Xanthomas Can Be Misdiagnosed and Mistreated in Homozygous Familial Hypercholesterolemia Patients: A Call for Increased Awareness Among Dermatologists and Health Care Practitioners

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.

What Causes Premature Coronary Artery Disease?

PURPOSE OF REVIEW

This review provides an overview of genetic and non-genetic causes of premature coronary artery disease (pCAD).

RECENT FINDINGS

pCAD refers to coronary artery disease (CAD) occurring before the age of 65 years in women and 55 years in men. Both genetic and non-genetic risk factors may contribute to the onset of pCAD. Recent advances in the genetic epidemiology of pCAD have revealed the importance of both monogenic and polygenic contributions to pCAD. Familial hypercholesterolemia (FH) is the most common monogenic disorder associated with atherosclerotic pCAD. However, clinical overreliance on monogenic genes can result in overlooked genetic causes of pCAD, especially polygenic contributions. Non-genetic factors, notably smoking and drug use, are also important contributors to pCAD. Cigarette smoking has been observed in 25.5% of pCAD patients relative to 12.2% of non-pCAD patients. Finally, myocardial infarction (MI) associated with spontaneous coronary artery dissection (SCAD) may result in similar clinical presentations as atherosclerotic pCAD. Recognizing the genetic and non-genetic causes underlying pCAD is important for appropriate prevention and treatment. Despite recent progress, pCAD remains incompletely understood, highlighting the need for both awareness and research.

Modern approaches to the management of homozygous familial hypercholesterolemia in the Middle East and North Africa

Homozygous familial hypercholesterolaemia (HoFH) is a severe form of FH in which inheritance of two defective or null mutations in genes associated with metabolism of low-density lipoprotein cholesterol (LDL-C) results in extremely high LDL-C, premature atherosclerotic cardiovascular disease (ASCVD) and mortality. Treatment of HoFH comprises a multi-modal approach of statins, ezetimibe, lipoprotein apheresis; and inhibitors of proprotein convertase subtilisin/kexin type, angiopoietin-like protein 3 (ANGPTL3) and microsomal triglyceride transfer protein. These treatments are generally costly, and patients also often require treatment for ASCVD consequent to HoFH. Therefore, in the interests of both economics and preservation of life, disease prevention via genetic screening and counselling is rapidly becoming a key element in the overall management of HoFH. Guidelines are available to assist diagnosis and treatment of HoFH; however, while advancements have been made in the management of the disease, there has been little systematic attention paid to prevention. Additionally, the Middle East/North Africa (MENA) region has a higher prevalence of HoFH than most other regions - chiefly due to consanguinity. This has led to the establishment of regional lipid clinics and awareness programs that have thrown education and awareness of HoFH into sharp focus. Incorporation of principles of prevention, education, awareness, and data from real-world use of existing therapeutics will significantly enhance the effectiveness of future guidelines for the management of HoFH, particularly in the MENA region.

Novel LDLR variants affecting low density lipoprotein metabolism identified in familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant disease of lipid metabolism mainly caused by mutations in the low-density lipoprotein receptor (LDLR) gene. Genetic detection of patients with FH help with precise diagnosis and treatment, thus reducing the risk of coronary heart disease (CHD) and other related diseases. The study aimed to identify the causative gene mutations in a Chinese FH family and reveal the pathogenicity and the mechanism of these mutations.

METHODS AND RESULTS

Whole exome sequencing was performed in a patient with severe lipid metabolism dysfunction seeking fertility guidance from a Chinese FH family. Two LDLR variants c.1875 C > G (p.N625K; novel variant) and c.1448G > A (p.W483*) were identified in the family. Wildtype and mutant LDLR constructs were established by the site-direct mutagenesis technique. Functional studies were carried out by cell transfection to evaluate the impact of detected variants on LDLR activity. The two variants were proven to affect LDL uptake and binding, resulting in cholesterol clearance reduction to different degrees. According to The American College of Medical Genetics and Genomics (ACMG) Standards and Guidelines, the W483* variant was classified as "Pathogenic", while the N625K variant as "VUS".

CONCLUSIONS

Our results provide novel experimental evidence of functional alteration by LDLR variants identified in our study and expand the mutational spectrum of LDLR mutation induced FH.

