New Approaches in Detection and Treatment of Familial Hypercholesterolemia

Potentials of artificial intelligence in familial hypercholesterolemia: Advances in screening, diagnosis, and risk stratification for early intervention and treatment

Familial hypercholesterolemia (FH) poses a global health challenge due to high incidence rates and underdiagnosis, leading to increased risks of early-onset atherosclerosis and cardiovascular diseases. Early detection and treatment of FH is critical in reducing the risk of cardiovascular events and improving the long-term outcomes and quality of life for affected individuals and their families. Traditional therapeutic approaches revolve around lipid-lowering interventions, yet challenges persist, particularly in accurate and timely diagnosis. The current diagnostic landscape heavily relies on genetic testing of specific LDL-C metabolism genes, often limited to specialized centers. This constraint has led to the adoption of alternative clinical scores for FH diagnosis. However, the rapid advancements in artificial intelligence (AI) and machine learning (ML) present promising solutions to these diagnostic challenges. This review explores the intricacies of FH, highlighting the challenges that are encountered in the diagnosis and management of the disorder. The revolutionary potential of ML, particularly in large-scale population screening, is highlighted. Applications of ML in FH screening, diagnosis, and risk stratification are discussed, showcasing its ability to outperform traditional criteria. However, challenges and ethical considerations, including algorithmic stability, data quality, privacy, and consent issues, are crucial areas that require attention. The review concludes by emphasizing the significant promise of AI and ML in FH management while underscoring the need for ethical and practical vigilance to ensure responsible and effective integration into healthcare practices.

Genetic testing for familial hypercholesterolemia in Quebec, Canada: a single-centre retrospective cohort study

BACKGROUND

Familial hypercholesterolemia (FH) is associated with premature atherosclerotic cardiovascular disease caused by elevated low-density lipoprotein cholesterol (LDL-C) levels. We determined the impact of a full next-generation sequencing (NGS) genetic panel on reclassification of patients with a clinical diagnosis of FH in Quebec compared to the partial genetic panel currently offered by the Quebec Ministère de la Santé et des Services sociaux (Ministry of Health and Social Services) (MSSS), which includes 11 variants that are common in French Canadians.

METHODS

We conducted a retrospective cohort study in a subgroup of patients in the Canadian FH Registry seen at the McGill University Health Centre Preventive Cardiology/Lipid Clinic, Montréal, between September 2017 and September 2021 who were clinically diagnosed with severe hypercholesterolemia, probable FH or definite FH according to the Canadian definition of FH. Next-generation sequencing of the LDLR, APOB and PCSK9 genes, and multiplex ligation-dependent probe amplification of the LDLR gene to detect genetic variants, were performed.

RESULTS

Among 335 consecutive patients with heterozygous FH (184 men [54.9%] and 151 women [45.1%]), the baseline LDL-C level was 6.96 (standard deviation 1.79) mmol/L. Patients identified through cascade screening were 11 years younger on average than index patients, and smaller proportions presented to the clinic with cardiovascular risk factors. A pathogenic FH variant was identified in 169 (73.8%) of the 229 patients who underwent genetic testing; the majority had variants in the LDLR (146 [86.4%]) or APOB (24 [14.2%]) gene. The genetic panel offered by the MSSS accounted for only 48% of the variants identified with the full NGS panel. Of the 229 patients, 90 (39.3%, 95% confidence interval 32.9%-46.0%) were reclassified from a clinical diagnosis of probable FH to definite FH after genetic screening with a full FH panel.

INTERPRETATION

Genetic testing in patients suspected of having FH provided diagnostic certainty and permitted many patients with a clinical diagnosis of probable FH to be reclassified as having definite FH. Genetic screening allows for increased identification of patients with FH and may therefore help reduce the burden of cardiovascular disease and mortality rates among Canadians with FH. Trial registration: ClinicalTrials.gov, no. NCT02009345.

