.05.

DISCUSSION

In this study patients with CAD, lipoprotein(a) concentrations and genetic variants showed no associations and we conclude that these variables are not useful risk factors to predict progression to disease is Iranian population. However, the prevalence and association of LPA SNPs with size of LPA and isoforms are highly variable and genetic background-specific.

CONCLUSION

Our data did not indicate a relationship between genomic LPA variants (rs10455872 and rs3798220) and subsequent cardiovascular events in Iranian CAD patients. We did not confirm the association of the theses SNPs with CAD in our samples of Iranian patients. For the studied variants, our finding is consistent with reports which showed the lack of this genetic association in other populations.

There is an association between a genetic polymorphism in the ZNF259 gene involved in lipid metabolism and coronary artery disease

BACKGROUND

Recent genome-wide association studies (GWAS) have identified several genetic variants that influence the risk of dyslipidemia and coronary artery disease (CAD). In this study, we have examined the potential association of five SNPs variants related to lipid pathway, previously identified in GWAS studies (ZNF259 C>G, CETP I405VA/G, LPA C>T, LPLS447X and PSRC1 A>G) with CAD.

METHODS

Two hundred and ninety subjects including 194 patients with coronary artery disease and 96 controls were enrolled, followed by the analyses of anthropometric/biochemical parameters. Genotyping was carried out using Taq-Man real-time PCR based method. The association of the genetic polymorphisms with CAD was determined using univariate and multivariate analyses.

RESULTS

CAD patients had a higher (p < 0.05) fasting blood glucose (FBG), total cholesterol (TC), high sensitivity C-reactive protein (hs-CRP), low-density lipoprotein cholesterol (LDL-C) and waist circumference. Results showed that subjects with CETP rs5882 genetic variant, AA&AG genotypes, had a higher risk of developing Coronary artery disease [OR: 2.1, 95% CI (1.2-4.1), p value = 0.015]. Also subjects who carried the G allele of the ZNF259 polymorphism were at an increased the risk of developing CAD [OR 1.86, 95% CI: 1.06-3.25, p value = 0.029] and had an increased TC, LDL and TG levels (p < 0.05). Furthermore, no statistically significant association was found between genetic polymorphisms of PSRC1 A>G, LPL S447X and LPA C>T and CAD.

CONCLUSION

We identified a relationship between a genetic variant in CETP and ZNF259 gene with CAD and CAD and lipid profile, respectively. Further investigation in a larger population may help to investigate the value of emerging marker as a risk stratification marker in CAD and its risk factors.

South Asian Cardiovascular Disease & Cancer Risk: Genetics & Pathophysiology

South Asians (SAs) are at heightened risk for cardiovascular disease as compared to other ethnic groups, facing premature and more severe coronary artery disease, and decreased insulin sensitivity. This disease burden can only be partially explained by conventional risk factors, suggesting the need for a specific cardiovascular risk profile for SAs. Current research, as explored through a comprehensive literature review, suggests the existence of population specific genetic risk factors such as lipoprotein(a), as well as population specific gene modulating factors. This review catalogues the available research on cardiovascular disease and genetics, anthropometry, and pathophysiology, and cancer genetics among SAs, with a geographical focus on the U.S. A tailored risk profile will hinge upon population customized classification and treatment guidelines, informed by continued research.

PCSK9 and Atherosclerosis - Lipids and Beyond

Even though it is only a little over a decade from the discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9) as a plasma protein that associates with both high and low cholesterol syndromes, a rich body of knowledge has developed, and drugs inhibiting this target have been approved in many markets. While the majority of research in recent years has focused on the impact of therapeutic antagonism of this molecule, important lines of investigation have emerged characterizing its unique physiology as it relates to cholesterol metabolism and atherosclerosis. The PCSK9 story is unfolding rapidly but is far from complete. One chapter that is of particular interest is the possible direct link between PCSK9 and atherosclerosis. This review specifically examines this relationship drawing from data produced from experimental models of plaque biology and inflammation, atherosclerosis imaging studies, and observational epidemiology.

Serum lipoprotein(a) level as long-term predictor of cardiovascular mortality in a large sample of subjects in primary cardiovascular prevention: data from the Brisighella Heart Study

BACKGROUND

High lipoprotein(a) [Lp(a)] levels have been re-evaluated as an independent risk factor for atherosclerotic vascular diseases.

METHODS

We assessed whether serum Lp(a) levels can significantly influence long-term survival in subjects with an equal general cardiovascular (CV) risk profile. We prospectively evaluated a sample of 1215 adult subjects from the Brisighella Heart Study cohort (M: 608; F: 607; aged 40-69) who had no cardiovascular disease at enrolment. According to the CUORE project risk-charts (Italian-specific risk-charts), individuals were stratified into a low-(n=865), an intermediate-(n=275) and a high-(n=75) cardiovascular risk groups. Kaplan-Meier 25-year survival analysis was carried out examining apart each class of risk and the log-rank statistic was used to estimate, when statistically possible, the survival time of the subjects stratified into quartiles of Lp(a).

