Familial hypercholesterolaemia: evolving knowledge for designing adaptive models of care

Implementation of a primary-tertiary shared care model to improve the detection of familial hypercholesterolaemia (FH): a mixed methods pre-post implementation study protocol

INTRODUCTION

Familial hypercholesterolaemia (FH) is an autosomal dominant inherited disorder of lipid metabolism and a preventable cause of premature cardiovascular disease. Current detection rates for this highly treatable condition are low. Early detection and management of FH can significantly reduce cardiac morbidity and mortality. This study aims to implement a primary-tertiary shared care model to improve detection rates for FH. The primary objective is to evaluate the implementation of a shared care model and support package for genetic testing of FH. This protocol describes the design and methods used to evaluate the implementation of the shared care model and support package to improve the detection of FH.

METHODS AND ANALYSIS

This mixed methods pre-post implementation study design will be used to evaluate increased detection rates for FH in the tertiary and primary care setting. The primary-tertiary shared care model will be implemented at NSW Health Pathology and Sydney Local Health District in NSW, Australia, over a 12-month period. Implementation of the shared care model will be evaluated using a modification of the implementation outcome taxonomy and will focus on the acceptability, evidence of delivery, appropriateness, feasibility, fidelity, implementation cost and timely initiation of the intervention. Quantitative pre-post and qualitative semistructured interview data will be collected. It is anticipated that data relating to at least 62 index patients will be collected over this period and a similar number obtained for the historical group for the quantitative data. We anticipate conducting approximately 20 interviews for the qualitative data.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the ethics review committee (Royal Prince Alfred Hospital Zone) of the Sydney Local Health District (Protocol ID: X23-0239). Findings will be disseminated through peer-reviewed publications, conference presentations and an end-of-study research report to stakeholders.

Enhanced identification of familial hypercholesterolemia using central laboratory algorithms

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a highly prevalent genetic disorder resulting in markedly elevated LDL cholesterol levels and premature coronary artery disease. FH underdiagnosis and undertreatment require novel detection methods. This study evaluated the effectiveness of using an LDL cholesterol cut-off ≥99.5th percentile (sex- and age-adjusted) to identify clinical and genetic FH, and investigated underutilization of genetic testing and undertreatment in FH patients.

METHODS

Individuals with at least one prior LDL cholesterol level ≥99.5th percentile were selected from a laboratory database containing lipid profiles of 590,067 individuals. The study comprised three phases: biochemical validation of hypercholesterolemia, clinical identification of FH, and genetic determination of FH.

RESULTS

Of 5614 selected subjects, 2088 underwent lipid profile reassessment, of whom 1103 completed the questionnaire (mean age 64.2 ± 12.7 years, 48% male). In these 1103 subjects, mean LDL cholesterol was 4.0 ± 1.4 mmol/l and 722 (65%) received lipid-lowering therapy. FH clinical diagnostic criteria were met by 282 (26%) individuals, of whom 85% had not received guideline-recommended genetic testing and 97% failed to attain LDL cholesterol targets. Of 459 individuals consenting to genetic validation, 13% carried an FH-causing variant, which increased to 19% in clinically diagnosed FH patients.

CONCLUSIONS

The identification of a substantial number of previously undiagnosed and un(der)treated clinical and genetic FH patients within a central laboratory database highlights the feasibility and clinical potential of this targeted screening strategy; both in identifying new FH patients and in improving treatment in this high-risk population.

Sex differences in the presentation, treatment and outcomes of patients with homozygous familial hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is a rare, autosomal semi-dominant lipid metabolism disorder characterized by extremely high low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease. The objective of this study was to investigate sex-differences in the treatment and outcomes of patients with HoFH.

METHODS

We examined clinical characteristics, lipid-lowering therapy (LLT), and cardiovascular events using descriptive statistics of patients in the Canadian HoFH registry. Major adverse cardiovascular events (MACE) were defined as the composite of cardiovascular death, non-fatal myocardial infarction, and stroke. Sex differences between continuous and categorical variables were analyzed using Mann-Whitney U test and Fisher's Exact test, respectively.

RESULTS

This study included 48 patients (27 (56%) female). The median age at diagnosis in females was 14.0 (interquartile range (IQR) 9.0-30.0) and in males was 8.0 (IQR 2.0-23.0) (p = 0.07). Baseline clinical characteristics were comparable between both sexes. The median baseline LDL-C was 12.7 mmol/L (10.0-18.3) in females and 15.3 (10.5-20.0) in males (p = 0.51). Follow up LDL-C levels were 7.6 mmol/L (IQR 4.8-11.0) in females and 6.3 (IQR 4.6-7.5) in males (p = 0.1). Most patients were taking 3 or more LLTs, with comparable proportions in both sexes (p = 0.26). Apheresis was similar in both sexes, 14 (51.8%) vs. 10 (47.6%) (p = 0.2). Over a mean of 10 years of follow-up, MACE occurred in 3 females (11.1%) and 4 males (19.1%) (p = 0.2).