Achieving Lower LDL-C Levels After a Recent Myocardial Infarction Might Be Associated with Lower Healthcare Resource Use and Costs in Spain

INTRODUCTION

There is little evidence on the relationship between achieved low-density lipoprotein cholesterol (LDL-C) levels and costs in patients on lipid-lowering therapy (LLT). We described healthcare resource use and costs (direct and indirect) by achieved LDL-C in patients receiving LLT after a recent myocardial infarction (MI) in Spain.

METHODS

This was a retrospective observational study of anonymized electronic medical records from seven regions in Spain (BIG-PAC^® database; n = 1.9 million). Eligible patients were adults (≥ 18 years) hospitalized for an MI between January 2015 and December 2017, treated with a statin and/or ezetimibe, and having recorded LDL-C values at baseline and during follow-up. Healthcare resource use and direct and indirect costs (in 2018, €) were described by achieved LDL-C levels during a follow-up of 18 months.

RESULTS

Of 6025 patients (mean age, 69.7 years; 77% male), only 11% achieved LDL-C goals as defined in the 2016 ESC/EAS guidelines (< 70 mg/dL), and just 1% reached the lower target (< 55 mg/dL) in the current 2019 guidelines. Achieving lower LDL-C levels translated to lower healthcare resource use and costs. Mean total (direct and indirect) costs ranged from €5044 for patients with LDL-C < 55 mg/dL to €7567 for patients with LDL-C ≥ 130 mg/dL.

CONCLUSION

Very few patients achieved recommended LDL-C goals despite using LLT. Achieving lower LDL-C levels after an MI might be associated with lower healthcare resource use and costs. Use of more intensive LLT, leading to greater reductions in LDL-C, could therefore be beneficial both from a clinical and an economic perspective.

The Progression of Treatment for Refractory Hypercholesterolemia: Focus on the Prospect of Gene Therapy

Refractory hypercholesterolemia (RH), including homozygous familial hypercholesterolemia (HoFH) and compound heterozygous familial hypercholesterolemia, is characterized by high levels of low-density lipoprotein cholesterol (LDL-C) despite existing cholesterol-lowering methods at maximal tolerable doses. Patients with RH have early onset and higher risk of atherosclerotic cardiovascular disease (ASCVD) under insufficient treatment. Therefore, it is urgent to seek new therapies to maintain the blood lipids in refractory hyperlipidemia at normal levels. Currently, new cholesterol-lowering strategies are on the market, not only at the protein level [i.e., bempedoic acid (inhibiting ATP-citrate lyase), alirocumab and evolocumab (monoclonal antibodies against PCSK9), evinacumab (monoclonal antibody against ANGPTL3)] but also at the transcript level [i.e., mipomersen (antisense oligonucleotide inhibiting ApoB), inclisiran (siRNA targeting PCSK9)], providing more options for RH patients to achieve their lipid-lowering targets. More RNA-based therapies targeting RH-related genes have been designed for the treatment. However, for a proportion of patients, especially those with LDLR deficiency, the available treatments are still insufficient. More recently, emerging genome engineering based on CRISPR/Cas9 techniques, and advanced delivery technologies such as lentiviral vectors, adenoviral vectors, adeno-associated viral vectors, lipid nanoparticles, and exosomes are being rapidly developed and implemented as novel therapies for RH. Gene therapy targeting RH-related genes has been successfully conducted in cells, mice, and non-human primates with high efficacy in lipid lowering and good tolerability. Especially the new generation of genome editing technique, base editing, performed in vivo with ideal lipid-lowering effect and limited occurrence of unwanted results. Excitingly, a phase I/II clinical study of LDLR gene replacement has been recently completed in RH patients, likely to be employed in clinical practice in the future. Furthermore, new targets for cholesterol reduction such as REV-ERB, G protein-coupled receptor, Ubiquitin specific peptidase 20 are continually being developed. This narrative review updates recent advances in treatment for RH, summarizes related clinical trials and preclinical studies, especially on the prospect of gene therapy.

Familial Hypercholesterolemia in Patients with Acute Coronary Syndrome: Genetic Insights from EXPLORE-J

Aim: Genetic testing can provide a definitive diagnosis of familial hypercholesterolemia (FH). However, accessibility of genetic testing may be limited in certain countries where it is not considered “standard of care,” including Japan. In addition, mutations responsible for FH cannot be identified in approximately 30% of patients.