RESULTS

Subjects at high and intermediate CV risk aged 56-69years (regardless of gender) and women aged 40-55years with a low CV risk profile who had lower Lp(a) levels showed a significant benefit on CV mortality (P<0.05 always) and, indicatively, on the estimated survival time (even P<0.05). The ROC curves constructing for each CV risk group using Lp(a) as test-variable and death as state-variable identified serum Lp(a) as an independent long-term CV mortality prognosticator for subjects at high CV risk (AUC=0.63, 95%CI [0.50-0.76], P=0.049) and women with an intermediate CV risk profile (AUC=0.7, 95%CI [0.52-0.79], P=0.034).

CONCLUSIONS

In the light of our finding and at the best of the previous knowledge, dosing Lp(a) is confirmed as important in subjects at high or medium risk (even if in primary prevention for CV diseases), especially in women.

Human Genetics and the Causal Role of Lipoprotein(a) for Various Diseases

Lipoprotein(a) [Lp(a)] is a highly atherogenic lipoprotein that is under strong genetic control by the LPA gene locus. Genetic variants including a highly polymorphic copy number variation of the so called kringle IV repeats at this locus have a pronounced influence on Lp(a) concentrations. High concentrations of Lp(a) as well as genetic variants which are associated with high Lp(a) concentrations are both associated with cardiovascular disease which very strongly supports causality between Lp(a) concetrations and cardiovascular disease. This method of using a genetic variant that has a pronounced influence on a biomarker to support causality with an outcome is called Mendelian randomization approach and was applied for the first time two decades ago with data from Lp(a) and cardiovascular disease. This approach was also used to demonstrate a causal association between high Lp(a) concentrations and aortic valve stenosis, between low concentrations and type-2 diabetes mellitus and to exclude a causal association between Lp(a) concentrations and venous thrombosis. Considering the high frequency of these genetic variants in the population makes Lp(a) the strongest genetic risk factor for cardiovascular disease identified so far. Promising drugs that lower Lp(a) are on the horizon but their efficacy in terms of reducing clinical outcomes still has to be shown.

LPA Gene, Ethnicity, and Cardiovascular Events

BACKGROUND

The relationship of LPA single nucleotide polymorphisms (SNPs), apolipoprotein(a) isoforms, and lipoprotein(a) [Lp(a)] levels with major adverse cardiovascular events (MACE) in different ethnic groups is not well known.

METHODS

LPA SNPs, apolipoprotein(a) isoforms, Lp(a), and oxidized phospholipids on apolipoprotein B-100 (OxPL-apoB) levels were measured in 1792 black, 1030 white, and 597 Hispanic subjects enrolled in the Dallas Heart Study. Their interdependent relationships and prospective association with MACE after median 9.5-year follow-up were determined.

RESULTS

LPA SNP rs3798220 was most prevalent in Hispanics (42.38%), rs10455872 in whites (14.27%), and rs9457951 in blacks (32.92%). The correlation of each of these SNPs with the major apolipoprotein(a) isoform size was highly variable and in different directions among ethnic groups. In the entire cohort, Cox regression analysis with multivariable adjustment revealed that quartiles 4 of Lp(a) and OxPL-apoB were associated with hazard ratios (95% confidence interval) for time to MACE of 2.35 (1.50-3.69, P<0.001) and 1.89 (1.26-2.84, P=0.003), respectively, versus quartile 1. Addition of the major apolipoprotein(a) isoform and the 3 LPA SNPs to these models attenuated the risk, but significance was maintained for both Lp(a) and OxPL-apoB. Evaluating time to MACE in specific ethnic groups, Lp(a) was a positive predictor and the size of the major apolipoprotein(a) isoform was an inverse predictor in blacks, the size of the major apolipoprotein(a) isoform was an inverse predictor in whites, and OxPL-apoB was a positive predictor in Hispanics.

CONCLUSIONS

The prevalence and association of LPA SNPs with size of apolipoprotein(a) isoforms, Lp(a), and OxPL-apoB levels are highly variable and ethnicity-specific. The relationship to MACE is best explained by elevated plasma Lp(a) or OxPL-apoB levels, despite significant ethnic differences in LPA genetic markers.

Effect of Two Lipoprotein (a)-Associated Genetic Variants on Plasminogen Levels and Fibrinolysis

Two genetic variants (rs3798220 and rs10455872) in the apolipoprotein (a) gene (LPA) have been implicated in cardiovascular disease (CVD), presumably through their association with lipoprotein (a) [Lp(a)] levels. While Lp(a) is recognized as a lipoprotein with atherogenic and thrombogenic characteristics, it is unclear whether or not the two Lp(a)-associated genetic variants are also associated with markers of thrombosis (i.e., plasminogen levels and fibrinolysis). In the present study, we genotyped the two genetic variants in 2919 subjects of the Old Order Amish (OOA) and recruited 146 subjects according to the carrier and noncarrier status for rs3798220 and rs10455872, and also matched for gender and age. We measured plasma Lp(a) and plasminogen levels in these subjects, and found that the concentrations of plasma Lp(a) were 2.62- and 1.73-fold higher in minor allele carriers of rs3798220 and rs10455872, respectively, compared with noncarriers (P = 2.04 × 10⁻¹⁷ and P = 1.64 × 10⁻⁶, respectively). By contrast, there was no difference in plasminogen concentrations between carriers and noncarriers of rs3798220 and rs10455872. Furthermore, we observed no association between carrier status of rs3798220 or rs10455872 with clot lysis time. Finally, plasminogen mRNA expression in liver samples derived from 76 Caucasian subjects was not significantly different between carriers and noncarriers of these two genetic variants. Our results provide further insight into the mechanism of action behind two genetic variants previously implicated in CVD risk and show that these polymorphisms are not major modulating factors for plasma plasminogen levels and fibrinolysis.

