Genetics of familial hypercholesterolemia

Investigation of the genetic background of familial hypercholesterolemia in a Turkish cohort and its clinical implications

OBJECTIVE

Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated plasma cholesterol and an increased risk of early-onset coronary artery disease (CAD). FH has a complex genetic basis. Advances in molecular genetic techniques have deepened our understanding of FH, which is critical for accurate classification, CAD risk assessment, and optimized treatment strategies. This study aimed to evaluate the monogenic etiologies of FH and polygenic background as a possible cause of clinical FH phenotype and their relationship to clinical outcomes in a Turkish cohort.

METHODS

Patients were selected based on the Simon Broome Criteria. Various molecular techniques were employed, including Sanger sequencing, multiplex-ligation dependent probe amplification (MLPA), next-generation sequencing (NGS) panel analysis, and RNA-based studies. For the first time in a Turkish FH cohort, we calculated 6-single nucleotide polymorphism (SNP) and 12-SNP scores and compared them with a control group.

RESULTS

Multiple variants were identified, including 2 novel variants and a synonymous splice region variant in LDLR, which was shown to disrupt splicing through RNA analysis. The 6-SNP and 12-SNP scores displayed patterns consistent with other populations.

CONCLUSION

Our findings suggest subtle differences in the monogenic etiology of FH in the Turkish population, with variant negative patients predominantly exhibiting polygenic background. Additionally, polygenic factors appear to influence the phenotype even in variant-positive individuals.

Case report of familial hypercholesterolemia with internal carotid neck swelling

Familial hypercholesterolemia is a multi-gene disorder affecting 1 in 200-500 individual which is characterized by increased level of total cholesterol and low density lipoprotein (LDL) which deposit cholesterol reach protein leading to xanthomas, corneal arcus and prone to develop risk for atherosclerosis and coronary heart disease. 11 year female, born of consanguineous marriage attended with yellowish patches (Xanthelasma) bilaterally present over upper eyelid, buttock since 5-6 years. In family history younger girl along with both parents has Xanthelasma. In investigations, routine blood, urine and ECG& ECHO was normal except lipid profile of patient and sibling was abnormal. Child was treated with atorvastatin and dietary advice. In follow up after 3 month, child had complained of neck pain and swelling to left side. Then USG neck and Color Doppler showed reduced diastolic flow of left ICA and type two plaques and type 111 plaque in Rt common carotid artery. Anti-platelets was added and referred to cardiologist for coronary angiography which showed LAD - proximal mid distal diffuse plaque, LCX- proximal eccentric plaque. This case highlights the significance of conscious and proactive genetic screening for familial hypercholesterolemia especially in consanguineous marriage, to diagnose, treat and prevent mortality with premature coronary artery disease.

Hypercholesterolemia and inflammation-Cooperative cardiovascular risk factors

BACKGROUND

Maintaining low concentrations of plasma low-density lipoprotein cholesterol (LDLc) over time decreases the number of LDL particles trapped within the artery wall, slows the progression of atherosclerosis and delays the age at which mature atherosclerotic plaques develop. This substantially reduces the lifetime risk of atherosclerotic cardiovascular disease (ASCVD) events. In this context, plaque development and vulnerability result not only from lipid accumulation but also from inflammation.

RESULTS

Changes in the composition of immune cells, including macrophages, dendritic cells, T cells, B cells, mast cells and neutrophils, along with altered cytokine and chemokine release, disrupt the equilibrium between inflammation and anti-inflammatory mechanisms at plaque sites. Considering that it is not a competition between LDLc and inflammation, but instead that they are partners in crime, the present narrative review aims to give an overview of the main inflammatory molecular pathways linked to raised LDLc concentrations and to describe the impact of lipid-lowering approaches on the inflammatory and lipid burden. Although remarkable changes in LDLc are driven by the most recent lipid lowering combinations, the relative reduction in plasma C-reactive protein appears to be independent of the magnitude of LDLc lowering.

CONCLUSION

Identifying clinical biomarkers of inflammation (e.g. interleukin-6) and possible targets for therapy holds promise for monitoring and reducing the ASCVD burden in suitable patients.

Improved Genetic Characterization of Hypercholesterolemia in Latvian Patients with Familial Hypercholesterolemia: A Combined Monogenic and Polygenic Approach Using Whole-Genome Sequencing

Despite the implementation of next-generation sequencing-based genetic testing on patients with clinical familial hypercholesterolemia (FH), most cases lack complete genetic characterization. We aim to investigate the utility of the polygenic risk score (PRS) in specifying the genetic background of patients from the Latvian Registry of FH (LRFH). We analyzed the whole-genome sequencing (WGS) data of the clinically diagnosed FH patients (n = 339) and controls selected from the Latvian reference population (n = 515). Variant pathogenicity in FH patients was classified according to the ACMG/AMP guidelines. The low-density lipoprotein cholesterol (LDL-C) and lipoprotein (a) (LPA) PRS were calculated based on the WGS data. We identified unique causative variants in 80 (23.6%) of the tested individuals (39 variants in FH genes and 4 variants in phenocopy genes, with 6 variants being novel). The LDL-C PRS was highly discriminative compared to the LPA PRS. Nevertheless, both PRS were able to explain the genetic cause of hypercholesterolemia in 26.3% of the remaining non-monogenic patients. The combined genetic analysis of monogenic and polygenic hypercholesterolemia resulted in 43.7% genetically explained hypercholesterolemia cases. Even though the application of PRS alone does not exclude monogenic testing in clinical FH patients, it is a valuable tool for diagnosis specification.

Causal relationships of familial hypercholesterolemia with the risk of multiple vitamin deficiencies: a Mendelian randomization study

Background

The causal relationship between familial hypercholesterolemia (FH) and various vitamin deficiencies has not yet been elucidated. Therefore, this study investigated the cause-and-effect relationship between FH and the risk of multiple vitamin deficiencies in humans.

Methods

Mendelian randomization (MR) analysis was performed by extracting six datasets for FH, FH with ischemic heart disease (IHD), and vitamin deficiency (vitamin A, thiamine, other B-group vitamins, and vitamin D) from the FinnGen study, covering a total of 329,115; 316,290; 354,932; 354,949; 355,411 and 355,238 individuals, respectively.

Results

FH was suggestively associated with higher odds of thiamine deficiency [inverse variance weighted odds ratio (ORIVW) 95% confidence interval (CI): 1.62 (1.03, 2.55), P = 0.036] and vitamin D deficiencies [ORIVW CI: 1.35 (1.04, 1.75), P = 0.024], low-density lipoprotein receptor (LDLR) rs112898275 variant, rs11591147 and rs499883 in proprotein convertase subtilisin/kexin 9 (PCSK9), rs9644862 in cyclin-dependent kinase inhibitor 2 B antisense RNA1 (CDKN2B-AS1), and rs142834163 in dedicator of cytokinesis 6 (DOCK6) and rs115478735 in ABO blood group (ABO) strongly influenced the risk of thiamine deficiency, while the rs7412 variant in apolipoprotein E (APOE) mostly influenced the risk of vitamin D deficiency. FH with IHD was suggestively associated with higher odds of vitamin D deficiency (ORIVW, weighted median [WM][95%CI]: 1.31 [1.05, 1.64]; 1.47 [1.10, 1.97]) (P = 0.018; 0.010) without any single significant SNPs observed.

Conclusion

FH was positively associated with increased risks of thiamine and vitamin D deficiencies, revealing a prospective and unfortunate complication of FH.

Highlights of Cardiovascular Disease Prevention Studies Presented at the 2023 American Heart Association Scientific Sessions

PURPOSE OF REVIEW

Focused review highlighting ten select studies presented at the 2023 American Heart Association (AHA) Scientific Sessions.

