Sudden death in a 4-year-old boy: a near-complete occlusion of the coronary artery caused by an aggressive low-density lipoprotein receptor mutation (W556R) in homozygous familial hypercholesterolemia

Acute Coronary Syndrome in a 9-Year-Old Girl With Homozygous Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a prevalent and underrecognized disorder. A young girl with previously undiagnosed homozygous FH presented with acute coronary syndrome. Severe coronary ostial stenosis and severe supravalvular aortic stenosis from atheromatous plaque was discovered. This case highlights the importance of screening and timely diagnosis of FH.

Reproductive Carrier Screening: Identifying Families at Risk for Familial Hypercholesterolemia in the United States

BACKGROUND

Familial hypercholesterolemia is a treatable genetic condition but remains underdiagnosed. We reviewed the frequency of pathogenic or likely pathogenic (P/LP) variants in the LDLR gene in female individuals receiving reproductive carrier screening.

METHODS

This retrospective observational study included samples from female patients (aged 18-55 years) receiving a 274-gene carrier screening panel from January 2020 to September 2022. LDLR exons and their 10 base pair flanking regions were sequenced. Carrier frequency for P/LP variants was calculated for the entire population and by race/ethnicity. The most common variants and their likely functional effects were evaluated.

RESULTS

A total of 91 637 tests were performed on women with race/ethnicity reported as Asian (8.8%), Black (6.1%), Hispanic (8.5%), White (29.0%), multiple or other (15.0%), and missing (33.0%). Median age was 32.8 years with 83 728 (91%) <40 years. P/LP LDLR variants were identified in 283 samples (1 in 324). No patients were identified with >1 P/LP variant. LDLR carrier frequency was higher in Asian (1 in 191 [95% CI, 1 in 142-258]) compared with White (1 in 417 [95% CI, 1 in 326-533]; P<0.001) or Black groups (1 in 508 [95% CI, 1 in 284-910]; P=0.004). The most common variants differed between populations. Of all variants, at least 25.0% were predicted as null variants.

CONCLUSIONS

P/LP variants in LDLR are common. Expanding the use of reproductive carrier screening to include genes associated with FH presents another opportunity to identify people predisposed to cardiovascular disease.

Diet and Lipid-Lowering Nutraceuticals in Pediatric Patients with Familial Hypercholesterolemia

Familial hypercholesterolemia is a genetically determined disease characterized by elevated plasma total and LDL cholesterol levels from the very first years of life, leading to early atherosclerosis. Nutritional intervention is the first-line treatment, complemented with nutraceuticals and drug therapy when necessary. Nutraceuticals with a lipid-lowering effect have been extensively studied in the past few decades, and have been recently included in international guidelines as a complement to nutritional and pharmacological treatment in subjects with dyslipidemia. In this review, we explore current nutritional interventions for dyslipidemia in childhood, with a specific focus on the main nutraceuticals studied for treating severe dyslipidemia in pediatric patients. Additionally, we briefly describe their primary mechanisms of action and highlight the advantages and risks associated with the use of lipid-lowering nutraceuticals in childhood.

[Advantages of Universal Early Childhood Screening for Familial Hypercholesterolaemia in Germany]

Hintergrund Kardiovaskuläre Ereignisse sind die wichtigste Mortalitätsursache in der westlichen Welt. Die familiäre Hypercholesterinämie (FH) zeichnet sich durch erhöhte low-density Lipoprotein-Cholesterin- und Gesamtcholesterin-Spiegel im peripheren Blut aus. Die FH beruht zumeist auf einer genetischen Veränderung im LDL-Rezeptorgen und gehört zu den häufigsten monogenen Erkrankungen. Bei der homozygoten Form ist die Mortalität aufgrund kardiovaskulärer Ereignisse im Kindes- und Jugendalter extrem hoch. Auch die heterozygote Form der FH führt unbehandelt früh zu kardiovaskulären Ereignissen und sollte frühzeitig diagnostiziert und behandelt werden, um eine Atherosklerose zu vermeiden. Die präventive und sichere Anwendung einer medikamentösen Lipidsenkung konnte für Kinder gezeigt werden.

Methode Literatursuche in Cochrane library, Medline, NCBI databases.

Ergebnisse Anders als in europäischen Nachbarländern wurde in Deutschland im Kindesalter kein universelles Screening auf diese häufige Erkrankung etabliert, obwohl dies in den Leitlinien gefordert wird. In der vorliegenden Arbeit wird die Literatur untersucht hinsichtlich der Kausalität der Erkrankung, der Therapie im Kindesalter sowie hinsichtlich des Zutreffens klassischer und modifizierter Kriterien für das Durchführen eines vorgeschlagenen universellen FH-Screenings zum 5. Geburtstag mit anschließendem reversen Kaskadenscreening bei Verwandten.

