Is Liver Transplant Curative in Homozygous Familial Hypercholesterolemia? A Review of Nine Global Cases

Perioperative management in pediatric domino liver transplantation for metabolic disorders: A narrative review

Domino liver transplantation and domino-auxiliary partial orthotopic liver transplantation are emerging techniques that can expand the liver donor pool and provide hope for children with liver disease. The innovative technique of domino liver transplantation has emerged as a pioneering strategy, capitalizing on structurally preserved livers from donors exhibiting single enzymatic defects within a morphologically normal context, effectively broadening the donor pool. Concurrently, the increasingly prevalent domino-auxiliary partial orthotopic liver transplantation method assumes a critical role in bolstering available donor resources. These advanced transplantation methods present a unique opportunity for pediatric patients who, despite having structurally and functionally intact livers and lacking early signs of portal hypertension or extrahepatic involvement, do not attain priority on conventional transplant lists. Utilizing optimal clinical conditions enhances posttransplant outcomes, benefiting patients who would otherwise endure extended waiting periods for traditional transplantation. The perioperative management of children undergoing these procedures is complex and requires careful consideration of some factors, including clinical and metabolic conditions of the specific metabolic disorder, and the need for tailored perioperative management planning. Furthermore, the prudent consideration of de novo disease development in the recipient assumes paramount significance when selecting suitable donors for domino liver transplantation, as it profoundly influences prognosis, mortality, and morbidity. This narrative review of domino liver transplantation will discuss the pathophysiology, clinical evaluation, perioperative management, and prognostic expectations, focusing on perioperative anesthetic considerations for children undergoing domino liver transplantation.

The therapeutic effect of liver transplantation in 14 children with homozygous familial hypercholesterolemia: a prospective cohort: Liver transplant for familial hypercholesterolemia

OBJECTIVES

Homozygous familial hypercholesterolemia (HoFH) is characterized by elevated low-density lipoprotein cholesterol (LDL-C) and early-onset cardiovascular disease. To assess the therapeutic effects of liver transplantation (LT) on HoFH patients, we observed and analyzed the outcomes of HoFH children after LT.

STUDY DESIGN

This prospective cohort study included all LT candidates under 18 years old diagnosed with HoFH at Ren Ji Hospital between November 2017 and July 2021. The patients were followed until October 2023. They were treated according to the standard protocol at our center. We collected data on changes in lipid profiles, clinical manifestations, and cardiovascular complications at different time points, and recorded postoperative recipient and graft survival.

RESULTS

Fourteen HoFH patients with a median age of 7 (2-12) years were included. Preoperatively, xanthomas and arcus corneas occurred in 14 and 3 patients, respectively, with 10 patients showing mild cardiovascular disease. All patients underwent LT. Recipient and graft survival rates were 100 % over a median follow-up duration of 35 (27-71) months. Median LDL-C levels dropped from 11.83 (7.99-26.14) mmol/L preoperatively to 2.3 (1.49-3.39) mmol/L postoperative at the last measurement. Thirteen patients discontinued lipid-lowering treatment after LT, while only one patient resumed statins 6 months post-operation. Xanthomas and arcus corneas significantly improved. Cardiovascular complications regressed in five patients, with no progression observed in the others.

CONCLUSIONS

LT is a safe and effective treatment for severe HoFH patients beyond lipid-lowering control. Early LT improves prognosis and quality of life while minimizing the risk of cardiovascular complications.

Improved lipid-lowering treatment and reduction in cardiovascular disease burden in homozygous familial hypercholesterolemia: The SAFEHEART follow-up study

AIM

We aimed to describe clinical and genetic characteristics, lipid-lowering treatment and atherosclerotic cardiovascular disease (ASCVD) outcomes over a long-term follow-up in homozygous familial hypercholesterolemia (HoFH).