RECENT FINDINGS

Included studies assessed semaglutide and cardiovascular outcomes in overweight or obese patients without diabetes (SELECT); dapagliflozin in patients with acute myocardial infarction without diabetes (DAPA-MI); effects of dietary sodium on systolic blood pressure in middle-aged individuals (CARDIA-SSBP); long-term blood pressure control after hypertensive pregnancy with physician guided self-management (POP-HT); effect and safety of zilebesiran, an RNA interference therapy, for sustained blood pressure reduction (KARDIA-1); recaticimab add-on therapy in patients with non-familial hypercholesterolemia and mixed hyperlipidemia (REMAIN-2); efficacy and safety of lepodisiran an extended duration short-interfering RNA targeting lipoprotein(a); safety and pharmacodynamic effects of an investigational DNA base editing medicine that inactivates the PCSK9 gene and lowers LDL cholesterol (VERVE-101); automated referral to centralized pharmacy services for evidence-based statin initiation in high-risk patients; and effects of intensive blood pressure lowering in reducing risk of cardiovascular events (ESPRIT). Research presented at the 2023 AHA Scientific Sessions emphasized innovative strategies in cardiovascular disease prevention and management.

Unveiling Familial Hypercholesterolemia-Review, Cardiovascular Complications, Lipid-Lowering Treatment and Its Efficacy

Familial hypercholesterolemia (FH) is a genetic disorder primarily transmitted in an autosomal-dominant manner. We distinguish two main forms of FH, which differ in the severity of the disease, namely homozygous familial hypercholesterolemia (HoFH) and heterozygous familial hypercholesterolemia (HeFH). The characteristic feature of this disease is a high concentration of low-density lipoprotein cholesterol (LDL-C) in the blood. However, the level may significantly vary between the two mentioned types of FH, and it is decidedly higher in HoFH. A chronically elevated concentration of LDL-C in the plasma leads to the occurrence of certain abnormalities, such as xanthomas in the tendons and skin, as well as corneal arcus. Nevertheless, a significantly more severe phenomenon is leading to the premature onset of cardiovascular disease (CVD) and its clinical implications, such as cardiac events, stroke or vascular dementia, even at a relatively young age. Due to the danger posed by this medical condition, we have investigated how both non-pharmacological and selected pharmacological treatment impact the course of FH, thereby reducing or postponing the risk of clinical manifestations of CVD. The primary objective of this review is to provide a comprehensive summary of the current understanding of FH, the effectiveness of lipid-lowering therapy in FH and to explain the anatomopathological correlation between FH and premature CVD development, with its complications.

Hypercholesterolemia induced by spontaneous oligogenic mutations in rhesus macaques (Macaca mulatta)

BACKGROUND

A rhesus macaque with the fourth highest plasma cholesterol (CH) levels of 501 breeding macaques was identified 22 years ago. Seven offspring with gene mutations causing hypercholesterolemia were obtained.

METHODS

Activity of low-density lipoprotein receptor (LDLR), plasma CH levels and mRNA expression levels of LDLR were measured after administration of 0.1% (0.27 mg/kcal) or 0.3% CH.

RESULTS

Activity of p. (Cys82Tyr) of LDLR was 71% and 42% in the heterozygotes and a homozygote, respectively. The mRNA expression level of LDLR in the p. (Val241Ile) of membrane-bound transcription factor protease, site 2 (MBTPS2, S2P protein) was 0.83 times lower than normal levels. LDLR mRNA levels were increased for up to 4 weeks by administration of 0.3% CH before suddenly decreasing to 80% of the baseline levels after 6 weeks.

CONCLUSION

Oligogenic mutations of p. (Cys82Tyr) in LDLR and p. (Val241Ile) in MBTPS2 (S2P) caused hypercholesterolemia exceeding cardiovascular risk levels under a 0.1% CH diet.

Genetic and molecular architecture of familial hypercholesterolemia

Atherosclerotic cardiovascular disease is the leading cause of death globally. Despite its important risk of premature atherosclerosis and cardiovascular disease, familial hypercholesterolemia (FH) is still largely underdiagnosed worldwide. It is one of the most frequently inherited diseases due to mutations, for autosomal dominant forms, in either of the LDLR, APOB, and PCSK9 genes or possibly a few mutations in the APOE gene and, for the rare autosomal forms, in the LDLRAP1 gene. The discovery of the genes implicated in the disease has largely helped to improve the diagnosis and treatment of FH from the LDLR by Brown and Goldstein, as well as the introduction of statins, to PCSK9 discovery in FH by Abifadel et al., and the very rapid availability of PCSK9 inhibitors. In the last two decades, major progress has been made in clinical and genetic diagnostic tools and the therapeutic arsenal against FH. Improving prevention, diagnosis, and treatment and making them more accessible to all patients will help reduce the lifelong burden of the disease.

Monoclonal Antibodies, Gene Silencing and Gene Editing (CRISPR) Therapies for the Treatment of Hyperlipidemia-The Future Is Here

Hyperlipidemia is a significant risk factor for atherosclerotic cardiovascular disease. Undertreatment of elevated lipids persists despite existing therapies. Here, we provide an update on monoclonal antibodies, gene silencing therapies, and gene editing techniques for the management of hyperlipidemia. The current era of cutting-edge pharmaceuticals targeting low density lipoprotein cholesterol, PCSK9, lipoprotein (a), angiopoietin-like 3, and apolipoprotein C3 are reviewed. We outline what is known, studies in progress, and futuristic goals. This review of available and upcoming biotechnological lipid therapies is presented for clinicians managing patients with familial hyperlipidemia, statin intolerance, hypertriglyceridemia, or elevated lipoprotein (a) levels.

Generalidades del metabolismo de los lípidos y del manejo de la de los lípidos y del manejo de la hipercolesterolemia

Introducción: los lípidos hacen parte fundamental de la biología humana y son precursores de la síntesis de hormonas esteroideas y derivados eicosanoides. Los requerimientos de lípidos son satisfechos a través de la vía endógena que consiste en la formación de lípidos a nivel celular y la exógena la cual se da con la ingesta y absorción de grasas provenientes de la dieta. El conocimiento de estas vías es importante ya que es el punto de partida para un abordaje terapéutico adecuado y oportuno, pero a pesar de la facilidad de las metodologías de laboratorio para su cuantificación y diagnóstico, la hipercolesterolemia familiar sigue siendo subdiagnosticada. Discusión: para los clínicos es importante pues es una de las causas de eventos cardiovasculares prematuros. La presentación heterocigota tiene una prevalencia aproximada de 1/500 personas. En su mayoría son secundarias a la incapacidad en la actividad de los receptores LDL para el procesamiento del colesterol. Este compromiso de receptores está dado por múltiples mutaciones. Conclusión: las manifestaciones clínicas están relacionadas con niveles de LDL elevados (mayores de 190 mg/dL) y colesterol total mayor de 300 mg/dL presentes desde el nacimiento. Las estatinas son la primera línea de tratamiento, pero pueden resultar insuficientes requiriendo tratamientos adicionales con ezetimiba, secuestradores de ácidos biliares e inhibidores de la PCSK9.

Site-specific genome editing in treatment of inherited diseases: possibility, progress, and perspectives

Advancements in genome editing enable permanent changes of DNA sequences in a site-specific manner, providing promising approaches for treating human genetic disorders caused by gene mutations. Recently, genome editing has been applied and achieved significant progress in treating inherited genetic disorders that remain incurable by conventional therapy. Here, we present a review of various programmable genome editing systems with their principles, advantages, and limitations. We introduce their recent applications for treating inherited diseases in the clinic, including sickle cell disease (SCD), β-thalassemia, Leber congenital amaurosis (LCA), heterozygous familial hypercholesterolemia (HeFH), etc. We also discuss the paradigm of ex vivo and in vivo editing and highlight the promise of somatic editing and the challenge of germline editing. Finally, we propose future directions in delivery, cutting, and repairing to improve the scope of clinical applications.