Schlussfolgerung Die Autoren plädieren für die Einführung eines universellen FH-Screenings in Deutschland zur Vorsorgeuntersuchung U9 mit 5 Jahren. Eine Analyse anhand des Goldstandards klassischer Kriterien nach Wilson und Jungner sowie anhand im zeitlichen Kontext angepasster Kriterien zeigt die Vorteile eines universellen frühkindlichen FH-Screening. Dieses kann präventiv das kardiovaskuläre Risiko absenken, das Fortschreiten der Atherosklerose verlangsamen und zu niedrigeren Inzidenzen von Schlaganfall und Herzinfarkt im Erwachsenenalter beitragen. Neben den diagnostizierten FH-Kindern können auch deren betroffene Verwandte erkannt werden.

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Vascular access for lipid apheresis: a challenge in young children with homozygous familial hypercholesterolemia

Background

Homozygous familial hypercholesterolemia (hoFH) is a rare genetic disorder leading to extremely increased LDL-cholesterol (LDL-C), resulting in high cardiovascular risk in early childhood. Lipid apheresis (LA) is an effective treatment and should be started as early as possible to prevent premature cardiovascular events. As peripheral punctures in children can be challenging due to small vessels and anxiety, this study aimed to evaluate feasibility and safety of central venous catheters (CVCs) as vascular access for LA in young children with hoFH.

Methods

Retrospective analysis (2016-2019) on four children with hoFH aged 3-5 years, performing weekly or biweekly LA with a CVC.

Results

LDL-C decreased by> 60%. In three children, the use of a permanent CVC for 698, 595, and 411 days, respectively, avoided difficult peripheral access, without the occurrence of occlusion or thrombosis. Unfortunately, one child had recurrent CVC-related infections and needed an arteriovenous fistula from the age of 5. Although the mean dwell time per catheter was 212 days, there were, as expected, severe side effects of early catheter infections with sepsis and accidental self-removal. Starting LA at an early age improved or stabilized carotid intima-media thickness (IMT) in three children. However, IMT did increase in one child caused by intolerance to peripheral punctures and LA interruption.

Conclusions

Permanent CVCs are a viable temporary access choice for LA in young children with hoFH until peripheral venipuncture is practicable. The risk of CVC-related infections needs to be taken into account.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03192-7.

Cohort Generation and Characterization of Patient-Specific Familial Hypercholesterolemia Induced Pluripotent Stem Cells

Homozygous familial hypercholesterolemia (hoFH) is a rare disorder caused primarily by pathological mutations in the low-density lipoprotein receptor (LDLR), which disrupts LDL-cholesterol (LDL-C) metabolism homeostasis. hoFH patients are at extremely high risk for cardiovascular disease and are resistant to standard therapies. LDLR knockout animals and in vitro cell models overexpressing different mutations have proved useful, but may not fully recapitulate human LDLR mutation biology. We and others have generated induced pluripotent stem cells (iPSC) from hoFH patient's fibroblasts and T cells and demonstrated their ability to recapitulate hoFH biology. In this study, we present the generation and characterization of a cohort of seven hoFH-iPSC lines derived from peripheral blood mononuclear cells (PBMC) collected from four homozygous and three compound heterozygous patients. The hoFH-iPSC cohort demonstrated a wide range of LDLR expression and LDL-C internalization in response to rosuvastatin that correlated with the predicted pathogenicity of the mutation. We were able to confirm that hoFH-iPSC cohort were pluripotent by differentiation toward all three germ layers and specifically to hepatocyte-like cells (HLC), the cell with primary LDL-C metabolic regulatory control, by expression of hepatocyte markers. hoFH patient PBMC-derived iPSC recapitulate the LDLR dysfunction of their specific mutation. They were capable of differentiating to HLC and could be useful for early developmental studies, pharmacology/toxicology, and potentially autologous cell therapy.

Homozygous Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an inherited disorder with retarded clearance of plasma LDL caused by mutations of the genes involved in the LDL receptor-mediated pathway and most of them exhibit autosomal dominant inheritance. Homozygotes of FH (HoFH) may have plasma LDL-C levels, which are at least twice as high as those of heterozygous FH (HeFH) and therefore four times higher than normal levels. Prevalence of HoFH had been estimated as 1 in 1,000,000 before but more recent genetic analysis surveys predict 1 in 170,000 to 300,000. Since LDL receptor activity is severely impaired, HoFH patients do not or very poorly respond to medications to enhance activity, such as statins, and have a poorer prognosis compared to HeFH. HoFH should therefore be clinically distinguished from HeFH. Thorough family studies and genetic analysis are recommended for their accurate diagnosis.