From Lipids to Inflammation: New Approaches to Reducing Atherosclerotic Risk

The introduction of statins ≈ 30 years ago ushered in the era of lipid lowering as the most effective way to reduce risk of atherosclerotic cardiovascular disease. Nonetheless, residual risk remains high, and statin intolerance is frequently encountered in clinical practice. After a long dry period, the field of therapeutics targeted to lipids and atherosclerosis has entered a renaissance. Moreover, the demonstration of clinical benefits from the addition of ezetimibe to statin therapy in subjects with acute coronary syndromes has renewed the enthusiasm for the cholesterol hypothesis and the hope that additional agents that lower low-density lipoprotein will decrease risk of atherosclerotic cardiovascular disease. Drugs in the orphan disease category are now available for patients with the most extreme hypercholesterolemia. Furthermore, discovery and rapid translation of a novel biological pathway has given rise to a new class of cholesterol-lowering drugs, the proprotein convertase subtilisin kexin-9 inhibitors. Trials of niacin added to statin have failed to demonstrate cardiac benefits, and 3 cholesterol ester transfer protein inhibitors have also failed to reduce atherosclerotic cardiovascular disease risk, despite producing substantial increases in HDL levels. Although the utility of triglyceride-lowering therapies remains uncertain, 2 large clinical trials are testing the influence of omega-3 polyunsaturated fatty acids on atherosclerotic events in hypertriglyceridemia. Novel antisense therapies targeting apolipoprotein C-III (for triglyceride reduction) and apo(a) (for lipoprotein(a) reduction) are showing a promising trajectory. Finally, 2 large clinical trials are formally putting the inflammatory hypothesis of atherosclerosis to the test and may open a new avenue for cardiovascular disease risk reduction.

Structure, function, and genetics of lipoprotein (a)

Lipoprotein (a) [Lp(a)] has attracted the interest of researchers and physicians due to its intriguing properties, including an intragenic multiallelic copy number variation in the LPA gene and the strong association with coronary heart disease (CHD). This review summarizes present knowledge of the structure, function, and genetics of Lp(a) with emphasis on the molecular and population genetics of the Lp(a)/LPA trait, as well as aspects of genetic epidemiology. It highlights the role of genetics in establishing Lp(a) as a risk factor for CHD, but also discusses uncertainties, controversies, and lack of knowledge on several aspects of the genetic Lp(a) trait, not least its function.

Lipoprotein(a): novel target and emergence of novel therapies to lower cardiovascular disease risk

PURPOSE OF REVIEW

This article summarizes recent observations on the role of lipoprotein(a) [Lp(a)] as a risk factor mediating cardiovascular disease.

RECENT FINDINGS

Lp(a) is a highly prevalent cardiovascular risk factor, with levels above 30 mg/dl affecting 20-30% of the global population. Up until now, no specific therapies have been developed to lower Lp(a) levels. Three major levels of evidence support the notion that elevated Lp(a) levels are a causal, independent, genetic risk factor for cardiovascular disease: epidemiologic studies and meta-analyses, genome-wide association studies and Mendelian randomization studies. Recent studies also have noted that individuals with low levels of Lp(a) are associated with a higher risk of incident type 2 diabetes mellitus, and conversely individuals with high levels have a lower risk, but this association does not appear to be causal. Novel therapies to lower Lp(a) include PCSK9 inhibitors and antisense oligonucleotides directly preventing translation of apolipoprotein(a) mRNA.

SUMMARY

With this robust and expanding clinical database, a reawakening of interest in Lp(a) as clinical risk factor is taking place. Trials are underway with novel drugs that substantially lower Lp(a) and may reduce its contribution to cardiovascular disease.

Targeting lipoprotein (a): an evolving therapeutic landscape

Robust epidemiologic and genetic studies have solidified the role of lipoprotein (a) [Lp(a)] as an independent and causal risk factor for cardiovascular disease. The increased cardiovascular risk of Lp(a) is mediated through both proatherogenic and prothrombotic/antifibrinolytic mechanisms. Several societies recommend Lp(a) screening for patients with high cardiovascular risk, although no consensus exists on the management of patients with elevated Lp(a). However, numerous pharmacologic approaches are being evaluated that have the potential to reduce Lp(a) and will be the focus of this review. The majority of these interventions have been developed for other lipid-lowering indications, but also lower Lp(a). There are also novel therapies in development that specifically target Lp(a). The efficacy of these therapies varies, and their role in the evolving lipoprotein therapeutic landscape has yet to be determined. Nevertheless, targeted Lp(a) reduction is certainly intriguing and will likely continue to be an active area of investigation in the future.

Mipomersen, an antisense oligonucleotide to apolipoprotein B-100, reduces lipoprotein(a) in various populations with hypercholesterolemia: results of 4 phase III trials

OBJECTIVE

Lp(a) is an independent, causal, genetic risk factor for cardiovascular disease and aortic stenosis. Current pharmacological lipid-lowering therapies do not optimally lower Lp(a), particularly in patients with familial hypercholesterolemia (FH).