CONCLUSION

Lipid levels and treatment were similar between sexes. MACE occurred in similar proportions between sexes, indicating that HoFH offsets the inherently lower cardiovascular risk in pre-menopausal females. Further investigation into sex-differences in HoFH in larger sample sizes is warranted.

Adherence to pharmacotherapy: sine qua non for reducing cumulative risk of premature coronary disease in familial hypercholesterolemia

PURPOSE OF REVIEW

Familial hypercholesterolemia (FH) is a dominant and highly penetrant monogenic disorder present from birth that markedly elevates plasma low-density lipoprotein (LDL)-cholesterol concentration and, if untreated, leads to atherosclerotic cardiovascular disease (ASCVD). The risk of ASCVD can be substantially reduced with lipid-lowering treatment (LLT). However, adherence to LLT remains a major challenge in FH patients and an under-recognized issue. We review several barriers to treatment adherence and implementation strategies for improving adherence in patients with FH.

RECENT FINDINGS

Barriers that negatively affect patient adherence to treatment include the misunderstanding of perceived and actual risk of FH and the benefits of LLT, inadequate knowledge, lack of standardization of treatment, insufficient monitoring of LDL-cholesterol level, and inequalities in healthcare resources. Education of patients, carers and healthcare providers, guideline-directed treatment goals, regular monitoring, medication regimen simplification and greater access to established and new drugs are crucial enablers for improving adherence to treatment. However, given FH is present from birth, strategies for life-long adherence from childhood or young adulthood is critically important and requires further study. To be effective, strategies should be multifaceted, targeted and patient-centred involving a multidisciplinary-team with support from family, communities and peer groups.

SUMMARY

FH confers a significant risk for ASCVD from a young age. Achieving better medication adherence is foundational for improving clinical outcomes and reducing the burden of atherosclerosis over a lifetime. Identification of key barriers and enablers are critical for implementing better adherence to treatment across the life-course of patients with FH.

International Atherosclerosis Society Roadmap for Familial Hypercholesterolaemia

Familial hypercholesterolaemia (FH), a common monogenic disorder, is a preventable cause of premature coronary artery disease and death. Up to 35 million people worldwide have FH, but most remain undetected and undertreated. Several clinical guidelines have addressed the gaps in care of FH, but little focus has been given to implementation science and practice. The International Atherosclerosis Society (IAS) has developed an evidence-informed guidance for the detection and management of patients with FH, supplemented with implementation strategies to optimize contextual models of care. The guidance is partitioned into detection, management and implementation sections. Detection deals with screening, diagnosis, genetic testing and counselling. Management includes risk stratification, treatment of adults and children with heterozygous and homozygous FH, management of FH during pregnancy, and use of lipoprotein apheresis. Specific and general implementation strategies, guided by processes specified by the Expert Recommendations for Implementing Change taxonomy, are provided. Core generic implementation strategies are given for improving care. Nation-specific cholesterol awareness campaigns should be utilized to promote better detection of FH. Integrated models of care should be underpinned by health policy and adapted to meet local, regional and national needs. Clinical centres of excellence are important for taking referrals from the community. General practitioners should work seamlessly with multidisciplinary teams. All health-care providers must receive training in essential skills for caring for patients and families with FH. Management should be supported by shared decision-making and service improvement driven by patient-reported outcomes. Improvements in services require sharing of existing resources that can support care. Advocacy should be utilized to ensure sustainable funding. Digital health technologies and clinical quality registries have special value. Finally, academic-service partnerships need to be developed to identify gaps in care and set priorities for research. This new IAS guidance on FH complements the recent World Heart Federation Cholesterol Roadmap.

Predictors of cardiovascular risk in familial hypercholesterolemia

PURPOSE OF REVIEW

Familial hypercholesterolemia is associated with an increased risk of cardiovascular disease. The current international guidelines of the main scientific societies consider that, all people with Familial Hypercholesterolemia have a high or very high cardiovascular risk. However, the occurrence of atherosclerotic cardiovascular disease is very heterogeneous in this population. Stratifying risk within people with familial hypercholesterolemia is essential to identify individuals who require intensive cholesterol-lowering therapies.