Fatal cardiovascular complications could develop even in the first decade of life for HoFH, so aggressive lipid-lowering therapy should be initiated as early as possible. Direct removal of plasma LDL by lipoprotein apheresis has been the principal measure for these patients. However, this treatment alone may not achieve stable LDL-C target levels and combination with drugs should be considered. The lipid-lowering effects of statins and PCSK9 inhibitors substantially vary depending on the remaining LDL receptor activity of individual patients. On the other hand, the action an MTP inhibitor is independent of LDL receptor activity, and it is effective in most HoFH cases.

This review summarizes the key clinical issues of HoFH as well as insurance coverage available under the Japanese public healthcare system.

Lipid Screening, Action, and Follow-up in Children and Adolescents

Purpose of Review

To create awareness for the devastating influence of high cholesterol in familial hypercholesterolaemia (FH) on vessel walls. Persons with high LDL-C and a known mutation associated with FH have a 22-fold increase in CVD compared with those with a normal LDL-C and no genetic mutation. If the awareness of the need to diagnose and treat this genetic disorder at an early stage increases, great atherosclerotic impact later in life could be avoided. Every minute a child with heterozygous FH is born somewhere in the world and every day a child with homozygous FH is born.

Recent Findings

Recent findings include effective therapy on statins from the age of 6 years, with already normalization of the intima-media thickness within 2 years. Newer types of drugs, with the same safety profile and perhaps even more effective, will become available in childhood in the near future. Open for discussion will be whom to treat and with what type of treatment. Next generation sequencing will perhaps easily select those in need of treatment and those at risk of adverse effects.

Summary

At the end of this review, statements and recommendations for children and adolescents with heterozygous FH are listed.

Multimodal lipid-lowering treatment in pediatric patients with homozygous familial hypercholesterolemia-target attainment requires further increase of intensity

BACKGROUND

Familial hypercholesterolemia (FH) causes premature cardiovascular disease (CVD). Lipoprotein apheresis (LA) is recommended as first-line lipid-lowering treatment (LLT) for homozygous (ho) FH.

METHODS

Efficacy of multimodal LLT including lifestyle counseling, drug treatment, and LA was analyzed in 17 pediatric hoFH or compound heterozygous (c-het) FH patients, who commenced chronic LA in Germany before the age of 18.

RESULTS

At time of diagnosis, mean low-density lipoprotein cholesterol (LDL-C) concentration was 19.6 mmol/l (756 mg/dl). Multimodal LLT resulted in 73% reduction of mean LDL-C concentration including a 62% contribution of LA. Only three children (18%) achieved mean LDL-C concentrations below the recommended pediatric target of 3.5 mmol/l (135 mg/dl). In 13 patients (76%) during chronic LA, neither cardiovascular events occurred nor was CVD progression detected clinically or by routine imaging techniques. In four patients (24%), cardiovascular events documented progression of CVD despite weekly LA, including one death due to coronary and cerebrovascular CVD which was not stabilized after commencing LA. Based on the mutational status, only 6 out of the 17 children were candidates for proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibition. Two already responded with further LDL-C decrease by 40%.

CONCLUSIONS

Next to drug therapy, regular LA is an essential component of LLT for approaching LDL-C targets in children with hoFH or c-hetFH, which was successful only in a minority of children. Progression of CVD morbidity and resulting mortality remain unresolved issues. Early and intensified multimodal LLT guided by risk factors beyond LDL-C concentration is needed to improve outcome.

Premature Coronary Artery Disease due to Homozygous Familial Hypercholesterolemia in a 12-Year-Old Girl

Background:

Homozygous familial hypercholesterolemia is a rare inherited metabolic disease caused by low-density lipoprotein receptor abnormality. Patients with homozygous familial hypercholesterolemia have an increased risk of cardiovascular complication that usually occurs in the first decade of life. Here, we report a 12-year-old girl with an unpredicted presentation for coronary artery disease and found to have homozygous familial hypercholesterolemia.