Identification and functional characterization of two rare LDLR stop gain variants (p.C231* and p.R744*) in Saudi familial hypercholesterolemia patients

BACKGROUND

Familial hypercholesterolemia (FH) is a globally underdiagnosed inherited metabolic disorder. Owing to limited published data from Arab world, this study was conducted with the aim of identifying the genetic and molecular basis of FH in highly consanguineous Saudi population.

METHODS

We performed clinical screening, biochemical profiling, whole exome sequencing and variant segregation analysis of two Saudi FH families. Additionally, 500 normolipic individuals were screened to ensure the absence of FH variant in general Saudi population. Functional characterization of FH variants on secondary structure characteristics of RNA and protein molecules was performed using different bioinformatics modelling approaches.

RESULTS

WES analysis identified two independent rare LDLR gene stop gain variants (p.C231* and p.R744*) consistent to the clinical presentation of FH patients from two different families. RNAfold analysis has shown that both variants were predicted to disturb the free energy dynamics of LDLR mRNA molecule and destabilize its folding pattern and function. PSIPRED based structural modelling analysis has suggested that both variants bring drastic changes disturbing the secondary structural elements of LDLR molecule. The p.C231* and p.R744* variants are responsible for partial or no protein product, thus they are class 1 variants causing loss of function (LoF) LDLR variants.

CONCLUSIONS

This study highlights the effectiveness of the WES, sanger sequencing, and computational analysis in expanding FH variant spectrum in culturally distinct populations like Saudi Arabia. Genetic testing of FH patients is very essential in better clinical diagnosis, screening, treatment, and management and prevention of cardiovascular disease burden in the society.

Novel LDLR Variant in Familial Hypercholesterolemia: NGS-Based Identification, In Silico Characterization, and Pharmacogenetic Insights

BACKGROUND

Familial Hypercholesterolemia (FH) is a hereditary condition that causes a rise in blood cholesterol throughout a person's life. FH can result in myocardial infarction and even sudden death if not treated. FH is thought to be caused mainly by variants in the gene for the low-density lipoprotein receptor (LDLR). This study aimed to investigate the genetic variants in FH patients, verify their pathogenicity, and comprehend the relationships between genotype and phenotype. Also, review studies assessed the relationship between the LDLR null variants and the reaction to lipid-lowering therapy.

METHODS

The study utilised high-throughput next-generation sequencing for genetic screening of FH-associated genes and capillary sequencing for cascade screening. Furthermore, bioinformatic analysis was employed to describe the pathogenic effects of the revealed novel variant on the structural features of the corresponding RNA molecule.

RESULTS

We studied the clinical signs of hypercholesterolemia in a Saudi family with three generations of FH. We discovered a novel frameshift variant (c.666_670dup, p.(Asp224Alafs*43) in the LDLR and a known single nucleotide variant (c.9835A > G, p.(Ser3279Gly) in the APOB gene. It is thought that the LDLR variant causes a protein to be prematurely truncated, likely through nonsense-mediated protein decay. The LDLR variant is strongly predicted to be pathogenic in accordance with ACMG guidelines and co-segregated with the FH clinical characteristics of the family. This LDLR variant exhibited severe clinical FH phenotypes and was restricted to the LDLR protein's ligand-binding domain. According to computational functional characterization, this LDLR variant was predicted to change the free energy dynamics of the RNA molecule, thereby affecting its stability. This frameshift variant is thought to eliminate important functional domains in LDLR that are required for receptor recycling and LDL particle binding. We provide insight into how FH patients with a null variant in the LDLR gene respond to lipid-lowering therapy.

CONCLUSIONS

The findings expand the range of FH variants and assist coronary artery disease preventive efforts by improving diagnosis, understanding the genotype-phenotype relationship, prognosis, and personalised therapy for patients with FH.

Identification of Novel and Known LDLR Variants Triggering Severe Familial Hypercholesterolemia in Saudi Families

BACKGROUND

Familial hypercholesterolemia (FH) is a common illness mainly caused by variants occurring in the low-density lipoprotein receptor (LDLR) gene. FH is a leading cause of coronary artery disease.