METHODS

SAFEHEART (Spanish Familial Hypercholesterolaemia Cohort Study) is a long-term study in molecularly diagnosed FH. Data analyzed in HoFH were prospectively obtained from 2004 until 2022. ASCVD events, lipid profile and lipid-lowering treatment were determined.

RESULTS

Thirty-nine HoFH patients were analyzed. The mean age was 42 ± 20 years and nineteen (49%) were women. Median follow-up was 11 years (IQR 6,18). Median age at genetic diagnosis was 24 years (IQR 8,42). At enrolment, 33% had ASCVD and 18% had aortic valve disease. Patients with new ASCVD events and aortic valve disease at follow-up were six (15%), and one (3%), respectively. Median untreated LDL-C levels were 555 mg/dL (IQ 413,800), and median LDL-C levels at last follow-up was 122 mg/dL (IQR 91,172). Most patients (92%) were on high intensity statins and ezetimibe, 28% with PCSK9i, 26% with lomitapide, and 23% with lipoprotein-apheresis. Fourteen patients (36%) attained an LDL-C level below 100 mg/dL, and 10% attained an LDL-C below 70 mg/dL in secondary prevention. Patients with null/null variants were youngers, had higher untreated LDL-C and had the first ASCVD event earlier. Free-event survival is longer in patients with defective variant compared with those patients with at least one null variant (p=0.02).

CONCLUSIONS

HoFH is a severe life threating disease with a high genetic and phenotypic variability. The improvement in lipid-lowering treatment and LDL-C levels have contributed to reduce ASCVD events.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolaemia: An expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is used for decades, lowering serum LDL-C levels by more than 70% directly after the treatment. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment goals and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

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.

The genetics of autosomal dominant familial hypercholesterolemia

ABSTRACT

Familial hypercholesterolemia (FH) is one of the most common genetic conditions. Affected individuals are unable to metabolize cholesterol due to inherited changes in the low-density lipoprotein (LDL) receptor, which impairs the ability to metabolize cholesterol, resulting in extremely high levels of cholesterol that leads to premature coronary artery disease. Autosomal dominant FH is caused by variants in several genes, which may present as heterozygous FH (less severe) or homozygous FH (more severe). Clinical diagnosis may be more likely when there is a family history of two or more first-degree relatives with total and LDL-cholesterol (LDL-C) level elevations, a child is identified, or the affected individual or close relatives have tendon xanthomas and/or progressive atherosclerosis. This article provides an overview of autosomal dominant FH, including disease prevalence, clinical diagnostic criteria, genetic variants, diagnostic testing, pathognomonic findings, and treatment options. It also shares a brief case, which highlights challenges associated with genetic test interpretation and the importance of including experienced providers in the diagnosis and treatment of this underdiagnosed and often untreated or undertreated genetic condition.

Long-term outcomes of liver transplantation for homozygous familial hypercholesterolaemia in Australia and New Zealand

BACKGROUND AND AIMS

Homozygous familial hypercholesterolaemia (FH) causes severe cardiovascular disease from childhood. Conventional drug therapy is usually ineffective; lipoprotein apheresis (LA) is often required. Liver transplantation (LT) can correct the metabolic defect but is considered a treatment of last resort. Newer drugs including lomitapide and evinacumab might reduce the need for apheresis and LT. We sought to determine the long-term outcomes following LT in Australia and New Zealand.

METHODS

We analysed demographic, biochemical and clinical data from all patients in Australia and New Zealand who have received LT for homozygous FH, identified from the Australia and New Zealand Liver and Intestinal Transplant Registry.

RESULTS

Nine patients (five female; one deceased; seven aged between 3 and 6 years at the time of LT and two aged 22 and 26 years) were identified. Mean follow-up was 14.1 years (range 4-27). Baseline LDL-cholesterol off all treatment was 23 ± 4.1 mmol/L. Mean LDL-cholesterol on medical therapy (including maximal statin therapy in all patients, ezetimibe in three and LA in five) was 11 ± 5.7 mmol/L (p < 0.001). After LT, mean LDL-cholesterol was 2.6 ± 0.9 mmol/L (p = 0.004) with three patients remaining on statin therapy and none on LA. One patient died from acute myocardial infarction (AMI) three years after LT. Two patients required aortic valve replacement, more than 10 years after LT. The remaining six patients were asymptomatic after eight to 21 years of follow-up. No significant adverse events associated with immunosuppression were reported.