APPROACH AND RESULTS

In 4 phase III trials, 382 patients on maximally tolerated lipid-lowering therapy were randomized 2:1 to weekly subcutaneous mipomersen 200 mg (n=256) or placebo (n=126) for 26 weeks. Populations included homozygous FH, heterozygous FH with concomitant coronary artery disease (CAD), severe hypercholesterolemia, and hypercholesterolemia at high risk for CAD. Lp(a) was measured 8× between baseline and week 28 inclusive. Of the 382 patients, 57% and 44% had baseline Lp(a) levels >30 and >50 mg/dL, respectively. In the pooled analysis, the mean percent decrease (median, interquartile range in Lp(a) at 28 weeks was significantly greater in the mipomersen group compared with placebo (-26.4 [-42.8, -5.4] versus -0.0 [-10.7, 15.3]; P<0.001). In the mipomersen group in patients with Lp(a) levels >30 or >50 mg/dL, attainment of Lp(a) values ≤30 or ≤50 mg/dL was most frequent in homozygous FH and severe hypercholesterolemia patients. In the combined groups, modest correlations were present between percent change in apolipoprotein B-100 and Lp(a) (r=0.43; P<0.001) and low-density lipoprotein cholesterol and Lp(a) (r=0.36; P<0.001) plasma levels.

CONCLUSIONS

Mipomersen consistently and effectively reduced Lp(a) levels in patients with a variety of lipid abnormalities and cardiovascular risk. Modest correlations were present between apolipoprotein B-100 and Lp(a) lowering but the mechanistic relevance mediating Lp(a) reduction is currently unknown.

[Clinical significance of and treatment options for increased lipoprotein(a)]

Lipoprotein(a) has been shown to be associated with an increased incidence of cardiovascular diseases for decades. However, only recent research revealed more about its physiological function and its role in the development of cardiovascular diseases. The authors summarize the physiological role of lipoprotein(a), causes and treatment of elevated lipoprotein(a) level, and the association between lipoprotein(a) and cardiovascular diseases.

LPA rs10455872 polymorphism is associated with coronary lesions in Brazilian patients submitted to coronary angiography

BACKGROUND

Polymorphisms in the LPA gene were associated with coronary artery disease (CAD). However, there are differences in the allelic frequencies, Lp(a) levels, and significant association with CAD according to ethnic groups. In this scenario, the main aim of this study was to assess the influence of the LPA polymorphisms on coronary lesions in Brazilian patients.

METHODS

1,394 consecutive patients submitted to coronary angiography to study suggestive CAD and twenty coronary segments were scored. Genotyping for the LPA rs10455872 and rs3798220 polymorphisms were performed by high resolution melting analysis.

RESULTS

The frequencies of the rs10455872 G and rs3798220 C variant alleles were 6.4% and 6.2%, respectively. LPA rs10455872 G variant allele was associated with higher odds ratio of having coronary lesions in an adjusted model (OR = 2.02, 95% CI = 1.10-3.72, p = 0.02). Scores of coronary lesions (extension, severity, and Gensini scores) were significantly different among rs10455872 genotype groups. Coronary lesions was not associated with LPA rs3798220 (OR = 1.09, 95% CI = 0.67-1.76, p = 0.73) and scores of coronary lesions were not different among rs3798220 genotypes.

CONCLUSIONS

We confirmed the association of the LPA rs10455872 with CAD in a large sample of Brazilian patients. For the LPA rs3798220, our finding is consistent with studies which showed the lack of this genetic association.

Relook at lipoprotein (A): independent risk factor of coronary artery disease in north Indian population

AIMS

Lipoprotein (a) [Lp(a)] levels have shown wide ethnic variations. Sparse data on mean Lp(a) levels, its link with clinical variables and severity of coronary artery disease (CAD) in North Indian population needed further studies.

METHODS

150 patients, each of single vessel disease (SVD), double vessel disease (DVD) and triple vessel disease (TVD) with 150 healthy controls were drawn for the study. Serum Lp(a) estimation was performed by immunoturbidimetric method.

RESULTS

Lp(a) had a skewed distribution. Median Lp(a) level was significantly raised in cases as compared to controls (median 30.30 vs. 20 mg/dl, p < 0.001). Cases with acute coronary syndrome (ACS, 55.8%) had significantly higher median Lp(a) levels as compared to those with chronic stable angina (35.4 mg/dl vs. 23 mg/dl, p < 0.001). Significant difference in median Lp(a) levels were observed in patients with DVD or TVD versus control (30, 39.05 vs 20 mg/dl, p < 0.008). Lp(a) level was found to be an independent risk factor for CAD (AOR{adjusted odds ratio} 1.018, 95% CI 1.010-1.027; p < 0.001). Analysis using Lp(a) as categorical variable showed that progressive increase in Lp(a) concentration was associated with increased risk of CAD [AOR from lowest to highest quartile (1, 1.04, 1.43 and 2.65, p value for trend = 0.00026)]. Multivariably AOR of CAD for subjects with Lp(a) in the highest quartile (above 40 mg/dl) compared to those with Lp(a) ≤40 mg/dl was 2.308 (95% CI 1.465-3.636, p < 0.001).