Methods: EXPLORE-J is a multicenter, prospective, observational study of patients presenting with acute coronary syndrome (ACS). The genetic data were analyzed and adjudicated as pathogenic, indeterminate, or nondetectable pathogenic variant.

Results: Of 1,944 patients, 431 underwent genetic screening. Overall, most patients had nonpathogenic variants ofLDLR,LDLRAP1, orPCSK9 (n=396, 91.9%). Of the 25 (5.8%) patients with pathogenic variants, variants of theLDLR gene and thePCSK9 gene were seen in 10 and 15 patients, respectively. Indeterminate variants were observed in 10 (2.3%) patients. Of the 431 patients, eight (1.9%) met the criteria for a diagnosis of FH using the Japanese Atherosclerosis Society (JAS) 2017 guidelines. When genetic data were incorporated, 33 (7.7%) patients met the JAS guidelines. No patients with FH pathogenic variants satisfied the JAS clinical criteria for a diagnosis of FH.

Conclusions: The results revealed a higher prevalence of genetic mutations of FH among Japanese patients with ACS and a low sensitivity of the FH diagnostic criteria of the JAS 2017 guidelines. These findings highlight the difficulties of FH diagnosis in patients with ACS in the acute phase and suggest the importance of genetic testing and family history.

Advances in familial hypercholesterolaemia in children

Familial hypercholesterolaemia is a common, dominantly inherited disease that results in high concentrations of low-density lipoprotein cholesterol and in premature cardiovascular disease. To prevent cardiovascular disease and premature mortality, patients with the condition need to be identified and to start treatment early in life. In this Review, we discuss the treatment of heterozygous and homozygous familial hypercholesterolaemia in children, including lifestyle modifications, current pharmacological treatment options, and promising novel lipid-lowering treatments. In particular, these new therapies are expected to improve outcomes for patients with severe heterozygous familial hypercholesterolaemia or statin intolerance. For patients with homozygous familial hypercholesterolaemia, lipoprotein apheresis is currently the most valuable therapy available, but new approaches might reduce the need for this effective yet invasive, time-consuming, and expensive treatment.

Evaluation of cardiovascular risk factors in patients with familial hypercholesterolemia from the North-Eastern area of Romania

Background

Familial hypercholesterolemia(FH) is one of the most frequent and important monogenic cholesterol pathologies. Traditional and non-traditional cardiovascular risk factors increase the prevalence of atherosclerotic cardiovascular disease(ASCVD) in this population. The aims of the study were: (a) to identify FH patients in the North-Eastern part of Romania and to analyze demographic, clinical and paraclinical data (b) to evaluate the risk of new cardiovascular events at follow-up in FH patients stratified by lipid-lowering agents.

Methods

This first prospective study in the North-Eastern part of Romania was carried out between October 2017 and October 2019; out of 980 patients with dyslipidemia evaluated with the Dutch Lipid Network(DLCN) and Simon Broome(SM) scores, 61 patients with DLCN score above 3 and possible/probable FH(SM score) were included.

Results

Nine hundred-eighty patients were examined and 61 (6.2%) were received the clinical diagnosis of FH. The mean age was 48.5±12.5 years, with more female patients than male patients (63.9% versus 36%). Hypertension was the main cardiovascular risk factor for both genders, followed by physical inactivity and obesity for the female group and active smoking for the male group. The measured DLCN score recorded: “possible” FH identified in 39.4%, “probable” FH in 45.9% and “definite” FH in 14.7%. The effective lipid-lowering drugs used were statin alone and statin in association with fenofibrate, which improved both the lipid profile values and the subclinical atherosclerosis markers (ankle-brachial index, carotid intima-media thickness and high-sensitivity C-reactive protein). New ASCVDs that emerged during the study were most commonly represented by coronary heart disease and stroke. At the same time, the new cardiovascular events were delayed in patients receiving the lipid-lowering drugs, without significant differences between them.

Conclusions

In patients with suspected FH, the lipid-lowering agents during the follow-up period delayed the new cardiovascular events, yet failed to reach the goals proposed by the guidelines.