CONCLUSIONS

LT for homozygous FH was highly effective in achieving substantial long-term reduction in LDL-cholesterol concentrations in all nine patients. LT remains an option for severe cases of homozygous FH where drug therapy combined with apheresis is ineffective or unfeasible.

International Atherosclerosis Society guidance for implementing best practice in the care of familial hypercholesterolaemia

This contemporary, international, evidence-informed guidance aims to achieve the greatest good for the greatest number of people with familial hypercholesterolaemia (FH) across different countries. FH, a family of monogenic defects in the hepatic LDL clearance pathway, is a preventable cause of premature coronary artery disease and death. Worldwide, 35 million people have FH, but most remain undiagnosed or undertreated. Current FH care is guided by a useful and diverse group of evidence-based guidelines, with some primarily directed at cholesterol management and some that are country-specific. However, none of these guidelines provides a comprehensive overview of FH care that includes both the lifelong components of clinical practice and strategies for implementation. Therefore, a group of international experts systematically developed this guidance to compile clinical strategies from existing evidence-based guidelines for the detection (screening, diagnosis, genetic testing and counselling) and management (risk stratification, treatment of adults or children with heterozygous or homozygous FH, therapy during pregnancy and use of apheresis) of patients with FH, update evidence-informed clinical recommendations, and develop and integrate consensus-based implementation strategies at the patient, provider and health-care system levels, with the aim of maximizing the potential benefit for at-risk patients and their families worldwide.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolemia: an expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is well established since three decades, lowering serum LDL-C levels by more than 70% per session. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment targets and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Recent advances in the management and implementation of care for familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a common autosomal semi-dominant and highly penetrant disorder of the low-density lipoprotein (LDL) receptor pathway, characterised by lifelong elevated levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of atherosclerotic cardiovascular disease (ASCVD). However, many patients with FH are not diagnosed and do not attain recommended LDL-C goals despite maximally tolerated doses of potent statin and ezetimibe. Over the past decade, several cholesterol-lowering therapies such as those targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) or angiopoietin-like 3 (ANGPTL3) with monoclonal antibody or ribonucleic acid (RNA) approaches have been developed that promise to close the treatment gap. The availability of new therapies with complementary modes of action of lipid metabolism has enabled many patients with FH to attain guideline-recommended LDL-C goals. Emerging therapies for FH include liver-directed gene transfer of the LDLR, vaccines targeting key proteins involved in cholesterol metabolism, and CRISPR-based gene editing of PCSK9 and ANGPTL3, but further clinical trials are required. In this review, current and emerging treatment strategies for lowering LDL-C, and ASCVD risk-stratification, as well as implementation strategies for the care of patients with FH are reviewed.

In vitro assessment of the pathogenicity of the LDLR c.2160delC variant in familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an inherited disorder with markedly elevated low-density lipoprotein cholesterol (LDL-C) and premature atherosclerotic cardiovascular disease. Although many mutations have been reported in FH, only a few have been identified as pathogenic mutations. This study aimed to confirm the pathogenicity of the LDL receptor (LDLR) c.2160delC variant in FH.

METHODS

In this study, the proband and her family members were systematically investigated, and a pedigree map was drawn. High-throughput whole-exome sequencing was used to explore the variants in this family. Next, quantitative polymerase chain reaction (qPCR), western blot (WB) assays, and flow cytometry were conducted to detect the effect of the LDLR c.2160delC variant on its expression. The LDL uptake capacity and cell localization of LDLR variants were analyzed by confocal microscopy.