Case Report:

A 12-year-old girl was admitted to our unit with syncope. Chest X-ray showed bilateral diffuse pneumonic consolidation and mild cardiomegaly. We detected stable ST depression by electrocardiography. Echocardiography showed normal systolic functions. Troponin-1 levels were high (66 mcg/dL, upper limit: 0.04 mcg/dL). Influenza A virus DNA was detected by the respiratory viral panel. After her successful treatment for acute pneumonia and myocarditis due to Influenza A virus, her syncope attacks persisted. Marked ST elevation was observed during exercise electrocardiography. Coronary angiography showed severe occlusions in the coronary arteries. High serum levels of total cholesterol (756 mg/dL) and low-density lipoprotein-C (556 mg/dL) were noticed. She had no tendon xanthomas. Medical histories revealed that her family members were diagnosed with heterozygous familial hypercholesterolemia. A coronary bypass surgery was performed. Statin and ezetimibe treatments were started. We also planned lipid apheresis.

Conclusion:

Children with homozygous familial hypercholesterolemia may present with symptoms of premature coronary heart disease requiring a routine lipid test and careful anamnesis.

CRISPR Correction of a Homozygous Low-Density Lipoprotein Receptor Mutation in Familial Hypercholesterolemia Induced Pluripotent Stem Cells

Familial hypercholesterolemia (FH) is a hereditary disease primarily due to mutations in the low‐density lipoprotein receptor (LDLR) that lead to elevated cholesterol and premature development of cardiovascular disease. Homozygous FH patients (HoFH) with two dysfunctional LDLR alleles are not as successfully treated with standard hypercholesterol therapies, and more aggressive therapeutic approaches to control cholesterol levels must be considered. Liver transplant can resolve HoFH, and hepatocyte transplantation has shown promising results in animals and humans. However, demand for donated livers and high‐quality hepatocytes overwhelm the supply. Human pluripotent stem cells can differentiate to hepatocyte‐like cells (HLCs) with the potential for experimental and clinical use. To be of future clinical use as autologous cells, LDLR genetic mutations in derived FH‐HLCs need to be corrected. Genome editing technology clustered‐regularly‐interspaced‐short‐palindromic‐repeats/CRISPR‐associated 9 (CRISPR/Cas9) can repair pathologic genetic mutations in human induced pluripotent stem cells. Conclusion: We used CRISPR/Cas9 genome editing to permanently correct a 3‐base pair homozygous deletion in LDLR exon 4 of patient‐derived HoFH induced pluripotent stem cells. The genetic correction restored LDLR‐mediated endocytosis in FH‐HLCs and demonstrates the proof‐of‐principle that CRISPR‐mediated genetic modification can be successfully used to normalize HoFH cholesterol metabolism deficiency at the cellular level. (Hepatology Communications 2017;1:886–898)

Efficacy and Safety of Lomitapide in Hypercholesterolemia

BACKGROUND

Despite extensive use of statins, patients with hypercholesterolemia, especially homozygous familial hypercholesterolemia (HoFH), do not achieve recommended targets of low-density lipoprotein cholesterol (LDL-C). There is an urgent need for novel options that could reduce proatherogenic lipoprotein cholesterol levels. Lomitapide, a microsomal triglyceride transport protein (MTP) inhibitor, was approved three years ago as an orphan drug for the treatment of patients with HoFH.

OBJECTIVE

Our aim was to systematically evaluate the efficacy and safety of lomitapide and to provide guidance for clinicians.

METHODS

We searched the PubMed, Embase, and Cochrane library databases and ClinicalTrials.gov to identify valid studies published before 31 October 2016 that included lomitapide-treated patients who did or did not undergo lipid-lowering therapy. We assessed the quality of different studies. Data were extracted and evaluated for quality by two reviewers.

RESULTS

Studies reporting lomitapide therapy included one randomized controlled trial, three single-arm studies, and five case reports. In patients with HoFH, lomitapide reduced levels of LDL-C, total cholesterol, apolipoprotein B, and triglycerides with or without other lipid-lowering therapy, including apheresis. In non-HoFH patients with moderate hypercholesterolemia and hypertriglyceridemia, lomitapide also showed favorable effects on changes in LDL-C and triglycerides. However, both HoFH and non-HoFH patients experienced a reduction in high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-1 (ApoA-1). The most common adverse event was gastrointestinal disorder, and others included liver transaminase elevation and hepatic fat accumulation. Long-term use of lomitapide was associated with an increased risk of progressing to steatohepatitis and fibrosis.

CONCLUSIONS

Lomitapide improved most lipid parameters but not HDL-C or ApoA-1 in patients with HoFH and in non-HoFH patients, and gastrointestinal disorders were the most common adverse event. The possible benefits of lomitapide should be further evaluated and viewed against its possible long-term side effects.