Machine Learning Methods for Hypercholesterolemia Long-Term Risk Prediction

Cholesterol is a waxy substance found in blood lipids. Its role in the human body is helpful in the process of producing new cells as long as it is at a healthy level. When cholesterol exceeds the permissible limits, it works the opposite, causing serious heart health problems. When a person has high cholesterol (hypercholesterolemia), the blood vessels are blocked by fats, and thus, circulation through the arteries becomes difficult. The heart does not receive the oxygen it needs, and the risk of heart attack increases. Nowadays, machine learning (ML) has gained special interest from physicians, medical centers and healthcare providers due to its key capabilities in health-related issues, such as risk prediction, prognosis, treatment and management of various conditions. In this article, a supervised ML methodology is outlined whose main objective is to create risk prediction tools with high efficiency for hypercholesterolemia occurrence. Specifically, a data understanding analysis is conducted to explore the features association and importance to hypercholesterolemia. These factors are utilized to train and test several ML models to find the most efficient for our purpose. For the evaluation of the ML models, precision, recall, accuracy, F-measure, and AUC metrics have been taken into consideration. The derived results highlighted Soft Voting with Rotation and Random Forest trees as base models, which achieved better performance in comparison to the other models with an AUC of 94.5%, precision of 92%, recall of 91.8%, F-measure of 91.7% and an accuracy equal to 91.75%.

Lumping versus splitting: How to approach defining a disease to enable accurate genomic curation

The dilemma of how to categorize and classify diseases has been debated for centuries. The field of medical genetics has historically approached nosology based on clinical phenotypes observed in patients and families. Advances in genomic sequencing and understanding of genetic contributions to disease often provoke a need to reassess these classifications. The Clinical Genome Resource (ClinGen) has developed frameworks to classify the strength of evidence underlying monogenic gene-disease relationships, variant pathogenicity, and clinical actionability. It is therefore necessary to define the disease entity being evaluated, which can be challenging for genes associated with multiple conditions and/or a broad phenotypic spectrum. We therefore developed criteria to guide "lumping and splitting" decisions and improve consistency in defining monogenic gene-disease relationships. Here, we outline the precuration process, the lumping and splitting guidelines with examples, and describe the implications for clinical diagnosis, informatics, and care management.

Individualized Treatment for Patients With Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is one of the most common and, therefore, important inherited disorders in preventive cardiology. This disease is mainly caused by a single pathogenic mutation in the low-density lipoprotein receptor or its associated genes. Moreover, it is correlated with a high risk of cardiovascular disease. However, the phenotype severity even in this monogenic disease significantly varies. Thus, the current study aimed to describe FH and its importance and the factors (inherited and acquired) contributing to differences in phenotype severity. Different lipid-modification therapies according to these factors can lead to individualized treatments, which are also essential in the general populations.

Remediation of ABCG5-Linked Macrothrombocytopenia With Ezetimibe Therapy

To investigate refractory hypercholesterolemia, a female patient and relatives were subjected to whole-genome sequencing. The proband was found to have compound heterozygous substitutions p. Arg446Gln and c.1118+3G>T in ABCG5, one of two genes causing sitosterolemia. When tracing these variants in the full pedigree, all maternally related heterozygotes for the intronic ABCG5 variant exhibited large platelets (over 30 fl), which segregated in an autosomal dominant manner, consistent with macrothrombocytopenia, or large platelet syndrome which may be associated with a bleeding tendency. In vitro cell-line and in vivo rat model experiments supported a pathogenic role for the variant and the macrothrombocytopenia was recapitulated in heterozygous rats and human cell lines exhibiting that single variant. Ezetimibe treatment successfully ameliorated all the symptoms of the proband with sitosterolemia and resolved the macrothrombocytopenia of the treated heterozygote relatives. Subsequently, in follow up these observations, platelet size, and size distribution were measured in 1,180 individuals; 30 were found to be clinically abnormal, three of which carried a single known pathogenic ABCG5 variant (p.Arg446Ter) and two individuals carried novel ABCG5 variants of uncertain significance. In this study, we discovered that identification of large platelets and therefore a possible macrothrombocytopenia diagnosis could easily be inadvertently missed in clinical practice due to variable instrument settings. These findings suggest that ABCG5 heterozygosity may cause macrothrombocytopenia, that Ezetimibe treatment may resolve macrothrombocytopenia in such individuals, and that increased attention to platelet size on complete blood counts can aid in the identification of candidates for ABCG5 genetic testing who might benefit from Ezetimibe treatment.

Beneficial effects of PCSK9 inhibition with alirocumab in familial hypercholesterolemia involve modulation of new immune players

Familial hypercholesterolemia (FH) is associated with low-grade systemic inflammation, a key driver of premature atherosclerosis. We investigated the effects of inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) function on inflammatory state, endothelial dysfunction and cardiovascular outcomes in patients with FH. Fourteen patients with FH were evaluated before and 8 weeks after administration of a PCSK9 blocking monoclonal antibody (alirocumab, 150 mg/subcutaneous/14 days). In vivo and ex vivo analysis revealed that alirocumab blunted the attachment of leukocytes to TNFα-stimulated human umbilical arterial endothelial cells (HUAEC) and suppressed the activation of platelets and most leukocyte subsets, which was accompanied by the diminished expression of CX₃CR1, CXCR6 and CCR2 on several leukocyte subpopulations. By contrast, T-regulatory cell activation was enhanced by alirocumab treatment, which also elevated anti-inflammatory IL-10 plasma levels and lowered circulating pro-inflammatory cytokines. Plasma levels of IFNγ positively correlated with levels of total and LDL-cholesterol, whereas circulating IL-10 levels negatively correlated with these key lipid parameters. In vitro analysis revealed that TNFα stimulation of HUAEC increased the expression of PCSK9, whereas endothelial PCSK9 silencing reduced TNFα-induced mononuclear cell adhesion mediated by Nox5 up-regulation and p38-MAPK/NFκB activation, concomitant with reduced SREBP2 expression. PCSK9 silencing also decreased endothelial CX₃CL1 and CXCL16 expression and chemokine generation. In conclusion, PCSK9 inhibition impairs systemic inflammation and endothelial dysfunction by constraining leukocyte-endothelium interactions. PCSK9 blockade may constitute a new therapeutic approach to control the inflammatory state associated with FH, preventing further cardiovascular events in this cardiometabolic disorder.

Analysis of Rare Variants in Genes Related to Lipid Metabolism in Patients with Familial Hypercholesterolemia in Western Siberia (Russia)

The aim of this work was to identify genetic variants potentially involved in familial hypercholesterolemia in 43 genes associated with lipid metabolism disorders. Targeted high-throughput sequencing of lipid metabolism genes was performed (80 subjects with a familial-hypercholesterolemia phenotype). For patients without functionally significant substitutions in the above genes, multiplex ligation-dependent probe amplification was conducted to determine bigger mutations (deletions and/or duplications) in the LDLR promoter and exons. A clinically significant variant in some gene associated with familial hypercholesterolemia was identified in 47.5% of the subjects. Clinically significant variants in the LDLR gene were identified in 19 probands (73.1% of all variants identified in probands); in three probands (11.5%), pathogenic variants were found in the APOB gene; and in four probands (15.4%), rare, clinically significant variants were identified in genes LPL, SREBF1, APOC3, and ABCG5. In 12 (85.7%) of 14 children of the probands, clinically significant variants were detectable in genes associated with familial hypercholesterolemia. The use of clinical criteria, targeted sequencing, and multiplex ligation-dependent probe amplification makes it possible to identify carriers of rare clinically significant variants in a wide range of lipid metabolism genes and to investigate their influence on phenotypic manifestations of familial hypercholesterolemia.

LDLR expression in the cochlea suggests a role in endolymph homeostasis and cochlear amplification

There is now growing evidence that hypercholesterolemia and high serum levels of low-density lipoproteins (LDL) predispose to sensorineural hearing loss. Circulating LDL-cholesterol is delivered to peripheral tissues via LDL receptor (LDLR) -mediated endocytosis. Recently, it has been shown that LDLR gene polymorphisms are associated with higher susceptibility to sudden deafness. These findings suggested that we should investigate the expression of LDLR from the postnatal maturation of the mouse cochlea until adulthood. In the cochlea of newborn mice, we observed that LDLR is mostly expressed in the lateral wall of the cochlea, especially in a band of cells directly facing the cochlear duct. Moreover, LDLR is expressed in the inner and outer hair cells, as well as in the adjacent greater epithelial ridge. In early postnatal stages, LDLR is expressed in the marginal cells of the immature stria vascularis, in the root cells of the spiral ligament, and in the adjacent outer sulcus cells. At the same time, LDLR begins to be expressed in the pillar cells of the immature organ of Corti. From the onset of hearing, LDLR is expressed in the marginal cells of the stria vascularis, in the outer sulcus cells, and in the capillaries of the adjacent spiral ligament. In the organ of Corti, LDLR is expressed in outer pillar cells and Deiters' cells, i.e. in the non-sensory supporting cells that directly surround the outer hair cells. These cells are believed to provide a mechanical coupling with the outer hair cells to modulate electromotility and cochlear amplification. In the stria vascularis of three-month-old mice, LDLR is further expressed in both marginal and intermediate cells. Overall, our results suggest that LDLR is mostly present in cochlear cells that are involved in endolymph homeostasis and cochlear amplification. Further functional studies will be needed to unravel how LDLR regulates extracellular and intracellular levels of cholesterol and lipoproteins in the cochlea, and how it could influence cochlear homeostasis.