RESULTS

According to Dutch Lipid Clinic Network (DLCN) diagnostic criteria, three FH patients were identified with the LDLR c.2160delC variant in this family. An in-silico analysis suggested that the deletion mutation at the 2160 site of LDLR causes a termination mutation. The results of qPCR and WB verified that the LDLR c.2160delC variant led to early termination of LDLR gene transcription. Furthermore, the LDLR c.2160delC variant caused LDLR to accumulate in the endoplasmic reticulum, preventing it from reaching the cell surface and internalizing LDL.

CONCLUSIONS

The LDLR c.2160delC variant is a terminating mutation that plays a pathogenic role in FH.

2023 Update on European Atherosclerosis Society Consensus Statement on Homozygous Familial Hypercholesterolaemia: new treatments and clinical guidance

This 2023 statement updates clinical guidance for homozygous familial hypercholesterolaemia (HoFH), explains the genetic complexity, and provides pragmatic recommendations to address inequities in HoFH care worldwide. Key strengths include updated criteria for the clinical diagnosis of HoFH and the recommendation to prioritize phenotypic features over genotype. Thus, a low-density lipoprotein cholesterol (LDL-C) >10 mmol/L (>400 mg/dL) is suggestive of HoFH and warrants further evaluation. The statement also provides state-of-the art discussion and guidance to clinicians for interpreting the results of genetic testing and for family planning and pregnancy. Therapeutic decisions are based on the LDL-C level. Combination LDL-C-lowering therapy-both pharmacologic intervention and lipoprotein apheresis (LA)-is foundational. Addition of novel, efficacious therapies (i.e. inhibitors of proprotein convertase subtilisin/kexin type 9, followed by evinacumab and/or lomitapide) offers potential to attain LDL-C goal or reduce the need for LA. To improve HoFH care around the world, the statement recommends the creation of national screening programmes, education to improve awareness, and management guidelines that account for the local realities of care, including access to specialist centres, treatments, and cost. This updated statement provides guidance that is crucial to early diagnosis, better care, and improved cardiovascular health for patients with HoFH worldwide.

Management and clinical outcomes of patients with homozygous familial hypercholesteremia in Saudi Arabia

We report the incidence, patient characteristic with clinical outcomes in patients with homozygous familial hypercholesterolemia (HoFH) in Saudi Arabia. This is a retrospective and prospective, single center study which included 37 patients 14 years and older enrolled and followed up between 2018-2021 for three years. 46% were females, 78% were offspring of consanguineous marriage. LDLR mutation was in 78% and LDL-C/LDLRAP in 3% of patients. Mean LDL-C at the first presentation was 14.2±3.7 mmol/L, average Dutch lipid score was 20.9±6.24. LDL apheresis was performed on 70% of patients. Most patients were on ezetimibe (92%), high-dose statins ( 84%) and  PCSK9 inhibitors (32%). 48.6% had aortic stenosis, out of which 30% had severe aortic stenosis. Ten underwent aortic valve surgery (5 mechanical valve, 3 Ross procedure, 1 aortic valve repair, 1 bioprosthetic valve) and one had transcatheter aortic valve implantation (TAVI). Coronary artery bypass surgery (CABG) was performed on 32% and percutaneous intervention (PCI) on 11% of patients. HoFH patients have complex diseases with high morbidity and mortality, and benefit from a highly specialized multidisciplinary clinic to address their clinical needs. Although there are several therapeutic agents on the horizon, early diagnosis, and treatment of HoFH remain critical to optimize patient outcomes.

