Genetic Determinants of Myocardial Infarction Risk in Familial Hypercholesterolemia

Sex differences in treatment of familial hypercholesterolaemia: a meta-analysis

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) is a highly prevalent monogenic disorder characterized by elevated LDL cholesterol (LDL-C) levels and premature atherosclerotic cardiovascular disease. Sex disparities in diagnosis, lipid-lowering therapy, and achieved lipid levels have emerged worldwide, resulting in barriers to care in FH. A systematic review was performed to investigate sex-related disparities in treatment, response, and lipid target achievement in FH (PROSPERO, CRD42022353297).

METHODS

MEDLINE, Embase, The Cochrane library, PubMed, Scopus, PsycInfo, and grey literature databases were searched from inception to 26 April 2023. Records were eligible if they described sex differences in the treatment of adults with FH.

RESULTS

Of 4432 publications reviewed, 133 met our eligibility criteria. In 16 interventional clinical trials (eight randomized and eight non-randomized; 1840 participants, 49.4% females), there were no differences between males and females in response to fixed doses of lipid-lowering therapy, suggesting that sex was not a determinant of response. Meta-analysis of 25 real-world observational studies (129 441 participants, 53.4% females) found that females were less likely to be on lipid-lowering therapy compared with males (odds ratio .74, 95% confidence interval .66-.85). Importantly, females were less likely to reach an LDL-C < 2.5 mmol/L (odds ratio .85, 95% confidence interval .74-.97). Similarly, treated LDL-C levels were higher in females. Despite this, male sex was associated with a two-fold greater relative risk of major adverse cardiovascular events including myocardial infarction, atherosclerotic cardiovascular disease, and cardiovascular mortality.

CONCLUSIONS

Females with FH were less likely to be treated intensively and to reach guideline-recommended LDL-C targets. This sex bias represents a surmountable barrier to clinical care.

Role of non-coding variants in cardiovascular disease

Cardiovascular diseases (CVDs) constitute one of the significant causes of death worldwide. Different pathological states are linked to CVDs, which despite interventions and treatments, still have poor prognoses. The genetic component, as a beneficial tool in the risk stratification of CVD development, plays a role in the pathogenesis of this group of diseases. The emergence of genome-wide association studies (GWAS) have led to the identification of non-coding parts associated with cardiovascular traits and disorders. Variants located in functional non-coding regions, including promoters/enhancers, introns, miRNAs and 5'/3' UTRs, account for 90% of all identified single-nucleotide polymorphisms associated with CVDs. Here, for the first time, we conducted a comprehensive review on the reported non-coding variants for different CVDs, including hypercholesterolemia, cardiomyopathies, congenital heart diseases, thoracic aortic aneurysms/dissections and coronary artery diseases. Additionally, we present the most commonly reported genes involved in each CVD. In total, 1469 non-coding variants constitute most reports on familial hypercholesterolemia, hypertrophic cardiomyopathy and dilated cardiomyopathy. The application and identification of non-coding variants are beneficial for the genetic diagnosis and better therapeutic management of CVDs.

Familial Hypercholesterolaemia as a Predisposing Factor for Atherosclerosis

Lipid metabolism alterations are an important component of the pathogenesis of atherosclerosis. However, it is now clear that the atherogenesis process involves more than one mechanism, and more than one condition can predispose this condition. Multiple risk factors contribute to the atherosclerosis initiation and define its course. Familial hypercholesterolaemia is a disorder of lipid metabolism that often leads to atherosclerosis development. As is clear from the disease name, the hallmark is the increased levels of low-density lipoprotein cholesterol (LDL-C) in blood. This creates favourable conditions for atherogenesis. In this review, we briefly described the familial hypercholesterolaemia and summarized data on the relationship between familial hypercholesterolaemia and atherosclerosis.

Prevalence of genetically defined familial hypercholesterolemia and the impact on acute myocardial infarction in Taiwanese population: A hospital-based study

Background

Familial hypercholesterolemia (FH) is a common genetic disorder with markedly increased risk of coronary artery diseases (CAD), especially acute myocardial infarction (AMI). However, genetic tests for FH are not always necessary in the current diagnostic criteria of FH, which might lead to underestimation of the prevalence of FH and a lack of awareness of FH-associated CAD and AMI. We aimed to explore the prevalence of genetically defined FH in the hospital-based population and to determine the impact of FH risk variants on CAD and AMI.

Methods

The study participants were recruited between June 24, 2019 and May 12, 2021, at a medical center in Taiwan, in cooperation with the Taiwan Precision Medicine Initiative (TPMI) project. The prevalence of FH was calculated and the effects of FH pathogenic variants on CAD and AMI were analyzed by logistic regression models and shown as ORs and 95% CI.