Efficacy of Lomitapide in the Treatment of Familial Homozygous Hypercholesterolemia: Results of a Real-World Clinical Experience in Italy

INTRODUCTION

Homozygous familial hypercholesterolaemia (HoFH) is a rare form of inherited dyslipidemia resistant to conventional cholesterol-lowering medications so that lipoprotein apheresis (LA) is usually required. Lomitapide has been approved for the treatment of HoFH. The aim of this study was to evaluate the benefits of lomitapide in HoFH patients followed with the usual clinical care.

METHODS

Clinical and biochemical data were retrospectively collected in 15 HoFH patients (10 with mutations in the LDLR gene and 5 in the LDLRAP1 gene) treated for at least 6 months with lomitapide in addition to lipid-lowering therapies (LLT) in different Lipid Clinics across Italy.

RESULTS

The mean follow-up period was 32.3 ± 29.7 months. During background therapies, HoFH patients showed a mean LDL-C level of 426.0 ± 204.0 mg/dl. The addition of lomitapide at the average dosage of 19 mg/day lowered LDL-C levels by 68.2 ± 24.8%. At their last visit, 60% of patients showed LDL-C <100 mg/dl and 46.6% <70 mg/dl. During follow-up, 8 of 10 patients receiving LA (80%) stopped this treatment due to marked LDL-C reduction. A wide range (13-95%) of individual LDL-C reduction was observed, but this was not related to genotype. During follow-up, 53.3% of patients reported at least one episode of diarrhea, but none was referred as severe; none had liver transaminase >5× ULN or had to stop treatment due to side effects. A subset of patients was evaluated by liver ultrasound and fibroscan (n = 5) or nuclear magnetic resonance with spectroscopy (MRS) (n = 1) not showing clinical evidence of liver damage.

CONCLUSION

In this real-world experience, lomitapide was confirmed to be a very powerful cholesterol-lowering agent in HoFH showing a good safety profile.

Homozygous familial hypercholesterolemia: Summarized case reports

BACKGROUND AND AIMS

Homozygous familial hypercholesterolemia (hoFH) is a rare genetic disorder with potential severe atherosclerosis in the pediatric age.

METHODS

We report on 9 patients with hoFH, who had been diagnosed within the last 30 years and who were consequently treated with apheresis and drugs.

RESULTS

Two deaths occurred: one at age 36 years and the other at age four and a half years before effective treatment was commenced. All other patients are still in good clinical condition today, although four of them have proven aortic stenosis or arterial plaques.

CONCLUSIONS

Our case report highlights that adequate treatment should start as early as possible to delay the onset of clinical manifestations of atherosclerosis. It can be assumed that the introduction of new drugs can improve the outcome and possibly lengthen the life expectancy of patients affected by hoFH.

LDL-Cholesterol: Standards of Treatment 2016: A German Perspective

Decreasing low-density lipoprotein cholesterol (LDL-C) is one of the few established and proven principles for the prevention and treatment of atherosclerosis. The higher the individual cardiovascular risk, the higher the benefit of lipid-lowering pharmacotherapy. Therefore, treatment options are chosen based on a patient's total cardiovascular risk. The latter depends not only on the levels of LDL-C but also on the presence of cardiovascular disease (CVD) and on the number and severity of other risk factors. Current guidelines recommend the lowering of LDL-C to 115 mg/dl (3 mmol/l) in patients with low and moderate risk. The LDL-C treatment target is <100 mg/dl (2.6 mmol/l) for patients at high risk and <70 mg/dl (1.8 mmol/l) for patients at very high risk. Although lifestyle measures remain a fundamental part of treatment, many patients require drug therapy to achieve their LDL-C targets. Statins are the drugs of choice, with other options including ezetimibe and the newly available monoclonal antibodies against PCSK9 (proprotein convertase subtilisin/kexin type 9). In some cases, bile acid-binding sequestrants and fibrates can also be considered. Nicotinic acid is no longer available in Germany. PCSK9 antibodies decrease LDL-C about 50-60 % and are well tolerated. Their effects on clinical endpoints are being investigated in large randomized trials. The aim of the present review is to summarize the current guidelines and treatment options for hypercholesterolemia. Moreover, we provide an appraisal of PCSK9 antibodies and propose their use in selected patient populations, particularly in those at very high cardiovascular risk whose LDL-C levels under maximally tolerated lipid-lowering therapy are significantly over their treatment target.