Lack of phenotypic additive effect of familial defective apolipoprotein B3531 in familial hypercholesterolaemia

Familial defective apolipoprotein (apo) B (FDB) and familial hypercholesterolaemia (FH) are the two common genetic conditions that cause hypercholesterolaemia. R3531C mutation of the APOB gene is a rare cause of FDB. Individuals with both FDB and FH are rare. A 51-year-old man with hypercholesterolaemia (11.4 mmol/L) and his family were studied. Low-density lipoprotein (LDL) receptor (LDLR) and APOB genes were analysed by direct sequencing. LDL of four subjects were studied in a fibroblast LDL receptor-binding displacement assay. We found a mutation of the LDLR gene (p.Y398X) in the proband and in four other family members: the p.R3531C APOB gene mutation was also found in the proband, his father and his children. The proband and his son were thus compound heterozygotes for both FH and FDB. Double heterozygotes did not show higher cholesterol levels compared to carriers of LDLR gene mutation alone. LDL from one of the carriers of the p.R3531C alone exhibited a binding ability, which was similar to a normal subject. This is the first report in Italy of the p.R3531C mutation, and our results show that this mutation has no effect in LDLR p.Y398X/APOB p.R3531C double heterozygotes.

Mutational Spectrum of LDLR and PCSK9 Genes Identified in Iranian Patients With Premature Coronary Artery Disease and Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a common, yet underdiagnosed, genetic disorder characterized by lifelong elevated low-density lipoprotein cholesterol levels, which can increase the risk of early-onset coronary artery disease (CAD). In the present study, we screened the nucleotide variations of the LDLR and PCSK9 genes, as well as a part of the APOB gene, in Iranian patients with FH and premature CAD to find the genetic cause of the disorder. Fifteen unrelated individuals with a clinical diagnosis of FH and premature CAD were recruited. Direct DNA sequencing was applied to screen the whole coding exons and exon-intron boundaries of the LDLR and PCSK9 genes and the main parts of their introns, together with exon 26 of the APOB gene. The pathogenicity of the identified mutations was investigated via either segregation analyses in the family or in silico predictive software. Six different point mutations (p.Cys148Tyr, p.Cys216Tyr, p.Cys302Trp, p.Cys338Trp, p.Leu479Gln, and p.G593Afs∗72) in LDLR and a double mutation (p.Asp172His and p.Ala53Val) in both LDLR and PCSK9 genes were identified in seven families with clinically diagnosed FH (43%), whereas no pathogenic mutations were found in eight families with clinically diagnosed FH. This study is the first to identify 1 pathogenic mutation in the LDLR gene (c.1014C > G [p.Cys338Trp]) and to cosegregate it from the affected individual in the family. No mutations were found in the APOB gene, whereas several silent mutations/polymorphisms were identified in the LDLR and PCSK9 genes. Genetic testing and reports on nucleotide alterations in the Iranian population are still limited. Our findings not only further confirm the significant role of FH in the incidence of premature CAD but also enlarge the spectrum of LDLR and PCSK9 variations and exhibit the heterogeneity of FH in Iranians. In patients with no mutation in the examined genes, the disease could be begotten either by a polygenic cause or by gene defects occurring in other related genes and regions not targeted in this study.

The Digenic Causality in Familial Hypercholesterolemia: Revising the Genotype-Phenotype Correlations of the Disease

Genetically inherited defects in lipoprotein metabolism affect more than 10 million individuals around the globe with preponderance in some parts where consanguinity played a major role in establishing founder mutations. Mutations in four genes have been so far linked to the dominant and recessive form of the disease. Those players encode major proteins implicated in cholesterol regulation, namely, the low-density lipoprotein receptor (LDLR) and its associate protein 1 (LDLRAP1), the proprotein convertase substilin/kexin type 9 (PCSK9), and the apolipoprotein B (APOB). Single mutations or compound mutations in one of these genes are enough to account for a spectrum of mild to severe phenotypes. However, recently several reports have identified digenic mutations in familial cases that do not necessarily reflect a much severe phenotype. Yet, data in the literature supporting this notion are still lacking. Herein, we review all the reported cases of digenic mutations focusing on the biological impact of gene dosage and the potential protective effects of single-nucleotide polymorphisms linked to hypolipidemia. We also highlight the difficulty of establishing phenotype-genotype correlations in digenic familial hypercholesterolemia cases due to the complexity and heterogeneity of the phenotypes and the still faulty in silico pathogenicity scoring system. We finally emphasize the importance of having a whole exome/genome sequencing approach for all familial cases of familial hyperlipidemia to better understand the genetic and clinical course of the disease.

Highlights from Studies in Cardiovascular Disease Prevention Presented at the Digital 2020 European Society of Cardiology Congress: Prevention Is Alive and Well

PURPOSE OF REVIEW

The review highlights selected studies related to cardiovascular disease (CVD) prevention that were presented at the 2020 European Society of Cardiology (ESC) Congress-The Digital Experience.

RECENT FINDINGS

The studies reviewed include clinical trials on novel RNA interference-based lipid-lowering therapies AKCEA-APOCIII-LRx and vupanorsen (AKCEA-ANGPTL3-LRx); the EVAPORATE trial assessing the effects of icosapent ethyl on coronary plaque volume progression; the LoDoCo2 trial evaluating the efficacy of low-dose colchicine in cardiovascular disease risk reduction among patients with chronic coronary artery disease; as well as the EMPEROR-Reduced trial evaluating cardiovascular and renal outcomes with empagliflozin in patients with heart failure and reduced ejection fraction. In addition, we review the BPLTTC analysis on blood pressure treatment across blood pressure levels and CVD status and discuss findings from the BRACE CORONA study that examined continuing versus suspending angiotensin-converting enzyme inhibitor or angiotensin receptor blockers in patients on these antihypertensive medications who were hospitalized with COVID-19 infection. The studies presented at the 2020 digital ESC Congress highlight the continuing advancements in the field of CVD prevention.

Lipid-Lowering Biotechnological Drugs: from Monoclonal Antibodies to Antisense Therapies-a Clinical Perspective

PURPOSE

While low density lipoprotein cholesterol (LDL-C) remains a key contributor of atherosclerotic cardiovascular disease (ASCVD), additional risk factors identified through epidemiological and genetic studies have ushered in a fertile era of drug discovery in lipid-lowering therapy. Unlike contemporary small molecule medications, many of the novel agents are biologics utilizing monoclonal antibody (mAb) or RNA interference (RNAi) technologies. This report aims to review the evidence to date, focusing on completed and ongoing clinical trials and how these new agents will impact clinical practice.

METHODS

We review data from pertinent studies on lipid-lowering biologics in clinical use or have translated to human studies and are undergoing clinical trials.

RESULTS

Several targets affecting lipid metabolism have been identified to be causally associated with ASCVD including proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3 (ANGPTL3), apolipoprotein C3 (APOC3), and lipoprotein (a) (Lp[a]). Biotechnological modalities that have been developed for these targets include mAb, small interfering RNA (siRNA), and anti-sense oligonucleotide (ASO) agents. Agents such as alirocumab and evolocumab have shown efficacy in risk reduction of ASCVD in cardiovascular outcome trials and have been incorporated into evidence-based practice guidelines. Other agents included in this review are in various stages of clinical trials and have shown significant efficacy in the reduction of lipid parameters.