Results

The prevalence of genetically defined FH was 1.13% in the hospital-based population in Taiwan. Highest LDL and total cholesterol levels were observed in patients with LDLR rs28942084 (LDL 219.4±55.2; total cholesterol 295.8±55.4). There was an approximately 4-fold increased risk of hyperlipidemia in subjects with the LDLR rs769446356 polymorphism (OR, 4.42; 95% CI, 1.92-10.19) and AMI in individuals with the LDLR rs730882109 polymorphism (OR, 3.79; 95% CI, 2.26-6.35), and a 2-fold increased risk of CAD in those with the LDLR rs749038326 polymorphism (OR, 2.14; 95% CI, 1.31-3.50), compared with the groups without pathogenic variants of FH.

Conclusions

The prevalence of genetically defined FH was 1.13% in the hospital-based population in Taiwan, which was higher than the rate observed in individuals with clinically defined FH. The risk of CAD and AMI was increased to varying degrees in subjects with different FH risk alleles. Close monitoring and risk stratification strategy are essential in high-risk patients with FH risk alleles to facilitate early detection and treatments.

Monogenic Versus Polygenic Forms of Hypercholesterolemia and Cardiovascular Risk: Are There Any Differences?

PURPOSE OF REVIEW

Common DNA variants with small effects work together to create susceptibility to polygenic hypercholesterolemia. Some clinicians wonder whether patients with polygenic hypercholesterolemia have less severe clinical features compared to patients with monogenic familial hypercholesterolemia (FH) caused by rare deleterious variants.

RECENT FINDINGS

Studies performed in cohorts of patients with both monogenic and polygenic hypercholesterolemia have assessed lipid levels, non-invasive markers of atherosclerosis, and clinical end points, including major adverse cardiovascular events. The totality of data suggests a gradient across genotypes. Specifically, individuals with polygenic hypercholesterolemia have deleterious phenotypes that are intermediate in severity between those in patients with monogenic hypercholesterolemia and in control subjects. Although clinical variables in patients with polygenic hypercholesterolemia are less severe than in those with monogenic hypercholesterolemia, cardiovascular risk is still very high in these patients compared to controls. Patients with polygenic hypercholesterolemia must be treated assertively.

Finding inhibitors for PCSK9 using computational methods

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the key targets for atherosclerosis drug development as its binding with low-density lipoprotein receptor leads to atherosclerosis. The protein-ligand interaction helps to understand the actual mechanism for the pharmacological action. This research aims to discover the best inhibitory candidates targeting PCSK9. To start with, reported ACE inhibitors were incorporated into pharmacophore designing using PharmaGist to produce pharmacophore models. Selected models were later screened against the ZINC database using ZINCPHARMER to define potential drug candidates that were docked with the target protein to understand their interactions. Molecular docking revealed the top 10 drug candidates against PCSK9, with binding energies ranging from -9.8 kcal·mol^-1 to -8.2 kcal·mol^-1, which were analyzed for their pharmacokinetic properties and oral bioavailability. Some compounds were identified as plant-derived compounds like (S)-canadine, hesperetin or labetalol (an antihypertensive drug). Molecular dynamics results showed that these substances formed stable protein-ligand complexes. (S)-canadine-PCSK9 complex was the most stable with the lowest RMSD. It was concluded that (S)-canadine may act as a potential inhibitor against atherosclerosis for the development of new PCSK9 inhibitory drugs in future in vitro research.

The brave new world of genetic testing in the management of the dyslipidaemias

PURPOSE OF REVIEW

With the exception of familial hypercholesterolaemia, the value of genetic testing for managing dyslipidaemias is not established. We review the genetics of major dyslipidaemias in context of clinical practice.

RECENT FINDINGS

Genetic testing for familial hypercholesterolaemia is valuable to enhance diagnostic precision, cascade testing, risk prediction and the use of new medications. Hypertriglyceridaemia may be caused by rare recessive monogenic, or by polygenic, gene variants; genetic testing may be useful in the former, for which antisense therapy targeting apoC-III has been approved. Familial high-density lipoprotein deficiency is caused by specific genetic mutations, but there is no effective therapy. Familial combined hyperlipidaemia (FCHL) is caused by polygenic variants for which there is no specific gene testing panel. Familial dysbetalipoproteinaemia is less frequent and commonly caused by APOE ε2ε2 homozygosity; as with FCHL, it is responsive to lifestyle modifications and statins or/and fibrates. Elevated lipoprotein(a) is a quantitative genetic trait whose value in risk prediction over-rides genetic testing; treatment relies on RNA therapeutics.

SUMMARY

Genetic testing is not at present commonly available for managing dyslipidaemias. Rapidly advancing technology may presage wider use, but its worth will require demonstration of cost-effectiveness and a healthcare workforce trained in genomic medicine.