Proprotein convertase subtilisin/kexin type 9 inhibition as the next statin?

PURPOSE OF REVIEW

Despite the wide use of statins and other LDL-cholesterol (LDL-C)-lowering therapies, atherosclerotic cardiovascular disease remains an important cause of mortality and morbidity. Here, we discuss efficacy, side effects and convenience of current and future therapies inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9).

RECENT FINDINGS

Clinical trials with mAbs administered every 2-4 weeks and small interfering RNAs given two to four times per year have consistently demonstrated substantial LDL-C-lowering (40-60%) and improved outcome when added to existing lipid-lowering therapies. Pleiotropic effects of PCSK9 inhibition are somewhat different from those observed with statin treatment as evidenced by reduced levels of triglycerides and lipoprotein(a) with no apparent effect on inflammatory markers in patients treated with PCSK9 inhibitors. Treatment with mAb and small interfering RNA are associated with a high-cost, however, small molecules and vaccines may improve cost and convenience if development of these are successful.

SUMMARY

PCSK9 inhibitors are currently considered to be an add-on therapy and whether these drugs will be used as stand-alone and/or as a first choice is dependent on clinical readouts from ongoing and future trials, real-world evidence, convenience and treatment costs.

Analysis of Differentially Expressed Genes and Molecular Pathways in Familial Hypercholesterolemia Involved in Atherosclerosis: A Systematic and Bioinformatics Approach

Background and Aims: Familial hypercholesterolemia (FH) is one of the major risk factor for the progression of atherosclerosis and coronary artery disease. This study focused on identifying the dysregulated molecular pathways and core genes that are differentially regulated in FH and to identify the possible genetic factors and potential underlying mechanisms that increase the risk to atherosclerosis in patients with FH. Methods: The Affymetrix microarray dataset (GSE13985) from the GEO database and the GEO2R statistical tool were used to identify the differentially expressed genes (DEGs) from the white blood cells (WBCs) of five heterozygous FH patients and five healthy controls. The interaction between the DEGs was identified by applying the STRING tool and visualized using Cytoscape software. MCODE was used to determine the gene cluster in the interactive networks. The identified DEGs were subjected to the DAVID v6.8 webserver and ClueGo/CluePedia for functional annotation, such as gene ontology (GO) and enriched molecular pathway analysis of DEGs. Results: We investigated the top 250 significant DEGs (p-value < 0.05; fold two change ≥ 1 or ≤ -1). The GO analysis of DEGs with significant differences revealed that they are involved in critical biological processes and molecular pathways, such as myeloid cell differentiation, peptidyl-lysine modification, signaling pathway of MyD88-dependent Toll-like receptor, and cell-cell adhesion. The analysis of enriched KEGG pathways revealed the association of the DEGs in ubiquitin-mediated proteolysis and cardiac muscle contraction. The genes involved in the molecular pathways were shown to be differentially regulated by either activating or inhibiting the genes that are essential for the canonical signaling pathways. Our study identified seven core genes (UQCR11, UBE2N, ADD1, TLN1, IRAK3, LY96, and MAP3K1) that are strongly linked to FH and lead to a higher risk of atherosclerosis. Conclusion: We identified seven core genes that represent potential molecular biomarkers for the diagnosis of atherosclerosis and might serve as a platform for developing therapeutics against both FH and atherosclerosis. However, functional studies are further needed to validate their role in the pathogenesis of FH and atherosclerosis.

Therapeutic Options for Homozygous Familial Hypercholesterolemia: The Role of Lomitapide

Background:

Lomitapide (Juxtapid® in US and Lojuxta® in Europe) is the first developed inhibitor of the Microsomal Triglyceride Transfer Protein (MTP) approved as a novel drug for the management of Homozygous Familial Hypercholesterolemia (HoFH). It acts by binding directly and selectively to MTP thus decreasing the assembly and secretion of the apo-B containing lipoproteins both in the liver and in the intestine.

Aims:

The present review aims at summarizing the recent knowledge on lomitapide in the management of HoFH.