CONCLUSION

The development of new biologics targeting lipid risk factors will provide clinicians additional tools to reduce the risk for ASCVD. Important factors to consider will be cost-effectiveness and improving methods to personalize treatments to risk factors.

Highlights of Studies in Cardiovascular Disease Prevention Presented at the 2020 American College of Cardiology Annual Scientific Session

PURPOSE OF REVIEW

The review highlights selected studies related to cardiovascular disease (CVD) prevention that were presented at the American College of Cardiology 2020 Virtual Scientific Session (ACC.20)/World Cardiology Congress (WCC).

RECENT FINDINGS

The studies reviewed include clinical trials on the efficacy and safety of alirocumab (Study in Participants with Homozygous Familial Hypercholesterolemia [ODYSSEY HoFH]) and evinacumab in the treatment of homozygous familial hypercholesterolemia (HoFH); Evaluating the Efficacy of E-cigarettes for Smoking Cessation (E3); the use of renal denervation in the treatment of hypertension (SPYRAL HTN-OFF MED PIVOTAL); and the assessment of vericiguat in the treatment of heart failure (A Study of Vericiguat in Participants with Heart Failure with Reduce Ejection Fraction [VICTORIA]). In addition, results from the pooled analysis of phase III trials on inclisiran and secondary analysis examining eicosapentaenoic acid levels and cardiovascular outcomes from the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) were included. Finally, we discuss studies examining the use of polygenic risk score with low density lipoprotein cholesterol (LDL-C) and systolic blood pressure (SBP) on lifetime cardiovascular risk. The studies presented at the ACC.20/WCC represent notable contributions in the field of CVD prevention.

Application of Genome-Wide Association Studies in Coronary Artery Disease

Coronary artery disease (CAD) is a complex disease caused by the combination of environmental and genetic factors. It is one of the leading causes of death and disability in the world. Much research has been focussed on CAD genetic mechanism. In recent years, genome-wide association study (GWAS) has developed rapidly around the world. Medical researchers around the world have successfully discovered a series of CAD genetic susceptibility genes or susceptible loci using medical research strategies, leading CAD research toward a new stage. This paper briefly summarizes the important progress made by GWAS for CAD in the world in recent years, and then analyzes the challenges faced by GWAS at this stage and the development trend of future research, to promote the transformation of genetic research results into clinical practice and provide guidance for further exploration of the genetic mechanism of CAD.

Early diagnosis and treatment of familial hypercholesterolemia

If undiagnosed and untreated, familial hypercholesterolemia can lead to serious cardiac complications, such as premature atherosclerotic cardiovascular disease. NPs should be familiar with the clinical presentation of this inherited metabolic disease to diagnose patients as early as possible and promptly begin treatment that may include lifestyle changes, statin therapy, and/or nonstatin therapy.

Genetic associations between serum low LDL-cholesterol levels and variants in LDLR, APOB, PCSK9 and LDLRAP1 in African populations

Non-communicable diseases, including cardiovascular diseases (CVDs), are increasing in African populations. High serum low density lipoprotein cholesterol (LDL-cholesterol) levels are a known risk factor for CVDs in European populations, but the link remains poorly understood among Africans. This study investigated the associations between serum LDL-cholesterol levels and selected variants in the low density lipoprotein receptor (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin type 9 (PCSK9) and low density lipoprotein receptor adaptor protein 1 (LDLRAP1) genes in some selected African populations. Nineteen SNPs were selected from publicly available African whole genome sequence data based on functional prediction and allele frequency. SNPs were genotyped in 1000 participants from the AWI-Gen, study selected from the extremes of LDL-cholesterol level distribution (500 with LDL-cholesterol>3.5 mmol/L and 500 with LDL-cholesterol<1.1 mmol/L). The minor alleles at five of the six associated SNPs were significantly associated (P<0.05) with lower LDL-cholesterol levels: LDLRAP1 rs12071264 (OR 0.56, 95% CI: 0.39-0.75, P = 2.73x10-4) and rs35910270 (OR 0.78, 95% CI: 0.64-0.94, P = 0.008); APOB rs6752026 (OR 0. 55, 95% CI: 0.41-0.72, P = 2.82x10-5); LDLR: rs72568855 (OR 0.47, 95% CI: 0.27-0.82, P = 0.008); and PCSK9 rs45613943 (OR = 0.72, 95% CI: 0.58-0.88, P = 0.001). The minor allele of the sixth variant was associated with higher LDL-cholesterol levels: APOB rs679899 (OR 1.41, 95% CI: 1.06-1.86, P = 0.016). A replication analysis in the Africa America Diabetes Mellitus (AADM) study found the PCSK9 variant to be significantly associated with low LDL-cholesterol levels (Beta = -0.10). Since Africans generally have lower LDL-cholesterol levels, these LDL-cholesterol associated variants may be involved in adaptation due to unique gene-environment interactions. In conclusion, using a limited number of potentially functional variants in four genes, we identified significant associations with lower LDL-cholesterol levels in sub-Saharan Africans.

Fragment-based design of small molecule PCSK9 inhibitors using simulated annealing of chemical potential simulations

PCSK9 is a protein secreted by the liver that binds to the low-density lipoprotein receptor (LDLR), causing LDLR internalization, decreasing the clearance of circulating LDL particles. Mutations in PCSK9 that strengthen its interactions with LDLR result in familial hypercholesterolemia (FH) and early onset atherosclerosis, while nonsense mutations of PCSK9 result in cardio-protective hypocholesterolemia. These observations led to PCSK9 inhibition for cholesterol lowering becoming a high-interest therapeutic target, with antibody drugs reaching the market. An orally-available small molecule drug is highly desirable, but inhibiting the PCSK9/LDLR protein-protein interaction (PPI) has proven challenging. Alternate approaches to finding good lead candidates are needed. Motivated by the FH mutation data on PCSK9, we found that modeling the PCSK9/LDLR interface revealed extensive electron delocalization between and within the protein partners. Based on this, we hypothesized that compounds assembled from chemical fragments could achieve the affinity required to inhibit the PCSK9/LDLR PPI if they were selected to interact with PCSK9 in a way that, like LDLR, also involves significant fractional charge transfer to form partially covalent bonds. To identify such fragments, Simulated Annealing of Chemical Potential (SACP) fragment simulations were run on multiple PCSK9 structures, using optimized partial charges for the protein. We designed a small molecule, composed of several fragments, predicted to interact at two sites on the PCSK9. This compound inhibits the PPI with 1 μM affinity. Further, we designed two similar small molecules where one allows charge delocalization though a linker and the other doesn’t. The first inhibitor with charge delocalization enhances LDLR surface expression by 60% at 10 nM, two orders of magnitude more potent than the EGF domain of LDLR. The other enhances LDLR expression by only 50% at 1 μM. This supports our conjecture that fragments can have surprisingly outsized efficacy in breaking PPI’s by achieving fractional charge transfer leading to partially covalent bonding.

Genetic testing preferences and intentions in patients with clinically diagnosed familial hypercholesterolemia

PURPOSE

Familial hypercholesterolemia (FH) is a common Mendelian disorder characterized by elevated LDL cholesterol levels, which if untreated can cause premature heart disease. Less than 10% of cases in the United States are diagnosed. This study investigates decision-making factors associated with intentions to have FH genetic testing among patients clinically diagnosed with FH.

METHODS

Fifty-three clinically diagnosed adults with FH and no genetic testing were recruited through the FH Foundation and lipid clinics. Participants completed a survey containing items capturing various reasons to engage in genetic testing.

RESULTS

Exploratory factor analysis of survey items identified three factors: (a) aversion to FH genetic information, (b) curiosity regarding medical/family history, (c) and psychological reassurance. Psychological reassurance was, in turn, the only significant predictor of genetic testing intentions. The positive effect of reassurance on genetic testing intention was moderated by aversion such that individuals who were low in reassurance were more inclined to decline testing if aversion was high.

CONCLUSION

Findings suggest that clinically diagnosed patients' decisions about FH genetic testing are driven principally by psychological reassurance, particularly when low in aversion to FH genetic information.