CONCLUSION

Lp(a) above 40 mg/dl (corresponding to 75th percentile)assessed by an isoform insensitive assay is an independent risk factor for CAD. Raised Lp(a) level is also associated with increased risk of ACS and multivessel CAD.

Update on lipoprotein(a) as a cardiovascular risk factor and mediator

Recent genetic studies have put the spotlight back onto lipoprotein(a) [Lp(a)] as a causal risk factor for coronary heart disease. However, there remain significant gaps in our knowledge with respect to how the Lp(a) particle is assembled, the route of its catabolism, and the mechanism(s) of Lp(a) pathogenicity. It has long been speculated that the effects of Lp(a) in the vasculature can be attributed to both its low-density lipoprotein moiety and the unique apolipoprotein(a) component, which is strikingly similar to the kringle-containing fibrinolytic zymogen plasminogen. However, the ability of Lp(a) to modulate either purely thrombotic or purely atherothrombotic processes in vivo remains unclear. The presence of oxidized phospholipid on Lp(a) may underlie many of the proatherosclerotic effects of Lp(a) that have been identified both in cell models and in animal models, and provides a possible avenue for identifying therapeutics aimed at mitigating the effects of Lp(a) in the vasculature. However, the beneficial effects of targeted Lp(a) therapeutics, designed to either lower Lp(a) concentrations or interfere with its effects, on cardiovascular outcomes remains to be determined.

Genetics of lipid traits and relationship to coronary artery disease

Despite the critical importance of plasma lipoproteins in the development of atherosclerosis, varying degrees of evidence surround the causal associations of lipoproteins with coronary artery disease (CAD). These causal contributions can be assessed by employing genetic variants as unbiased proxies for lipid levels. A relatively large number of low-density lipoprotein cholesterol (LDL-C) variants strongly associate with CAD, confirming the causal impact of this lipoprotein on atherosclerosis. Although not as firmly established, genetic evidence supporting a causal role of triglycerides (TG) in CAD is growing. Conversely, high-density lipoprotein cholesterol (HDL-C) variants not associated with LDL-C or TG have not yet been shown to be convincingly associated with CAD, raising questions about the causality of HDL-C in atherosclerosis. Finally, genetic variants at the LPA locus associated with lipoprotein(a) [Lp(a)] are decisively linked to CAD, indicating a causal role for Lp(a). Translational investigation of CAD-associated lipid variants may identify novel regulatory pathways with therapeutic potential to alter CAD risk.

Genetic variants associated with myocardial infarction and the risk factors in Chinese population

BACKGROUND

Recent genome-wide association (GWA) studies in Caucasians identified multiple single nucleotide polymorphisms (SNPs) associated with coronary artery disease (CAD). The associations of those SNPs with myocardial infarction (MI) have not been replicated in Asian populations. Among those previously identified SNPs, we selected nine (rs10953541, rs1122608, rs12190287, rs12413409, rs1412444, rs1746048, rs3798220, rs4977574, rs579459, in or near genes 7q22, LDLR, TCF21, CYP17A1, LIPA, CXCL12, LPA, CDKN2A, ABO, respectively) because of the relatively high minor allele frequencies in Chinese individuals and tested the associations of the SNPs with MI and MI related risk factors in Chinese population.

METHODS AND RESULTS

We conducted a case-control association study on a cohort of 2365 MI patients and 2678 unrelated controls from the Chinese population. Genotyping of 9 SNPs were performed by the TaqMan Real Time PCR method. After age, sex, and BMI adjustment, we observed the SNPs rs12190287, rs12413409, rs1412444, rs1746048 and rs4977574, were significantly associated with MI in additive models and rs12190287, rs12413409, rs4977574 were significantly associated with phenotypes of MI at the same time. We also found three SNPs rs1122608, rs3798220 and rs579459 were significantly associated with risk factors of MI, although they had no association with MI in Chinese population.

CONCLUSION

Results of this study indicate that 5 SNPs were associated with MI and 3 SNPs were associated with associated with lipoprotein levels but not with MI in a Chinese population. The present study supports some CAD-related genes in Caucasian as important genes for MI in a Chinese population.

Lipoprotein (a), LPA Ile4399Met, and fibrin clot properties

INTRODUCTION

Elevated lipoprotein(a) (Lp(a)) levels were reported to be associated with dense fibrin clots. The apo(a) component of Lp(a) is encoded by LPA, and the Met allele of the LPA Ile4399Met polymorphism is associated with elevated Lp(a) levels and cardiovascular disease risk. We investigated whether Ile4399Met was associated with fibrin clot properties.

MATERIALS AND METHODS

We determined plasma Lp(a) levels, fibrin clot permeability and lysis time for 64 LPA 4399Met carriers and 128 noncarriers matched for age, sex, ethnicity, and enrollment site.