Results:

The efficacy and safety of lomitapide have been evaluated in several trials and it has been shown a reduction of the plasma levels of Low-Density Lipoprotein Cholesterol (LDL-C) by an average of more than 50%. Although the most common side effects are gastrointestinal and liver events, lomitapide presents generally with a good tolerability and satisfactory patients compliance. Recently, in Europe, to evaluate the long-term safety and efficacy of lomitapide, the LOWER registry (ClinicalTrials.gov Identifier: NCT02135705) has been established in order to acquire informations on HoFH lomitapidetreated patients from “real life” clinical practice.

:

Furthermore, the observation that lomitapide decreases triglyceride levels may be considered for patients affected by severe forms of hypertriglyceridemia who undergo recurrent episodes of pancreatitis and are poor responders to conventional treatment.

Conclusion:

Lomitapide represents an innovative and efficacious drug for the treatment of HoFH. Longterm safety data, treatment of pediatric and pregnant HoFH patients and management of severe hypertriglyceridemia still require further investigations.

Identifying patients with familial hypercholesterolemia using data mining methods in the Northern Great Plain region of Hungary

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is one of the most frequent diseases with monogenic inheritance. Previous data indicated that the heterozygous form occurred in 1:250 people. Based on these reports, around 36,000-40,000 people are estimated to have FH in Hungary, however, there are no exact data about the frequency of the disease in our country. Therefore, we initiated a cooperation with a clinical site partner company that provides modern data mining methods, on the basis of medical and statistical records, and we applied them to two major hospitals in the Northern Great Plain region of Hungary to find patients with a possible diagnosis of FH.

METHODS

Medical records of 1,342,124 patients were included in our study. From the mined data, we calculated Dutch Lipid Clinic Network (DLCN) scores for each patient and grouped them according to the criteria to assess the likelihood of the diagnosis of FH. We also calculated the mean lipid levels before the diagnosis and treatment.

RESULTS

We identified 225 patients with a DLCN score of 6-8 (mean total cholesterol: 9.38 ± 3.0 mmol/L, mean LDL-C: 7.61 ± 2.4 mmol/L), and 11,706 patients with a DLCN score of 3-5 (mean total cholesterol: 7.34 ± 1.2 mmol/L, mean LDL-C: 5.26 ± 0.8 mmol/L).

CONCLUSIONS

The analysis of more regional and country-wide data and more frequent measurements of total cholesterol and LDL-C levels would increase the number of FH cases discovered. Data mining seems to be ideal for filtering and screening of FH in Hungary.

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.

Endoplasmic reticulum quality control of LDLR variants associated with familial hypercholesterolemia

Loss-of-function mutations in the low-density lipoprotein receptor (LDLR) gene can cause familial hypercholesterolemia (FH), but detailed functional evidence for pathogenicity is limited to a few reported mutations. Here, we investigated the cellular pathogenic mechanisms of three mutations in LDLR causing FH, which are structurally identical to pathogenic mutations in the very low-density lipoprotein receptor (VLDLR). Similar to the VLDLR mutants, LDLR mutants D482H and C667F were found to be localized to the ER, while D445E, which is a conserved amino acid change, did not affect the trafficking of the receptor to the plasma membrane, as confirmed by the N-glycosylation profile. Although the ER-retained mutant proteins were soluble, induction of ER stress was observed as indicated by spliced X-box binding protein-1 (XBP-1) mRNA levels. The mutants were found to associate with ER quality control components, and their stability was enhanced by inhibitors of proteasome. Our results contribute to the growing list of transport-deficient class II LDLR variants leading to FH and provide evidence for the involvement of endoplasmic reticulum-associated degradation in their stability.

Healthcare Utilization and Patients' Perspectives After Receiving a Positive Genetic Test for Familial Hypercholesterolemia

BACKGROUND

The MyCode Community Health Initiative (MyCode) is returning actionable results from whole exome sequencing. Familial hypercholesterolemia (FH) is an inherited condition characterized by premature cardiovascular disease.

METHODS

We used multiple methods to assess care in 28 MyCode participants who received FH results. Chart reviews were conducted on 23 individuals in the sample and 7 individuals participated semistructured interviews.