Efficacy and Safety of Mipomersen: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

AIM

Our aim was to assess the efficacy and safety of mipomersen through a systematic review of the literature and a meta-analysis of the available clinical studies.

METHODS

A systematic literature search in SCOPUS, PubMed Medline, ISI Web of Science and Google Scholar databases was conducted up to January 20, 2019, in order to identify clinical trials assessing the effect of mipomersen on lipoproteins, and the safety profile of mipomersen. Effect sizes for lipid changes were expressed as weighted mean differences (WMD) and 95% confidence intervals (CI). For safety analysis, odd ratios (OR) and 95% CI were calculated using the Mantel-Haenszel method. Data were pooled from 13 clinical studies comprising 49 arms, which included 1053 subjects overall, with 729 in the active-treated arm and 324 in the control arm.

RESULTS

Meta-analysis of data suggested that mipomersen significantly reduced low-density lipoprotein cholesterol (WMD - 1.52, 95% CI - 1.85 to - 1.19; p < 0.001), total cholesterol (WMD - 1.55, 95% CI - 1.97 to - 1.13; p < 0.001), non-high-density lipoprotein cholesterol (non-HDL-C) (WMD - 1.66, 95% CI - 2.06 to - 1.27; p < 0.001), lipoprotein(a) (WMD - 0.99, 95% CI - 1.37 to - 0.62; p < 0.001), apolipoprotein B (WMD - 1.66, 95% CI - 2.04 to - 1.27; p < 0.001), triglycerides (WMD -0.61, 95% CI - 0.76 to - 0.46, p < 0.001), very-low-density lipoprotein cholesterol (WMD - 0.58, 95% CI - 0.73 to - 0.43; p < 0.001) and apolipoprotein A-I (WMD - 0.25, 95% CI - 0.51 to - 0.001; p = 0.049) without affecting HDL-C levels (WMD 0.11, 95% CI - 0.03 to 0.26; p = 0.124). However, treatment with mipomersen was positively associated with an increased risk of discontinuation of treatment (OR 3.02, 95% CI 1.96-4.65; p < 0.001), injection-site reaction (OR 11.41, 95% CI 7.88-16.52; p < 0.001), hepatic steatosis (OR 4.96, 95% CI 1.99-12.39; p = 0.001), hepatic enzymes elevation (OR 3.61, 95% CI 2.09-6.24; p < 0.001) and flu-like symptoms (OR 2.02, 95% CI 1.45-2.81; p < 0.001).

CONCLUSION

Despite favourable effects on the lipid profile, some concerns are reinforced from the safety profile. As a matter of fact, mipomersen therapy is more likely discontinued and associated with increased risk of injection-site reactions, hepatic steatosis, hepatic enzyme elevation, and flu-like symptoms.

Ser-Phosphorylation of PCSK9 (Proprotein Convertase Subtilisin-Kexin 9) by Fam20C (Family With Sequence Similarity 20, Member C) Kinase Enhances Its Ability to Degrade the LDLR (Low-Density Lipoprotein Receptor)

OBJECTIVE

PCSK9 (proprotein convertase subtilisin-kexin 9) enhances the degradation of the LDLR (low-density lipoprotein receptor) in endosomes/lysosomes. This study aimed to determine the sites of PCSK9 phosphorylation at Ser-residues and the consequences of such posttranslational modification on the secretion and activity of PCSK9 on the LDLR. Approach and Results: Fam20C (family with sequence similarity 20, member C) phosphorylates serines in secretory proteins containing the motif S-X-E/phospho-Ser, including the cholesterol-regulating PCSK9. In situ hybridization of Fam20C mRNA during development and in adult mice revealed a wide tissue distribution, including liver, but not small intestine. Here, we show that Fam20C phosphorylates PCSK9 at Serines 47, 666, 668, and 688. In hepatocytes, phosphorylation enhances PCSK9 secretion and maximizes its induced degradation of the LDLR via the extracellular and intracellular pathways. Replacing any of the 4 Ser by the phosphomimetic Glu or Asp enhanced PCSK9 activity only when the other sites are phosphorylated, whereas Ala substitutions reduced it, as evidenced by Western blotting, Elisa, and LDLR-immunolabeling. This newly uncovered PCSK9/LDLR regulation mechanism refines our understanding of the implication of global PCSK9 phosphorylation in the modulation of LDL-cholesterol and rationalizes the consequence of natural mutations, for example, S668R and E670G. Finally, the relationship of Ser-phosphorylation to the implication of PCSK9 in regulating LDL-cholesterol in the neurological Fragile X-syndrome disorder was investigated.

CONCLUSIONS

Ser-phosphorylation of PCSK9 maximizes both its secretion and activity on the LDLR. Mass spectrometric approaches to measure such modifications were developed and applied to quantify the levels of bioactive PCSK9 in human plasma under normal and pathological conditions.

Postprandial changes in gene expression of cholesterol influx and efflux mediators after intake of SFA compared with n-6 PUFA in subjects with and without familial hypercholesterolaemia: secondary outcomes of a randomised controlled trial

The long-term cholesterol-lowering effect of replacing intake of SFA with PUFA is well established, but has not been fully explained mechanistically. We examined the postprandial response of meals with different fat quality on expression of lipid genes in peripheral blood mononuclear cells (PBMC) in subjects with and without familial hypercholesterolaemia (FH). Thirteen subjects with FH (who had discontinued lipid-lowering treatment ≥4 weeks prior to both test days) and fourteen normolipidaemic controls were included in a randomised controlled double-blind crossover study with two meals, each with 60 g of fat either mainly SFA (about 40% energy) or n-6 PUFA (about 40% energy). PBMC were isolated in fasting, and 4 and 6 h postprandial blood samples. Expression of thirty-three lipid genes was analysed by reverse transcription quantitative PCR. A linear mixed model was used to assess postprandial effects between meals and groups. There was a significant interaction between meal and group for MSR1 (P = 0·03), where intake of SFA compared with n-6 PUFA induced a larger reduction in gene expression in controls only (P = 0·01). Intake of SFA compared with n-6 PUFA induced larger reductions in gene expression levels of LDLR and FADS1/2, smaller increases of INSIG1 and FASN, and larger increases of ABCA1 and ABCG1 (P = 0·01 for all, no group interaction). Intake of SFA compared with n-6 PUFA induced changes in gene expression of cholesterol influx and efflux mediators in PBMC including lower LDLR and higher ABCA1/G1, potentially explaining the long-term cholesterol-raising effect of a high SFA intake.

Delayed postprandial TAG peak after intake of SFA compared with PUFA in subjects with and without familial hypercholesterolaemia: a randomised controlled trial

Postprandial hypertriacylglycerolaemia is associated with an increased risk of developing CVD. How fat quality influences postprandial lipid response is scarcely explored in subjects with familial hypercholesterolaemia (FH). The aim of this study was to investigate the postprandial response of TAG and lipid sub-classes after consumption of high-fat meals with different fat quality in subjects with FH compared with normolipidaemic controls. A randomised controlled double-blind cross-over study with two meals and two groups was performed. A total of thirteen hypercholesterolaemic subjects with FH who discontinued lipid-lowering treatment 4 weeks before and during the study, and fourteen normolipidaemic controls, were included. Subjects were aged 18-30 years and had a BMI of 18·5-30·0 kg/m2. Each meal consisted of a muffin containing 60 g (70 E%) of fat, either mainly SFA (40 E%) or PUFA (40 E%), eaten in a random order with a wash-out period of 3-5 weeks between the meals. Blood samples were collected at baseline (fasting) and 2, 4 and 6 h after intake of the meals. In both FH and control subjects, the level of TAG and the largest VLDL sub-classes peaked at 2 h after intake of PUFA and at 4 h after intake of SFA. No significant differences were found in TAG levels between meals or between groups (0·25≤P≤0·72). The distinct TAG peaks may reflect differences in the postprandial lipid metabolism after intake of fatty acids with different chain lengths and degrees of saturation. The clinical impact of these findings remains to be determined.