RECENT FINDINGS

In the last year, several studies have been published focusing on the contribution of diabetes to Familial Hypercholesterolemia, the role of stroke, as a manifestation of atherosclerotic disease, and the external validation of the SAFEHEART risk equation in the English population diagnosed with Familial Hypercholesterolemia.

SUMMARY

It is necessary the development of a tool that allows us to identify, in a simple, reproducible, and universal way, patients who may have a high risk of suffering a cardiovascular event and who are susceptible to more intensive treatments to reduce cholesterol levels.

Stratification in Heterozygous Familial Hypercholesterolemia: Imaging, Biomarkers, and Genetic Testing

PURPOSE OF REVIEW

Heterozygous familial hypercholesterolemia (HeFH) is the most common monogenic autosomal dominant disorder. However, the condition is often underdiagnosed and undertreated. The objective of this review is to provide an update on the risk stratification in patients with HeFH, incorporating new cardiovascular imaging techniques, various biomarkers, and genetic studies.

RECENT FINDINGS

The diagnosis of HeFH places patients in a high cardiovascular risk category due to the increased incidence of premature atherosclerotic cardiovascular disease. However, the level of risk varies significantly among different individuals with HeFH. Achieving an optimal stratification of cardiovascular risk is crucial for establishing appropriate and accurate treatment and management strategies. Different new tools such as risk scores have emerged in recent years, aiding physicians in assessing the risk stratification for HeFH using imaging, biomarkers, and genetics. This review emphasizes that not all patients with HeFH face the same cardiovascular risk. By utilizing different assessment tools, we can identify those who require more intensive monitoring, follow-up, and treatment.

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.

The Promise of PCSK9 and Lipoprotein(a) as Targets for Gene Silencing Therapies

PURPOSE

High plasma concentrations of LDL and lipoprotein(a) (Lp[a]) are independent and causal risk factors for atherosclerotic cardiovascular disease (ASCVD). There is an unmet therapeutic need for high-risk patients with elevated levels of LDL-C and/or Lp(a). Recent advances in the development of nucleic acids for gene silencing (ie, triantennary N-acetylgalactosamine conjugated antisense-oligonucleotides [ASOs] and small interfering RNA [siRNA]) targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) and Lp(a) offer effective and sustainable therapies.

METHODS

Related articles in the English language were identified through a search for original and review articles in the PubMed database using the following key terms: cardiovascular disease, dyslipidemia, PCSK9 inhibitors, Lp(a), LDL-cholesterol, familial hypercholesterolemia, siRNA, and antisense oligonucleotide and clinical trials (either alone or in combination).

FINDINGS

Inclisiran, the most advanced siRNA-treatment targeting hepatic PCSK9, is well tolerated, producing a >30% reduction on LDL-C levels in randomized controlled trials. Pelacarsen is the most clinical advanced ASO, whereas olpasiran and SLN360 are the 2 siRNAs directed against the mRNA of the LPA gene. Evidence suggests that all Lp(a)-targeting agents are safe and well tolerated, with robust and sustained reduction in plasma Lp(a) concentration up to 70% to 90% in individuals with elevated Lp(a) levels.

IMPLICATIONS

Cumulative evidence from clinical trials supports the value of ASO and siRNA therapies targeting the synthesis of PCSK9 and Lp(a) for lowering LDL-C and Lp(a) in patients with established ASCVD or high risk of ASCVD. Further research is needed to examine whether gene silencing therapy could improve clinical outcomes in patients with elevated LDL and/or Lp(a) levels. Confirmation of the tolerability and cost-effectiveness of long-term inhibition of PCSK9 and Lp(a) with this approach is essential.

Decreased Serum Stromal Cell-Derived Factor-1 in Patients with Familial Hypercholesterolemia and Its Strong Correlation with Lipoprotein Subfractions

Stromal cell-derived factor-1 (SDF-1) is a chemokine that exerts multifaceted roles in atherosclerosis. However, its association with hyperlipidemia is contradictory. To date, serum SDF-1 and its correlations with lipid fractions and subfractions in heterozygous familial hypercholesterolemia (HeFH) have not been investigated. Eighty-one untreated patients with HeFH and 32 healthy control subjects were enrolled in the study. Serum SDF-1, oxidized LDL (oxLDL) and myeloperoxidase (MPO) were determined by ELISA. Lipoprotein subfractions were detected by Lipoprint. We diagnosed FH using the Dutch Lipid Clinic Network criteria. Significantly lower serum SDF-1 was found in HeFH patients compared to healthy controls. Significant negative correlations were detected between serum total cholesterol, triglycerides, LDL-cholesterol (LDL-C), apolipoprotein B100 (ApoB100) and SDF-1. Furthermore, serum SDF-1 negatively correlated with VLDL and IDL, as well as large LDL and large and intermediate HDL subfractions, while there was a positive correlation between mean LDL-size, small HDL and SDF-1. SDF-1 negatively correlated with oxLDL and MPO. A backward stepwise multiple regression analysis showed that the best predictors of serum SDF-1 were VLDL and oxLDL. The strong correlation of SDF-1 with lipid fractions and subfractions highlights the potential common pathways of SDF-1 and lipoprotein metabolism, which supports the role of SDF-1 in atherogenesis.