RESULTS

Elevated Lp(a) levels were associated with reduced clot permeability and prolonged lysis time (P<0.0001). Carriers of 4399Met had higher Lp(a) levels compared with noncarriers (P=0.0003). However, this association differed by ethnicity (P=0.003 for interaction between genotype and ethnicity): compared with noncarriers, 4399Met carriers had 2.89 fold higher Lp(a) levels among Caucasians while no difference was observed among non-Caucasians (primarily East Asians and Hispanics). Among all subjects, no association was observed between Ile4399Met and clot properties, but this relationship also differed by ethnicity: among non-Caucasians, 4399Met carriers had increased clot permeability and shorter lysis time; whereas among Caucasians, the trend was for decreased permeability and longer lysis time (P<0.01 for interactions between genotype and ethnicity).

CONCLUSIONS

We confirmed that elevated Lp(a) levels are associated with dense fibrin clots, and found that the association of LPA 4399Met carriers and clot permeability as well as lysis time differ by ethnicity.

The pharmacogenomics of statins

The statin class of cholesterol-lowering drugs have been used for decades to successfully lower plasma cholesterol concentrations and cardiovascular risk. Adverse effects of statins are generally considered mild, but increase with age of patients and polypharmacy. One aspect of statin therapy that is still difficult for prescribers to predict is the individual's response to statin therapy. Recent advances in the field of pharmacogenomics have indicated variants of candidate genes that affect statin efficacy and safety. In this review, a number of candidates that affect statin pharmacokinetics and pharmacodynamics are discussed. Some of these candidates, in particular those involved in import and efflux of statins, have now been linked to increased risk of side effects. Furthermore, pharmacogenomic studies continue to reveal new players that are involved in the fine-tuning of the complex regulation of cholesterol homeostasis and response to statins.

Lipoprotein(a), cardiovascular disease, and contemporary management

Elevated lipoprotein(a) (Lp[a]) is a causal genetic risk factor for cardiovascular disease. To determine if current evidence supports both screening and treatment for elevated Lp(a) in high-risk patients, an English-language search of PubMed and MEDLINE was conducted. In population studies, there is a continuous association between Lp(a) concentrations and cardiovascular risk, with synergistic effects when low-density lipoprotein (LDL) is also elevated. Candidates for Lp(a) screening include patients with a personal or family history of premature cardiovascular disease, familial hypercholesterolemia, recurrent cardiovascular events, or inadequate LDL cholesterol (LDL-C) responses to statins. Given the comparative strength of clinical evidence, reducing LDL-C to the lowest attainable value with a high-potency statin should be the primary focus of lipid-modifying therapies. If the Lp(a) level is 30 mg/dL or higher in a patient who has the aforementioned characteristics plus residual LDL-C elevations (≥70-100 mg/dL) despite maximum-potency statins or combination statin therapy, the clinician may consider adding niacin (up to 2 g/d). If, after these interventions, the patient has progressive coronary heart disease (CHD) or LDL-C levels of 160-200 mg/dL or higher, LDL apheresis should be contemplated. Although Lp(a) is a major causal risk factor for CHD, no currently available controlled studies have suggested that lowering it through either pharmacotherapy or LDL apheresis specifically and significantly reduces coronary risk. Further research is needed to (1) optimize management in order to reduce CHD risk associated with elevated Lp(a) and (2) determine what other intermediate- or high-risk groups might benefit from Lp(a) screening.

Lipoprotein(a): a promising marker for residual cardiovascular risk assessment

Atherosclerotic cardiovascular diseases (CVD) are still the leading cause of morbidity and mortality worldwide, although optimal medical therapy has been prescribed for primary and secondary preventions. Residual cardiovascular risk for some population groups is still considerably high although target low density lipoprotein-cholesterol (LDL-C) level has been achieved. During the past few decades, compelling pieces of evidence from clinical trials and meta-analyses consistently illustrate that lipoprotein(a) (Lp(a)) is a significant risk factor for atherosclerosis and CVD due to its proatherogenic and prothrombotic features. However, the lack of effective medication for Lp(a) reduction significantly hampers randomized, prospective, and controlled trials conducting. Based on previous findings, for patients with LDL-C in normal range, Lp(a) may be a useful marker for identifying and evaluating the residual cardiovascular risk, and aggressively lowering LDL-C level than current guidelines' recommendation may be reasonable for patients with particularly high Lp(a) level.

Determinants of binding of oxidized phospholipids on apolipoprotein (a) and lipoprotein (a)

Oxidized phospholipids (OxPLs) are present on apolipoprotein (a) [apo(a)] and lipoprotein (a) [Lp(a)] but the determinants influencing their binding are not known. The presence of OxPLs on apo(a)/Lp(a) was evaluated in plasma from healthy humans, apes, monkeys, apo(a)/Lp(a) transgenic mice, lysine binding site (LBS) mutant apo(a)/Lp(a) mice with Asp(55/57)→Ala(55/57) substitution of kringle (K)IV10)], and a variety of recombinant apo(a) [r-apo(a)] constructs. Using antibody E06, which binds the phosphocholine (PC) headgroup of OxPLs, Western and ELISA formats revealed that OxPLs were only present in apo(a) with an intact KIV10 LBS. Lipid extracts of purified human Lp(a) contained both E06- and nonE06-detectable OxPLs by tandem liquid chromatography-mass spectrometry (LC-MS/MS). Trypsin digestion of 17K r-apo(a) showed PC-containing OxPLs covalently bound to apo(a) fragments by LC-MS/MS that could be saponified by ammonium hydroxide. Interestingly, PC-containing OxPLs were also present in 17K r-apo(a) with Asp(57)→Ala(57) substitution in KIV10 that lacked E06 immunoreactivity. In conclusion, E06- and nonE06-detectable OxPLs are present in the lipid phase of Lp(a) and covalently bound to apo(a). E06 immunoreactivity, reflecting pro-inflammatory OxPLs accessible to the immune system, is strongly influenced by KIV10 LBS and is unique to human apo(a), which may explain Lp(a)'s pro-atherogenic potential.