Novel Therapies for Familial Hypercholesterolemia

OPINION STATEMENT

Both HeFH and HoFH require dietary and lifestyle modification. Pharmacotherapy of adult HeFH patients is largely driven by the American Heart Association (AHA) algorithm. A high-potency statin is started initially with a goal low-density lipoprotein cholesterol (LDL-C) reduction of >50 %. The LDL-C target is adjusted to <100 or <70 mg/dL in subjects with coronary artery disease (CAD) with ezetimibe being second line. If necessary, a third adjunctive therapy, such as a PSCK9 inhibitor (not yet approved in children) or bile acid-binding resin, can be added. Finally, LDL-C apheresis can be considered in patients with LDL-C >300 mg/dL (or >200 mg/dL with significant CAD, although now approved for LDL-C as low as 160 mg/dL with CAD). Due to the early, severe LDL-C elevation in HoFH patients, concerning natural history, rarity of the condition, and nuances of treatment, all HoFH patients should be treated at a pediatric or adult center with HoFH experience. LDL-C apheresis should be considered as early as 5 years of age. However, apheresis availability and tolerability is limited and pharmacotherapy is required. Generally, the AHA algorithm with reference to the European Atherosclerosis Society Consensus Panel recommendations is reasonable with all patients initiated on high-dose, high-potency statin, ezetimibe, and bile acid-binding resins. In most, additional LDL-C lowering is required with PCSK9 inhibitors and/or lomitapide or mipomersen. Liver transplantation can also be considered at experienced centers as a last resort.

Challenges in the Diagnosis and Treatment of Homozygous Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a rare, genetic disorder characterized by an absence or impairment of low-density lipoprotein receptor (LDLR) function resulting in significantly elevated low-density lipoprotein cholesterol (LDL-C) levels. The cholesterol exposure burden beginning in utero greatly increases the risk for atherosclerotic cardiovascular disease (ASCVD) and premature death. The genetic heterogeneity of HoFH results in a wide range of LDL-C levels among both untreated and treated patients. Diagnosis of HoFH should, therefore, be based on a comprehensive evaluation of clinical criteria and not exclusively LDL-C levels. As treatment goals, the European Atherosclerosis Society and International FH Foundation suggest target LDL-C levels of <100 mg/dL (<2.5 mmol/L) in adults or <70 mg/dL (<1.8 mmol/L) in adults with clinical coronary artery disease or diabetes. The National Lipid Association (NLA) recommends that LDL-C levels be reduced to <100 mg/dL (<2.5 mmol/L) or by at least ≥50 % from pretreatment levels. Conventional therapy combinations that lower atherogenic lipoproteins levels in the blood, such as statins, ezetimibe, bile acid sequestrants and niacin, as well as lipoprotein apheresis, are usually unable to reduce LDL-C levels to recommended targets. Two recently approved agents that reduce lipoprotein synthesis and secretion by the liver are lomitapide, a microsomal triglyceride transfer protein inhibitor, and mipomersen, an apolipoprotein B antisense oligonucleotide. The newly approved inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9), evolocumab, also shows promise for the management of FH. Because of the extremely high risk for ASCVD, HoFH patients should be identified early.

Cardiovascular risk stratification in familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a common autosomal-dominant disorder in most European countries. Patients with FH are characterised by a raised level of low-density lipoprotein cholesterol and a high risk of premature coronary heart disease (CHD). Currently there is no consensus regarding the clinical utility to predict future coronary events or testing for the presence of subclinical atherosclerotic disease in asymptomatic patients with FH. Family screening of patients with FH as recommended by the UK National Institute of Health and Care Excellence guideline would result in finding many young individuals with a diagnosis of FH who are clinically asymptomatic. The traditional CHD risk scores, that is, the Framingham score, are insufficient in risk prediction in this group of young individuals. In addition, a better understanding of the genetic aetiology of the FH phenotype and CHD risk in monogenic FH and polygenic hypercholesterolaemia is needed. Non-invasive imaging methods such as carotid intima-media thickness measurement might produce more reliable information in finding high-risk patients with FH. The potential market authorisation of novel therapeutic agents such as PCSK9 monoclonal inhibitors makes it essential to have a better screening programme to prioritise the candidates for treatment with the most severe form of FH and at higher risk of coronary events. The utility of new imaging techniques and new cardiovascular biomarkers remains to be determined in prospective trials.

The genetics and screening of familial hypercholesterolaemia

Familial Hypercholesterolaemia is an autosomal, dominant genetic disorder that leads to elevated blood cholesterol and a dramatically increased risk of atherosclerosis. It is perceived as a rare condition. However it affects 1 in 250 of the population globally, making it an important public health concern. In communities with founder effects, higher disease prevalences are observed.