Screening and verifying the mutations in the LDLR and APOB genes in a Chinese family with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disorder. The primary objective of this study was to identify the major pathogenic mutations in a Chinese family with FH.

METHODS

Whole-genome sequencing (WGS) was used to identify variants of FH-related genes, including low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9). Bioinformatics software was used to predict signal peptides, transmembrane structures, and spatial construction information of the mutated sequences. Western blotting was performed on the mutant protein to determine the presence of the major structural domains of the LDLR. The PCSK9 and APOB genes were screened and analyzed. Moreover, the proband and his brother were treated with a PCSK9 inhibitor for 1 year, and the effect of the treatment on lipid levels was assessed.

RESULTS

WGS revealed two potentially pathogenic mutations in the LDLR gene. One was a novel mutation, c.497delinsGGATCCCCCAGCTGCATCCCCCAG (p. Ala166fs), and the other was a known pathogenic mutation, c.2054C>T (p. Pro685Leu). Bioinformatics prediction and in vitro experiments revealed that the novel mutation could not be expressed on the cell membrane. Numerous gene variants were identified in the APOB gene that may have a significant impact on the family members with FH. Thus, it is suggested that the severe manifestation of FH in the proband primarily resulted from the cumulative genetic effects of variants in both LDLR and APOB. However, a subsequent study indicated that treatment with a PCSK9 inhibitor (Evolocumab) did not significantly reduce the blood lipid levels in the proband or his brother.

CONCLUSIONS

The cumulative effect of LDLR and APOB variants was the primary cause of elevated blood lipid levels in this family. However, PCSK9 inhibitor therapy did not appear to be beneficial for the proband. This study emphasizes the importance of genetic testing in determining the most suitable treatment options for patients with FH.

Subtyping Severe Hypercholesterolemia by Genetic Determinant to Stratify Risk of Coronary Artery Disease

BACKGROUND

Severe hypercholesterolemia, defined as LDL (low-density lipoprotein) cholesterol (LDL-C) measurement ≥190 mg/dL, is associated with increased risk for coronary artery disease (CAD). Causes of severe hypercholesterolemia include monogenic familial hypercholesterolemia, polygenic hypercholesterolemia, elevated lipoprotein(a) [Lp(a)] hypercholesteremia, polygenic hypercholesterolemia with elevated Lp(a) (two-hit), or nongenetic hypercholesterolemia. The added value of using a genetics approach to stratifying risk of incident CAD among those with severe hypercholesterolemia versus using LDL-C levels alone for risk stratification is not known.

METHODS

To determine whether risk stratification by genetic cause provided better 10-year incident CAD risk stratification than LDL-C level, a retrospective cohort study comparing incident CAD risk among severe hypercholesterolemia subtypes (genetic and nongenetic causes) was performed among 130 091 UK Biobank participants. Analyses were limited to unrelated, White British or Irish participants with available exome sequencing data. Participants with cardiovascular disease at baseline were excluded from analyses of incident CAD.

RESULTS

Of 130 091 individuals, 68 416 (52.6%) were women, and the mean (SD) age was 56.7 (8.0) years. Of the cohort, 9.0% met severe hypercholesterolemia criteria. Participants with LDL-C between 210 and 229 mg/dL and LDL-C ≥230 mg/dL showed modest increases in incident CAD risk relative to those with LDL-C between 190 and 209 mg/dL (210-229 mg/dL: hazard ratio [HR], 1.3 [95% CI, 1.1-1.7]; ≥230 mg/dL: HR, 1.3 [95% CI, 1.0-1.7]). In contrast, when risk was stratified by genetic subtype, monogenic familial hypercholesterolemia, elevated Lp(a), and two-hit hypercholesterolemia subtypes had increased rates of incident CAD relative to the nongenetic hypercholesterolemia subtype (monogenic familial hypercholesterolemia: HR, 2.3 [95% CI, 1.4-4.0]; elevated Lp(a): HR, 1.5 [95% CI, 1.2-2.0]; two-hit: HR, 1.9 [95% CI, 1.4-2.6]), while polygenic hypercholesterolemia did not.