When should we measure lipoprotein (a)?

Recently published epidemiological and genetic studies strongly suggest a causal relationship of elevated concentrations of lipoprotein (a) [Lp(a)] with cardiovascular disease (CVD), independent of low-density lipoproteins (LDLs), reduced high density lipoproteins (HDL), and other traditional CVD risk factors. The atherogenicity of Lp(a) at a molecular and cellular level is caused by interference with the fibrinolytic system, the affinity to secretory phospholipase A2, the interaction with extracellular matrix glycoproteins, and the binding to scavenger receptors on macrophages. Lipoprotein (a) plasma concentrations correlate significantly with the synthetic rate of apo(a) and recent studies demonstrate that apo(a) expression is inhibited by ligands for farnesoid X receptor. Numerous gaps in our knowledge on Lp(a) function, biosynthesis, and the site of catabolism still exist. Nevertheless, new classes of therapeutic agents that have a significant Lp(a)-lowering effect such as apoB antisense oligonucleotides, microsomal triglyceride transfer protein inhibitors, cholesterol ester transfer protein inhibitors, and PCSK-9 inhibitors are currently in trials. Consensus reports of scientific societies are still prudent in recommending the measurement of Lp(a) routinely for assessing CVD risk. This is mainly caused by the lack of definite intervention studies demonstrating that lowering Lp(a) reduces hard CVD endpoints, a lack of effective medications for lowering Lp(a), the highly variable Lp(a) concentrations among different ethnic groups and the challenges associated with Lp(a) measurement. Here, we present our view on when to measure Lp(a) and how to deal with elevated Lp(a) levels in moderate and high-risk individuals.

Atherogenic changes in low-density lipoprotein particle profiles were not observed in non-obese women with polycystic ovary syndrome

STUDY QUESTION

Is a preponderance of small dense low-density lipoprotein-cholesterol (LDL-C) observed in non-obese women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Non-obese Korean women with PCOS have no quantitative or qualitative changes in LDL-C profiles.

WHAT IS KNOWN ALREADY

Small dense LDL particles (sd-LDL) are more atherogenic than large buoyant ones and are strongly associated with coronary artery disease independent of other risk factors. Many investigators have found an increased proportion of atherogenic sd-LDL or a decreased mean LDL particle size in women with PCOS, but all of these studies have been based primarily on obese or overweight women with PCOS.

STUDY DESIGN, SIZE, DURATION

This was a case-control study evaluating complete lipid and lipoprotein profiles in 64 PCOS patients and 64 age- and BMI-matched controls. All women with PCOS in our study population were not obese. To determine the differences in the LDL particle profiles between PCOS phenotypes, the patients with PCOS were divided into two subgroups according to the presence of clinical or biochemical hyperandrogenism.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using the Rotterdam criteria, we recruited 64 women (18-40 years) with PCOS who were attending a tertiary university hospital. A total of 64 premenopausal control women were matched with patients based on exact age and BMI (± 1.0 kg/m(2)). All the participants fell within the non-obese range of the BMI (<25 kg/m(2)) according to the definition of obesity for Asians. The LDL subfraction was analyzed by 3% polyacrylamide gel tube electrophoresis. Seven LDL subclasses were quantified and LDL subclasses 3-7 were small LDL subfractions. LDL subfraction scores were calculated based on the following weighted scoring system developed by the manufacturer: scores of <5.5 were categorized as phenotype A (large, buoyant LDLs), and those >5.5 were categorized as non-A phenotype (sd-LDLs). The system also determined the mean LDL particle size diameter.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no differences in the absolute level of LDL-C, mean LDL diameter or percentage of atherogenic sd-LDLs between PCOS patients and controls or between hyperandrogenic and non-hyperandrogenic PCOS subgroups. Also, none of the subjects showed a non-A LDL phenotype. The most notable finding of our study was the difference in the lipoprotein (a) levels and prevalence of its elevation in PCOS patients versus controls (P = 0.002 and P = 0.004, respectively), and between PCOS subgroups (P = 0.030 and P = 0.047, respectively).

LIMITATIONS, REASONS FOR CAUTION

Inclusion of only non-obese subjects, small sample size and lack of information on other potential confounding factors, such as differences in diet and/or exercise patterns.

WIDER IMPLICATIONS OF THE FINDINGS

Although our findings suggest that non-obese women with PCOS have no significant quantitative or qualitative changes in LDL-C profile, data on obese Korean women with PCOS could offer complementary findings about the possible relationship between the magnitude of obesity and LDL phenotype. Further investigations are needed to determine whether a change in lipoprotein (a) in non-obese women with PCOS is also found in other ethnic groups.

STUDY FUNDING/COMPETING INTEREST(S)

No conflict of interest exists. This study was supported by a grant of the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A100624).

TRIAL REGISTRATION NUMBER

N/A.