We discuss the genetic basis of familial hypercholesterolaemia, examining the distribution of variants known to be associated with the condition across the exons of the genes LDLR, ApoB, PCSK9 and LDLRAP1. We also discuss screening programmes for familial hypercholesterolaemia and their cost-effectiveness. Diagnosis typically occurs using one of the Dutch Lipid Clinic Network (DCLN), Simon Broome Register (SBR) or Make Early Diagnosis to Prevent Early Death (MEDPED) criteria, each of which requires a different set of patient data. New cases can be identified by screening the family members of an index case that has been identified as a result of referral to a lipid clinic in a process called cascade screening. Alternatively, universal screening may be used whereby a population is systematically screened.

It is currently significantly more cost effective to identify familial hypercholesterolaemia cases through cascade screening than universal screening. However, the cost of sequencing patient DNA has fallen dramatically in recent years and if the rate of progress continues, this may change.

Familial hypercholesterolaemia in children and adolescents: gaining decades of life by optimizing detection and treatment

Familial hypercholesterolaemia (FH) is a common genetic cause of premature coronary heart disease (CHD). Globally, one baby is born with FH every minute. If diagnosed and treated early in childhood, individuals with FH can have normal life expectancy. This consensus paper aims to improve awareness of the need for early detection and management of FH children. Familial hypercholesterolaemia is diagnosed either on phenotypic criteria, i.e. an elevated low-density lipoprotein cholesterol (LDL-C) level plus a family history of elevated LDL-C, premature coronary artery disease and/or genetic diagnosis, or positive genetic testing. Childhood is the optimal period for discrimination between FH and non-FH using LDL-C screening. An LDL-C ≥5 mmol/L (190 mg/dL), or an LDL-C ≥4 mmol/L (160 mg/dL) with family history of premature CHD and/or high baseline cholesterol in one parent, make the phenotypic diagnosis. If a parent has a genetic defect, the LDL-C cut-off for the child is ≥3.5 mmol/L (130 mg/dL). We recommend cascade screening of families using a combined phenotypic and genotypic strategy. In children, testing is recommended from age 5 years, or earlier if homozygous FH is suspected. A healthy lifestyle and statin treatment (from age 8 to 10 years) are the cornerstones of management of heterozygous FH. Target LDL-C is <3.5 mmol/L (130 mg/dL) if >10 years, or ideally 50% reduction from baseline if 8–10 years, especially with very high LDL-C, elevated lipoprotein(a), a family history of premature CHD or other cardiovascular risk factors, balanced against the long-term risk of treatment side effects. Identifying FH early and optimally lowering LDL-C over the lifespan reduces cumulative LDL-C burden and offers health and socioeconomic benefits. To drive policy change for timely detection and management, we call for further studies in the young. Increased awareness, early identification, and optimal treatment from childhood are critical to adding decades of healthy life for children and adolescents with FH.

Gene therapy for inherited diseases of liver metabolism

Gene therapy is entering the stage of initial clinical development to treat a growing number of inherited metabolic diseases. This review outlines the development of liver-directed gene therapy for diseases caused by deficiencies of enzymes that are primarily expressed in the liver and discusses the disorders that appear most promising for clinical translation.

Homozygous familial hypercholesterolaemia: new insights and guidance for clinicians to improve detection and clinical management. A position paper from the Consensus Panel on Familial Hypercholesterolaemia of the European Atherosclerosis Society

AIMS

Homozygous familial hypercholesterolaemia (HoFH) is a rare life-threatening condition characterized by markedly elevated circulating levels of low-density lipoprotein cholesterol (LDL-C) and accelerated, premature atherosclerotic cardiovascular disease (ACVD). Given recent insights into the heterogeneity of genetic defects and clinical phenotype of HoFH, and the availability of new therapeutic options, this Consensus Panel on Familial Hypercholesterolaemia of the European Atherosclerosis Society (EAS) critically reviewed available data with the aim of providing clinical guidance for the recognition and management of HoFH.

METHODS AND RESULTS

Early diagnosis of HoFH and prompt initiation of diet and lipid-lowering therapy are critical. Genetic testing may provide a definitive diagnosis, but if unavailable, markedly elevated LDL-C levels together with cutaneous or tendon xanthomas before 10 years, or untreated elevated LDL-C levels consistent with heterozygous FH in both parents, are suggestive of HoFH. We recommend that patients with suspected HoFH are promptly referred to specialist centres for a comprehensive ACVD evaluation and clinical management. Lifestyle intervention and maximal statin therapy are the mainstays of treatment, ideally started in the first year of life or at an initial diagnosis, often with ezetimibe and other lipid-modifying therapy. As patients rarely achieve LDL-C targets, adjunctive lipoprotein apheresis is recommended where available, preferably started by age 5 and no later than 8 years. The number of therapeutic approaches has increased following approval of lomitapide and mipomersen for HoFH. Given the severity of ACVD, we recommend regular follow-up, including Doppler echocardiographic evaluation of the heart and aorta annually, stress testing and, if available, computed tomography coronary angiography every 5 years, or less if deemed necessary.