The frequency of familial hypercholesterolemia amongst patients in the outpatient clinic of the tertiary specialized cardiology center in Kyrgyzstan

BACKGROUND

Familial hypercholesterolemia (FH) is frequently underdiagnosed. Prevalence of the FH in Kyrgyzstan is unknown.

AIM

to investigate the prevalence of FH amongst patients in the outpatient settings of the tertiary cardiologic center in Kyrgyzstan.

METHODS

Retrospective observational study was conducted using the database of the laboratory of biochemistry and electronic database of outpatient department of the National Center of Cardiology and internal diseases. Patient with the level of total cholesterol (TC) ≥7,5 mmol/l and/or low density lipoprotein cholesterol (LDL-C) ≥ 4,9 mmol/l without signs of secondary hyperlipidemia were included in the analysis. FH was defined using Dutch Lipid Clinic Network criteria.

RESULTS

according to the laboratory database levels of TC and LDL-C was conducted in 8281patiens and 525 of them had a high lipid levels. After exclusion of patients with secondary hyperlipidemia, high level of triglycerides and pregnant women - 91 patients were included in the analysis. Among them the definite FH was revealed in 2 (2,2%) patients, probable FH - in 6 (6,6%), and possible in 76 (83,5%), and in 7,7% there were no signs of FH.

CONCLUSION

Frequency of potential FH (definite and probable) in our analysis was low. To understand the real prevalence of FH in a Kyrgyz population epidemiological study is needed.

Association between Heavy Metals, Bisphenol A, Volatile Organic Compounds and Phthalates and Metabolic Syndrome

The incidence of metabolic syndrome (MetS), which causes heart disease and stroke, has increased significantly worldwide. Although many studies have revealed the relationship between heavy metals (cadmium, mercury, and lead), the sum of metabolites of di(2-ethylhexyl) phthalate (DEHP), and MetS, the results remain inconsistent. No study has reported the association between various volatile organic compounds (VOCs) and phthalate metabolites with MetS. This cross-sectional study of a representative sample of adult South Koreans aimed to evaluate the relationship between heavy metals, VOC metabolites, phthalate metabolites, bisphenol A and MetS after adjusting for demographic variables. Data from the Korean National Environmental Health Survey II (2012–2014) (n = 5251) were used in the analysis. Multiple logistic regression analysis was performed for MetS with log-transformed hazardous material quartiles after covariate adjustment. Urine muconic acid (MuA) and mono- (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) levels were significantly associated with MetS after adjusting for confounders (odds ratio: 1.34 and 1.39, respectively). Urine MuA and MEHHP levels were significantly associated with MetS. Because of the rarity of this study, which investigated the relationship between each VOC and phthalate metabolite with MetS and the strict definition of all indirect measures of MetS components, further research is needed.

Reverse Cascade Screening for Familial Hypercholesterolemia

PROBLEM

Cardiovascular disease (CVD) is the leading cause of death in the U.S. and in most Western countries. Early identification and treatment of individuals with elevated levels of atherogenic cholesterol, a major contributor to CVD, have been shown to be effective and safe in reducing premature morbidity and mortality, especially in familial hypercholesterolemia (FH). Cholesterol screening of youth also provides a unique means of identifying affected family members through reverse cascade screening (RCS).

ELIGIBILITY CRITERIA

A PubMed review of all relevant articles from 2000 to 2016 was conducted of familial hypercholesterolemia and cholesterol screening of youth.

RESULTS

We provide an overview of cholesterol screening, outline the role of the pediatric nurse in the lipid clinic, and discuss effectiveness and potential barriers, including cost and confidentiality considerations of RCS.

CONCLUSIONS

Early identification and effective intervention of youth with FH, including adoption of a heart-healthy lifestyle, has the potential of 1) markedly reducing or eliminating atherosclerotic cardiovascular disease and related events in future generations and 2) provides a unique means of identifying affected family members.

IMPLICATIONS

Pediatric nurses play a vital role in the education and care coordination of children diagnosed with FH and screening of relatives. Identification of a child with FH with effective screening of relatives combines the benefits of universal and cascade screening, and has the potential of detecting all living cases of FH. While potentially providing significant benefit to those at risk for premature CVD, a RCS program needs to carefully consider ethical, psychological, and financial implications as well.

Application of expanded genetic analysis in the diagnosis of familial hypercholesterolemia in patients with very early-onset coronary artery disease

BACKGROUND

Patients with monogenic familial hypercholesterolemia (FH) have high risk for coronary artery disease (CAD). A recent FH Expert Panel suggested that FH was underdiagnosed and undertreated which needs early diagnosis. Moreover, the proportion of DNA-confirmed FH patients hospitalized with very early-onset (≤ 35 years) CAD remains uncertain.

METHODS

One hundred and five patients with age ≤ 35 years and LDL-C ≥ 3.4 mmol/L were tested for 9 genes (LDLR, APOB, PCSK9, APOE, STAP1, LIPA, LDLRAP1, ABCG5/8). Dutch Lipid Clinic Network (DLCN) and Simon Broome (SB) criteria for FH were also performed.

RESULTS

The prevalence of genetically confirmed FH was 38.1% (n = 40) in 105 patients. DLCN categorized 26.7% patients to probable and definite FH while SB identified 17.1% of patients with possible to definite FH. Twenty-five (62.5%) and seventeen (42.5%) patients with pathogenic mutations were undiagnosed according to SB and DLCN criteria. FH variant carriers, especially homozygotes, had significantly higher plasma LDL-C levels. The best LDL-C threshold for genetically confirmed FH was 4.56 mmol/L in the present study.

CONCLUSIONS

FH is really a common cause for very young CAD patients (≤ 35 years) with a 38.1% of causative mutations in China and best LDL-C threshold for predicting mutations was 4.56 mmol/L. The underdiagnostic rate of clinical criteria was around 42.5-62.5%, suggesting that the expanded genetic testing could indeed promote the diagnosis of FH.

Progress and perspectives in plant sterol and plant stanol research

Current evidence indicates that foods with added plant sterols or stanols can lower serum levels of low-density lipoprotein cholesterol. This review summarizes the recent findings and deliberations of 31 experts in the field who participated in a scientific meeting in Winnipeg, Canada, on the health effects of plant sterols and stanols. Participants discussed issues including, but not limited to, the health benefits of plant sterols and stanols beyond cholesterol lowering, the role of plant sterols and stanols as adjuncts to diet and drugs, and the challenges involved in measuring plant sterols and stanols in biological samples. Variations in interindividual responses to plant sterols and stanols, as well as the personalization of lipid-lowering therapies, were addressed. Finally, the clinical aspects and treatment of sitosterolemia were reviewed. Although plant sterols and stanols continue to offer an efficacious and convenient dietary approach to cholesterol management, long-term clinical trials investigating the endpoints of cardiovascular disease are still lacking.

Characteristics and management of 1093 patients with clinical diagnosis of familial hypercholesterolemia in Greece: Data from the Hellenic Familial Hypercholesterolemia Registry (HELLAS-FH)

BACKGROUND AND AIMS

Although familial hypercholesterolemia (FH) is one of the most common genetic disorders, it remains largely underdiagnosed and undertreated. The Hellenic Atherosclerosis Society has established the Hellenic Familial Hypercholesterolemia (HELLAS-FH) Registry, part of the Familial Hypercholesterolemia Studies Collaboration (FHSC), to evaluate the characteristics and management of patients with FH in Greece.

METHODS

Patients with diagnosed FH were recruited by a network of sites throughout Greece. The prevalence of cardiovascular disease (CVD) risk factors, as well as management of FH, was recorded.

RESULTS

This interim analysis included 1093 patients (556 male; 950 adults). The median age of FH diagnosis was 42.2 years (interquartile range 27.2-53.0). A family history of CVD was present in 47.8%, while 21.1% of patients had a personal history of CVD. At diagnosis, low-density lipoprotein cholesterol (LDL-C) was 241 ± 76 mg/dL in adults and 229 ± 57 mg/dL in children. Overall, 63.1% of the patients were receiving hypolipidemic drug treatment, mainly statins, at inclusion in the registry. Mean LDL-C of patients receiving drug treatment was 154 ± 76 mg/dL in adults and 136 ± 47 mg/dL in children. The majority of treated patients (87.9%) did not achieve LDL-C targets.