Lipoprotein(a): resurrected by genetics

Plasma lipoprotein(a) [Lp(a)] is a quantitative genetic trait with a very broad and skewed distribution, which is largely controlled by genetic variants at the LPA locus on chromosome 6q27. Based on genetic evidence provided by studies conducted over the last two decades, Lp(a) is currently considered to be the strongest genetic risk factor for coronary heart disease (CHD). The copy number variation of kringle IV in the LPA gene has been strongly associated with both Lp(a) levels in plasma and risk of CHD, thereby fulfilling the main criterion for causality in a Mendelian randomization approach. Alleles with a low kringle IV copy number that together have a population frequency of 25-35% are associated with a doubling of the relative risk for outcomes, which is exceptional in the field of complex genetic phenotypes. The recently identified binding of oxidized phospholipids to Lp(a) is considered as one of the possible mechanisms that may explain the pathogenicity of Lp(a). Drugs that have been shown to lower Lp(a) have pleiotropic effects on other CHD risk factors, and an improvement of cardiovascular endpoints is up to now lacking. However, it has been established in a proof of principle study that lowering of very high Lp(a) by apheresis in high-risk patients with already maximally reduced low-density lipoprotein cholesterol levels can dramatically reduce major coronary events.

Lipoprotein(a) and risk of coronary, cerebrovascular, and peripheral artery disease: the EPIC-Norfolk prospective population study

OBJECTIVE

Although the association between circulating levels of lipoprotein(a) [Lp(a)] and risk of coronary artery disease (CAD) and stroke is well established, its role in risk of peripheral arterial disease (PAD) remains unclear. Here, we examine the association between Lp(a) levels and PAD in a large prospective cohort. To contextualize these findings, we also examined the association between Lp(a) levels and risk of stroke and CAD and studied the role of low-density lipoprotein as an effect modifier of Lp(a)-associated cardiovascular risk.

METHODS AND RESULTS

Lp(a) levels were measured in apparently healthy participants in the European Prospective Investigation of Cancer (EPIC)-Norfolk cohort. Cox regression was used to quantify the association between Lp(a) levels and risk of PAD, stroke, and CAD outcomes. During 212 981 person-years at risk, a total of 2365 CAD, 284 ischemic stroke, and 596 PAD events occurred in 18 720 participants. Lp(a) was associated with PAD and CAD outcomes but not with ischemic stroke (hazard ratio per 2.7-fold increase in Lp(a) of 1.37, 95% CI 1.25-1.50, 1.13, 95% CI 1.04-1.22 and 0.91, 95% CI 0.79-1.03, respectively). Low-density lipoprotein cholesterol levels did not modify these associations.

CONCLUSIONS

Lp(a) levels were associated with future PAD and CAD events. The association between Lp(a) and cardiovascular disease was not modified by low-density lipoprotein cholesterol levels.

Emerging therapeutic agents to lower lipoprotein (a) levels

PURPOSE OF REVIEW

Recent epidemiological and genetic studies have suggested that lipoprotein (a) [Lp(a)] is a causal mediator of cardiovascular disease (CVD). There is now interest in evaluating Lp(a) as a therapeutic target. This review will summarize emerging therapeutic agents to lower Lp(a).

RECENT FINDINGS

Apheresis is the most efficacious method to lower Lp(a). Currently, there are no approved drugs to specifically lower Lp(a). However, recent data has demonstrated that Lp(a) can be significantly lowered, along with reductions in other apolipoprotein B-100 (apoB) containing lipoproteins, with antisense oligonucleotides to apoB, monoclonal antibodies to proprotein convertase subtilisin/kexin type 9, cholesterol ester transfer protein inhibitors, and thyromimetics. The farnesoid X receptor/fibroblast growth factor axis and interleukin-6 also influence Lp(a) levels and may be targets of therapy. Finally, specific apolipoprotein (a) [apo(a)] inhibitors apo(a) have been developed and reduce apo(a) mRNA and protein levels up to 86% without significantly affecting other lipoproteins.

SUMMARY

Lp(a) remains the last major lipoprotein disorder without any specific therapy. With the strong and accumulating data on its role as a causal risk factor for CVD, a rationale exists to develop novel agents to reduce Lp(a) and test the hypothesis that this will lead to reduced CVD events.

Lipoprotein(a) and cardiovascular disease in diabetic patients

Lipoprotein(a) (Lp[a]) is a LDL-like particle consisting of an ApoA moiety linked to one molecule of ApoB(100). Recent data from large-scale prospective studies and genetic association studies provide highly suggestive evidence for a potentially causal role of Lp(a) in affecting risk of cardiovascular disease (CVD) in general populations. Patients with Type 2 diabetes display clustered metabolic abnormalities and elevated risk of CVD. Lower plasma Lp(a) levels were observed in diabetic patients in several recent studies. Epidemiology studies of Lp(a) and CVD risk in diabetic patients generated inconsistent results. We recently found that Lp(a)-related genetic markers did not predict CVD in two diabetic cohorts. The current data suggest that Lp(a) may differentially affect cardiovascular risk in diabetic patients and in the general population. More prospective studies, Mendelian randomization analysis and functional studies are needed to clarify the causal relationship of Lp(a) and CVD in diabetic patients.