CONCLUSION

This EAS Consensus Panel highlights the need for early identification of HoFH patients, prompt referral to specialized centres, and early initiation of appropriate treatment. These recommendations offer guidance for a wide spectrum of clinicians who are often the first to identify patients with suspected HoFH.

Novel therapies for treating familial hypercholesterolemia

Familial hypercholesterolemia is an inherited disorder associated with early accelerated atherosclerosis with morbidity and mortality resulting from premature cardiovascular disease. Affected individuals have extreme elevations in low-density lipoprotein cholesterol levels. Patients usually do not achieve target reductions in cholesterol levels with conventional antihyperlipidemic pharmacotherapy. This unmet need has resulted in the recent development and approval of novel therapies targeting different cholesterol pathways. This article briefly summarizes familial hypercholesterolemia and then discusses the newer pharmacotherapies available in the management of familial hypercholesterolemia.

Inhibition of hepatic microsomal triglyceride transfer protein - a novel therapeutic option for treatment of homozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the low-density lipoprotein (LDL)-receptor gene (LDLR). Patients with homozygous FH (hoFH) have inherited a mutated LDLR gene from both parents, and therefore all their LDL-receptors are incapable of functioning normally. In hoFH, serum LDL levels often exceed 13 mmol/L and tendon and cutaneous xanthomata appear early (under 10 years of age). If untreated, this extremely severe form of hypercholesterolemia may cause death in childhood or in early adulthood. Based on recent data, it can be estimated that the prevalence of hoFH is about 1:500,000 or even 1:400,000. Until now, the treatment of hoFH has been based on high-dose statin treatment combined with LDL apheresis. Since the LDL cholesterol-lowering effect of statins is weak in this disease, and apheresis is a cumbersome treatment and not available at all centers, alternative novel pharmaceutical therapies are needed. Lomitapide is a newly introduced drug, capable of effectively decreasing serum LDL cholesterol concentration in hoFH. It inhibits the microsomal triglyceride transfer protein (MTTP). By inhibiting in hepatocytes the transfer of triglycerides into very low density lipoprotein particles, the drug blocks their assembly and secretion into the circulating blood. Since the very low density lipoprotein particles are precursors of LDL particles in the circulation, the reduced secretion of the former results in lower plasma concentration of the latter. The greatest concern in lomitapide treatment has been the increase in liver fat, which can be, however, counteracted by strictly adhering to a low-fat diet. Lomitapide is a welcome addition to the meager selection of drugs currently available for the treatment of refractory hypercholesterolemia in hoFH patients.

Familial hypercholesterolemia: an under-recognized but significant concern in cardiology practice

Familial hypercholesterolemia (FH) is a common disorder in which genetic mutations in at least 1 of several genes lead to significantly increased levels of lipoproteins, in particular, low-density lipoprotein cholesterol. Most commonly, mutations in the low-density lipoprotein receptor gene result in high plasma levels of apolipoprotein B-containing lipoproteins (eg, low-density lipoprotein and lipoprotein(a)). High plasma levels of lipoproteins increase the risk of cardiovascular events by as much as 20-fold if left untreated. A 2011 survey of cardiologists performed by the American College of Cardiology (ACC) suggests that there is a need for greater awareness of FH among cardiologists with regard to its prevalence and heritability, and of the risk of cardiovascular (CV) disease associated with the disorder, such as premature coronary heart disease. Given that many patients with FH may first present to CV specialists at the time of a major coronary event, it is critical that cardiologists have strategies to manage this high-risk subset of patients. This brief review responds to areas of need identified in the ACC survey and is intended to provide current information about FH and increase awareness about this disorder among cardiologists.

Fatal myocardial infarction at 4.5 years in a case of homozygous familial hypercholesterolaemia

Management of homozygous familial hypercholesterolaemia is notoriously difficult. For these patients, LDL apheresis is considered the treatment of choice. Treatment initiation is advocated generally from the age of seven years onwards (Thompson et al., Atherosclerosis 198:247-255, 2008). Here, we present the case of a young girl from a large inbred family of Turkish descent with homozygous familial hypercholesterolaemia and fatal outcome at the early age of 4½ years.In conclusion, this case suggests that management of homozygous familial hypercholesterolaemia may require earlier and more aggressive treatment, including LDL apheresis before the age of seven years.