OBJECTIVE

This study aims to determine genetic defect(s) in homozygous and heterozygous FH index patients and their first-degree blood relatives and understand the genotype-phenotype correlation.

METHODS

This study employed the genetic screening of FH-related genes by next-generation sequencing and cascade screening by capillary sequencing.

RESULTS

We identified the presence of a novel frameshift variant [c.335_336insCGAG, p.(F114Rfs*17)] and three known missense variants [c.622G>A, p.(E208K)], [c.1474G>A, p.(D492N)], [c.1429G>A, p.(D477N)] in the LDLR gene of four unrelated Saudi families with FH. In proband 1, a nonsense variant c.1421C>G, p.(S474*) was also detected at exon 9 of the lipoprotein lipase gene. The segregation arrangement of the identified variants corresponded with the clinical characteristics. In this study, all the detected variants were confined in the ligand-binding domain and epidermal growth factor (EGF)-precursor homology domain of the LDLR protein, which portrayed severe clinical phenotypes of FH. Moreover, these LDLR variants were in a highly conserved residue of the proteins.

CONCLUSION

In addition to the finding of the novel variant in the LDLR gene that extends the spectrum of variants causing FH, the results of this study also support the need for diagnostic screening and cascade genetic testing of this high-risk condition and to understand the genotype-phenotype correlation, which could lead to better prevention of coronary artery disease.

Recent Advances on Familial Hypercholesterolemia in Children and Adolescents

Familial hypercholesterolemia is a common autosomal hereditary disorder characterized by elevated concentrations of low-density lipoprotein cholesterol and the development of premature atherosclerosis and cardiovascular disease. Early diagnosis, as well as prompt and aggressive treatment, are fundamental steps to prevent cardiovascular complications and a high rate of premature mortality in children and adolescents. Clinics and genetics are the two main aspects on which diagnosis is based. Widespread screening programs are a respectable option for the early detection of familial hypercholesterolemia. Different types of screening have been proposed so far; however, the optimal screening program has not yet been found. The treatment approach for both heterozygous and homozygous familial hypercholesterolemia in the pediatric population is multidisciplinary, including lifestyle modifications, standard lipid-lowering medications, and novel pharmacological agents. The latter show promising results, especially for patients who experience intolerance to other treatment or present with more severe conditions. Our purpose is to focus on the importance of the early detection of familial hypercholesterolemia, and to highlight the best therapeutic strategies, including the recent approaches based on current clinical evidence, that need to be adopted from the earliest stages of life.

Familial Hypercholesterolemia in the Arabian Gulf Region: Clinical results of the Gulf FH Registry

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a common autosomal dominant disorder that can result in premature atherosclerotic cardiovascular disease (ASCVD). Limited data are available worldwide about the prevalence and management of FH. Here, we aimed to estimate the prevalence and management of patients with FH in five Arabian Gulf countries (Saudi Arabia, Oman, United Arab Emirates, Kuwait, and Bahrain).

METHODS

The multicentre, multinational Gulf FH registry included adults (≥18 years old) recruited from outpatient clinics in 14 tertiary-care centres across five Arabian Gulf countries over the last five years. The Gulf FH registry had four phases: 1- screening, 2- classification based on the Dutch Lipid Clinic Network, 3- genetic testing, and 4- follow-up.

RESULTS

Among 34,366 screened patient records, 3713 patients had suspected FH (mean age: 49±15 years; 52% women) and 306 patients had definite or probable FH. Thus, the estimated FH prevalence was 0.9% (1:112). Treatments included high-intensity statin therapy (34%), ezetimibe (10%), and proprotein convertase subtilisin/kexin type 9 inhibitors (0.4%). Targets for low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol were achieved by 12% and 30%, respectively, of patients at high ASCVD risk, and by 3% and 6%, respectively, of patients at very high ASCVD risk (p <0.001; for both comparisons).

CONCLUSIONS

This snap-shot study was the first to show the high estimated prevalence of FH in the Arabian Gulf region (about 3-fold the estimated prevalence worldwide), and is a "call-to-action" for further confirmation in future population studies. The small proportions of patients that achieved target LDL-C values implied that health care policies need to implement nation-wide screening, raise FH awareness, and improve management strategies for FH.

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.