RESULTS

Chart reviews for 23 individuals with a Geisinger primary care provider found that 4 individuals (17% of 23) were at LDL-C (low-density lipoprotein cholesterol) goal (of either LDL-C <100 mg/dL for primary prevention and LDL-C <70 mg/dL for secondary prevention) and 17 individuals (74% of 23) were prescribed lipid-lowering therapy before genetic result disclosure. After disclosure of the genetic test result, 5 individuals (22% of 23) met their LDL-C goal and 18 individuals (78% of 23) were prescribed lipid-lowering therapy. Follow-up care about this result was not documented for 4 individuals (17% of 23). Changes to intensity of medication management were made for 8 individuals (47% of 17 individuals previously prescribed lipid-lowering therapy). Interviewed individuals (n=7) were not surprised by their result as all knew they had high cholesterol; however, individuals did not seem to discern FH as a separate condition from their high cholesterol.

CONCLUSIONS

Among individuals receiving genetic diagnosis of FH, >25% had no changes to lipid-lowering therapy, despite not being at LDL-C goal and learning their high cholesterol is related to a genetic condition requiring more aggressive treatment. Individuals and clinicians may have an inadequate understanding of FH as a distinct condition requiring enhanced medical management.

DNA Methylation in Epidermal Differentiation, Aging, and Cancer

The formation and maintenance of the epidermis depend on epidermal stem cell differentiation and must be tightly regulated. Epigenetic mechanisms such as DNA methylation allow the precise gene expression cascade needed during cellular differentiation. However, these mechanisms become deregulated during aging and tumorigenesis, where cellular function and identity become compromised. Here we provide a review of this rapidly developing field. We discuss recent discoveries related to epidermal homeostasis, aging, and cancer, including the functional role of DNA methyltransferases, the methylation clock, and the determination of tumor cells-of-origin. Finally, we focus on future advances, greatly influenced by single-cell sequencing technologies.

An interspecies study of lipid profiles and atherosclerosis in familial hypercholesterolemia animal models with low-density lipoprotein receptor deficiency

Small rodents, especially mice and rats, have been widely used in atherosclerosis studies even though humans exhibit completely different lipoprotein metabolism and atherosclerotic characteristics. Until recently, various rodent models of human familial hypercholesterolemia (FH) have been created, including mice, rats, and golden Syrian hamsters. Although hamsters reportedly possess metabolic features similar to humans, there is no systematic characterization of the properties of circulating lipids and atherosclerotic lesions in these rodent models. We used three FH animal species (mice, rats, and hamsters) with low-density lipoprotein receptor (Ldlr) deficiency to fully assess lipoprotein metabolism and atherosclerotic characteristics. Compared to chow diet-fed mice and rats, Ldlr knockout (KO) hamsters showed increased cholesterols in LDL fractions similar to human FH patients. Upon 12-week high-cholesterol/high-fat diet feeding, both heterozygous and homozygous Ldlr KO hamsters displayed hyperlipidemic phenotypes, whereas only homozygous Ldlr KO mice and rats showed only moderate increases in plasma lipid levels. Moreover, rats were resistant to diet-induced atherosclerosis compared to mice, and hamsters showed more atherosclerotic lesions in the aortas and coronary arteries. Further morphological study revealed that only hamsters developed atherosclerosis in the abdominal segments, which is highly similar to FH patients. This unique animal model will provide insight into the translational study of human atherosclerosis and could be useful for developing novel treatments for FH patients.

The immune functions of PCSK9: Local and systemic perspectives

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low-density lipoprotein receptor (LDLR) to trigger endocytosis and lysosome degradation in hepatocytes, regulating intracellular and plasma cholesterol levels. The discovery of PCSK9 has provided a new target for the management of hypercholesterolemia and cardiovascular risk reduction. There is emerging evidence that shows that PCSK9 may influence the activity of various cell types through either LDLR-dependent or LDLR-independent mechanisms. Changes in the circulating PCSK9 levels have been observed during infection and proinflammatory conditions. Furthermore, PCSK9 as a secreted protein has both local and systemic effects on cellular function. In this review, we summarize the roles of PCSK9 in inflammation.