Current Treatment Options in Homozygous Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is the rare form of familial hypercholesterolemia causing extremely high low-density lipoprotein cholesterol (LDL-C) levels, leading to atherosclerotic cardiovascular disease (ASCVD) in the first decades of life, if left untreated. Early diagnosis and effective lipid lowering therapy (LLT) are crucial for the prevention of early ASCVD in patients with HoFH. On-treatment LDL-C levels are the best predictor of survival. However, due to the absent or defective LDL-receptor activity, most individuals with HoFH are resistant to conventional LLT, that leads to LDL-C clearance by upregulating LDL-receptors. We are at the dawn of a new era of effective pharmacotherapies for HoFH patients, with new agents providing an LDL-receptor independent cholesterol reduction. In this context, the present review provides a summary of the currently available therapies and emerging therapeutic agents for the management of patients with HoFH, in light of recent evidence and guideline recommendations.

New algorithms for treating homozygous familial hypercholesterolemia

PURPOSE OF REVIEW

We reviewed current and future therapeutic options for patients with homozygous familial hypercholesterolemia (HoFH) and place this evidence in context of an adaptable treatment algorithm.

RECENT FINDINGS

Lowering LDL-C levels to normal in patients with HoFH is challenging, but a combination of multiple lipid-lowering therapies (LLT) is key. Patients with (near) absence of LDL receptor expression are most severely affected and frequently require regular lipoprotein apheresis on top of combined pharmacologic LLT. Therapies acting independently of the LDL receptor pathway, such as lomitapide and evinacumab, are considered game changers for many patients with HoFH, and may reduce the need for lipoprotein apheresis in future. Liver transplantation is to be considered a treatment option of last resort. Headway is being made in gene therapy strategies, either aiming to permanently replace or knock out key lipid-related genes, with first translational steps into humans being made. Cardiovascular disease risk management beyond LDL-C, such as residual Lp(a) or inflammatory risk, should be evaluated and addressed accordingly in HoFH.

SUMMARY

Hypercholesterolemia is notoriously difficult to control in most patients with HoFH, but multi-LLT, including newer drugs, allows reduction of LDL-C to levels unimaginable until a few years ago. Cost and availability of these new therapies are important future challenges to be addressed.

Perioperative Management and Clinical Outcomes of Liver Transplantation for Children with Homozygous Familial Hypercholesterolemia

Background and Objectives: Liver transplantation (LT) has been accepted as a life-saving option as a last resort for children with homozygous familial hypercholesterolemia (HoFH). Perioperative management of LT for HoFH poses extra challenges for clinicians largely due to premature atherosclerotic cardiovascular diseases (ASCVDs). We aimed to analyze our data of pediatric LT recipients with HoFH, with special attention paid to perioperative management and clinical outcomes. Materials and Methods: After obtaining approval from the local ethics committee, the clinical data of pediatric patients with HoFH who underwent LT at our institution between January 2014 and February 2021 were retrospectively studied. Results: Six pediatric LT recipients with HoFH were included in the analysis. Although ASCVDs were common before LT, all children with HoFH survived the perioperative period without in-hospital mortality. However, one patient experienced acute myocardial infarction two months following LT and was successfully treated with medical interventions. Post-LT metabolic improvement was shown by declines in serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels in the early post-LT period (for TC: 14.7 ± 3.2 mmol/L vs. 5.5 ± 1.8 mmol/L, p < 0.001; for LDL-C: 10.6 ± 2.2 mmol/L vs. 3.6 ± 1.2 mmol/L, p < 0.001, respectively) and at the last follow-up (for TC: 14.7 ± 3.2 mmol/L vs. 4.5 ± 0.9 mmol/L, p = 0.001; for LDL-C: 10.6 ± 2.2 mmol/L vs. 2.8 ± 0.6 mmol/L, p = 0.001, respectively). Dietary restrictions could be lifted after LT. However, three patients required restarting lipid-lowering therapy after LT due to suboptimal LDL-C levels and progression of ASCVDs. Conclusions: Our data suggest that LT can be a safe and feasible therapeutic option for well-selected patients with HoFH, offering relaxed dietary restrictions and remarkable reductions in LDL-C levels. However, concerns remain regarding progression of ASCVDs after LT.