CONCLUSIONS

FH in Greece is characterized by a significant delay in diagnosis and a high prevalence of both family and personal history of established CVD. The vast majority of FH patients do not achieve LDL-C targets. Improved awareness and management of FH are definitely needed.

Predictors of Family Enrollment in a Genetic Cascade Screening Program for Familial Hypercholesterolemia

Background

Genetic cascade screening is the most cost-effective method for the identification of individuals with familial hypercholesterolemia (FH), but the best strategies for the enrollment of at-risk individuals in a FH screening program are not fully known.

Objective

The aim of this study is to identify the best predictors of familial enrollment into genetic screening, using features derived from tested probands.

Methods

One hundred and eighty-three index-cases (ICs) with a positive genetic result that had relatives screened from 01/2011 to 07/2015 were included. The response variable was the number of relatives for each enrolled IC. All variables in the study were based on ICs’ derived clinical and socioeconomical features. The effect size of predictor variables were obtained through a general linear model using a negative binomial regression link function. Significance was considered with a p < 0.05.

Results

Mean IC age when enrolling into the program was 50 years old; 78.1% of individuals reported knowledge of relatives with dyslipidemia. Mean baseline LDL-cholesterol level was 316 ± 90 mg/dL. Referral origin through the cascade program website vs. tertiary care, IC LDL-cholesterol and familial history of high LDL-cholesterol levels were independent predictors associated with a higher number of enrolled relatives.

Conclusions

Our data suggest that FH cascade screening programs can predict family enrollment based on IC features. This information may be useful for devising better and more effective screening approaches for at-risk individuals.

A Half-Century History of Applications of Antisense Oligonucleotides in Medicine, Agriculture and Forestry: We Should Continue the Journey

Antisense oligonucleotides (ASO), short single-stranded polymers based on DNA or RNA chemistries and synthesized in vitro, regulate gene expression by binding in a sequence-specific manner to an RNA target. The functional activity and selectivity in the action of ASOs largely depends on the combination of nitrogenous bases in a target sequence. This simple and natural property of nucleic acids provides an attractive route by which scientists can create different ASO-based techniques. Over the last 50 years, planned and realized applications in the field of antisense and nucleic acid nanotechnologies have produced astonishing results and posed new challenges for further developments, exemplifying the essence of the post-genomic era. Today the majority of ASOs are chemically modified and/or incorporated within nanoparticles to enhance their stability and cellular uptake. This review critically analyzes some successful cases using the antisense approach in medicine to address severe diseases, such as Duchenne muscular dystrophy and spinal muscular atrophy, and suggests some prospective directions for future research. We also examine in detail the elaboration of unmodified insect-specific DNA insecticides and RNA preparations in the areas of agriculture and forestry, a relatively new branch of ASO that allows circumvention of the use of non-selective chemical insecticides. When considering the variety of successful ASO modifications with an efficient signal-to-noise ratio of action, coupled with the affordability of in vitro oligonucleotide synthesis and post-synthesis procedures, we predict that the next half-century will produce a fruitful yield of tools created from effective ASO-based end products.

Multivariate analysis for coronary heart disease in heterozygote familial hypercholesterolemia patients

AIM

rs599839 polymorphism has been related with low levels of cholesterol and reduced coronary heart disease (CHD).

METHODS

We investigated the frequency of this polymorphism in patients with heterozygous familial hypercholesterolemia (HeFH) in the Spanish familial hypercholesterolemia cohort, 230 with and 202 without CHD. Results & discussion: A lower G-allele prevalence was observed in HeFH patients with CHD with respect to controls, 35 versus 45%, respectively (p = 0.029), suggesting a protective effect. However, it was found that there was no association between rs599839 alleles and CHD in the multivariate analysis.

CONCLUSION

The frequency of the protective G-allele of the rs599839 polymorphism was lower in HeFH patients with CHD compared with those HeFH patients without CHD. However, its role in HeFH may be masked by very high levels of cholesterol.

Association between lipoprotein (a) and proprotein convertase substilisin/kexin type 9 in patients with heterozygous familial hypercholesterolemia: A case-control study

BACKGROUND

Recent data have suggested an important role of lipoprotein (a) [Lp(a)] and proprotein convertase substilisin/kexin type 9 (PCSK9) in the development of atherosclerotic cardiovascular disease (ASCVD) in both general population and family hypercholesterolemia (FH), while the relation of Lp(a) to PCSK9 has not been examined.

OBJECTIVE

The aim of the present study was to investigate the association between plasma PCSK9 and Lp(a)in patients with heterozygous FH (HeFH).

METHODS

Two hundred and fifty-five molecularly confirmed patients with HeFH were compared to 255 age- and gender-matched non-FH controls. Plasma PCSK9 and Lp(a) concentrations were measured using ELISA and immunoturbidimetric method respectively, and finally their association was assessed.

RESULTS

Both plasma PCSK9 and Lp(a) levels were significantly higher in patients with HeFH compared to control group (p<0.001). Besides, the Lp(a) concentration and percentage of Lp(a)≥300mg/L were increased by PCSK9 tertiles in HeFH group (both p<0.05) while not in control group. In partial correlation analysis, Lp(a) was associated with PCSK9 (r=0.254, p<0.001) in HeFH group but not in control, which were further confirmed by multivariable linear regression analysis. Furthermore, significant associations between Lp(a) and PCSK9 were also found in subgroups of HeFH group irrespective of definite or probable FH, with and without coronary artery disease (CAD), and with statin or not.

CONCLUSIONS

Plasma Lp(a) level was associated with PCSK9 in patients with HeFH alone, suggesting that much about the interaction of PCSK9 with Lp(a) in FH need further explorations.

An insight into familial hypercholesterolemia in Greece: rationale and design of the Hellenic Familial Hypercholesterolemia Registry (HELLAS-FH)

Familial hypercholesterolemia (FH) is the most common metabolic genetic disorder. It is estimated that around 13 million people worldwide have FH. At the same time, only 25% of FH patients have been diagnosed. Moreover, these patients are often undertreated. The true prevalence of FH in Greece is unknown, but it is estimated that there are at least 40,000 FH patients nationwide pointing to a prevalence of 1:250. Patients with FH are at a high risk for cardiovascular events and death at an early age. Therefore, prompt detection of these patients is of pivotal importance in order to implement appropriate preventive measures at a young age. Patient registries are a powerful tool for recording and monitoring a disease and promoting clinical practices, thus contributing to improved outcomes and reduction of healthcare costs. National registries of FH patients have been a success in the Netherlands, Spain and Wales. As Greece did not have a national FH registry, the Hellenic Atherosclerosis Society has organized, established and funded the Hellenic Familial Hypercholesterolemia (HELLAS-FH) national registry in order to promote a better understanding of FH in our country.

Ethnicity, lipids and cardiovascular disease

PURPOSE OF REVIEW

The prevalence of cardiovascular disease differs among ethnic groups and along geographic boundaries. At present, most of the projected increase in mortality from cardiovascular disease occurs in sub-Saharan African, Chinese and Southeast Asian populations. Ethnic disparities in the prevalence of cardiovascular disease coincide with quantitative and qualitative differences in risk factors for cardiovascular disease. High plasma cholesterol is one of the most important preventable causes of ischemic heart disease.

RECENT FINDINGS

The current review summarizes recent evidence on ethnic differences in ischemic heart disease and its correlates with genetic and acquired differences in plasma lipid and lipoprotein levels. The nature of ethnic differences in plasma lipid levels, apolipoprotein L1 en lipoprotein(a) [Lp(a)] is outlined, and the effects of lipid-lowering therapy and future efforts and challenges regarding implementation are discussed.

SUMMARY

Ethnic differences in HDL-cholesterol (HDL-C), triglyceride levels and Lp(a) may impact ethnic differences in cardiovascular disease and result in higher residual risk during lipid-lowering therapy. Further efforts should be made to stimulate the use of statins in both high-income and low-income countries and study their effects in individuals with different ethnic backgrounds.