Familial Hypercholesterolemia: New Horizons for Diagnosis and Effective Management

Familial hypercholesterolemia (FH) is a common genetic cause of premature cardiovascular disease (CVD). The reported prevalence rates for both heterozygous FH (HeFH) and homozygous FH (HoFH) vary significantly, and this can be attributed, at least in part, to the variable diagnostic criteria used across different populations. Due to lack of consistent data, new global registries and unified guidelines are being formed, which are expected to advance current knowledge and improve the care of FH patients. This review presents a comprehensive overview of the pathophysiology, epidemiology, manifestations, and pharmacological treatment of FH, whilst summarizing the up-to-date relevant recommendations and guidelines. Ongoing research in FH seems promising and novel therapies are expected to be introduced in clinical practice in order to compliment or even substitute current treatment options, aiming for better lipid-lowering effects, fewer side effects, and improved clinical outcomes.

Genetic analysis in a compound heterozygote family with familial hypercholesterolemia

Homozygous familial hypercholesterolemia (FH) is rare, with an incidence of ~one in a million and commonly presents with a genetic mutation. The genetic variations of families with FH were clinically analyzed to investigate the association between the phenotype and genotype of patients. Direct sequencing was conducted for the proband and her parents to detect mutations in the fragment of 18 exons of the low‑density lipoprotein receptor (LDLR) and apolipoprotein B100 Q3500R in the peripheral blood genomic DNA. The gene sequences were compared with normal ones to find mutations using GenBank. The QX200 Droplet Digital PCR system was used to detect target DNA copy number variations of the proband and her parents. The functional alterations resulting from the novel mutations were verified by quantitative polymerase chain reaction, western blotting and flow cytometric analyses. The lipid levels of the proband and her parents were all elevated. Genetic testing results indicated that the proband and her mother had a novel heterozygous missense mutation (C377G, 28893T>G) in exon 8 of the LDLR gene, whereas the proband and her father had LDLR gene DNA fragment deletions in exon 18. Clinically, the proband was of a compound heterozygous genotype and her parents were of the simple heterozygous genotype. Furthermore, both mutations led to impaired expression and LDL binding and internalization function of LDLR in vitro. The proband's genotype was confirmed to be compound heterozygous FH, leading to clinical manifestations in line with the homozygous FH phenotype. The phenotype is highly associated with the genotype in this type of compound heterozygous FH.

Screening of LDLR and APOB gene mutations in Mexican patients with homozygous familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant disorder that causes accumulation of serum low-density lipoprotein cholesterol and premature cardiovascular disease. It is mainly related to mutations in the LDLR gene. Homozygous FH (HoFH) patients have the most severe form of the disease accounting for a worldwide prevalence of 1:1,000,000. In Mexico, at least 5 cases of HoFH have been reported.

OBJECTIVE

The aim of this study was to describe the clinical, biochemical, and molecular data observed in patients with HoFH phenotype.

METHODS

We included 13 patients, belonging to 11 families, with clinical and biochemical diagnoses suggestive of HoFH. Molecular analyses of the LDLR and APOB genes were performed by means of polymerase chain reaction followed by Sanger sequencing.

RESULTS

The causal mutation of HoFH was found in 8 of 11 unrelated patients. Excepting 1, all were true homozygotes. Six different variants in LDLR were identified: c.-139delCTCCCCCTGC, p.Glu140Lys, p.Asp360His, p.Asn405Lys, p.Ala755Glyfs*7, and p.Leu759Serfs*6. Of these, p.Asp360His and p.Asn405Lys were detected for the first time in Mexico; p.Leu759Serfs*6 showed to be the most frequent (43.7% of the alleles 7/16), and c.-139delCTCCCCCTGC is a new variant located in the promoter region.

CONCLUSIONS

This work increases knowledge of biochemical and genetic features in Mexican patients with HoFH. A novel mutation in the LDLR gene promoter was detected: c.-139delCTCCCCCTGC, which possibly inhibits its expression.