CONCLUSIONS

Genetics-based subtyping for monogenic familial hypercholesterolemia and Lp(a) in those with severe hypercholesterolemia provided better stratification of 10-year incident CAD risk than LDL-C-based stratification.

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.

Metabolic systems approaches update molecular insights of clinical phenotypes and cardiovascular risk in patients with homozygous familial hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is an orphan metabolic disease characterized by extremely elevated low-density lipoprotein cholesterol (LDL-C), xanthomas, aortic stenosis, and premature atherosclerotic cardiovascular disease (ASCVD). In addition to LDL-C, studies in experimental models and small clinical populations have suggested that other types of metabolic molecules might also be risk factors responsible for cardiovascular complications in HoFH, but definitive evidence from large-scale human studies is still lacking. Herein, we aimed to comprehensively characterize the metabolic features and risk factors of human HoFH by using metabolic systems strategies.

METHODS

Two independent multi-center cohorts with a total of 868 individuals were included in the cross-sectional study. First, comprehensive serum metabolome/lipidome-wide analyses were employed to identify the metabolomic patterns for differentiating HoFH patients (n = 184) from heterozygous FH (HeFH, n = 376) and non-FH (n = 100) subjects in the discovery cohort. Then, the metabolomic patterns were verified in the validation cohort with 48 HoFH patients, 110 HeFH patients, and 50 non-FH individuals. Subsequently, correlation/regression analyses were performed to investigate the associations of clinical/metabolic alterations with typical phenotypes of HoFH. In the prospective study, a total of 84 HoFH patients with available follow-up were enrolled from the discovery cohort. Targeted metabolomics, deep proteomics, and random forest approaches were performed to investigate the ASCVD-associated biomarkers in HoFH patients.

RESULTS

Beyond LDL-C, various bioactive metabolites in multiple pathways were discovered and validated for differentiating HoFH from HoFH and non-FH. Our results demonstrated that the inflammation and oxidative stress-related metabolites in the pathways of arachidonic acid and lipoprotein(a) metabolism were independently associated with the prevalence of corneal arcus, xanthomas, and supravalvular/valvular aortic stenosis in HoFH patients. Our results also identified a small marker panel consisting of high-density lipoprotein cholesterol, lipoprotein(a), apolipoprotein A1, and eight proinflammatory and proatherogenic metabolites in the pathways of arachidonic acid, phospholipid, carnitine, and sphingolipid metabolism that exhibited significant performances on predicting first ASCVD events in HoFH patients.

CONCLUSIONS

Our findings demonstrate that human HoFH is associated with a variety of metabolic abnormalities and is more complex than previously known. Furthermore, this study provides additional metabolic alterations that hold promise as residual risk factors in HoFH population.

Frequent questions and responses on the 2022 lipoprotein(a) consensus statement of the European Atherosclerosis Society

In 2022, the European Atherosclerosis Society (EAS) published a new consensus statement on lipoprotein(a) [Lp(a)], summarizing current knowledge about its causal association with atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis. One of the novelties of this statement is a new risk calculator showing how Lp(a) influences lifetime risk for ASCVD and that global risk may be underestimated substantially in individuals with high or very high Lp(a) concentration. The statement also provides practical advice on how knowledge about Lp(a) concentration can be used to modulate risk factor management, given that specific and highly effective mRNA-targeted Lp(a)-lowering therapies are still in clinical development. This advice counters the attitude: "Why should I measure Lp(a) if I can't lower it?". Subsequent to publication, questions have arisen relating to how the recommendations of this statement impact everyday clinical practice and ASCVD management. This review addresses 30 of the most frequently asked questions about Lp(a) epidemiology, its contribution to cardiovascular risk, Lp(a) measurement, risk factor management and existing therapeutic options.

Alirocumab and Coronary Atherosclerosis in Asymptomatic Patients with Familial Hypercholesterolemia: The ARCHITECT Study

BACKGROUND

The effect of alirocumab, a PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor, on coronary plaque burden in patients with familial hypercholesterolemia has not been addressed. Our aim was to assess changes in coronary plaque burden and its characteristics after treatment with alirocumab by quantification and characterization of atherosclerotic plaque throughout the coronary tree on the basis of a noninvasive analysis of coronary computed tomographic angiography in asymptomatic subjects with familial hypercholesterolemia receiving optimized and stable treatment with maximum tolerated statin dose with or without ezetimibe.

METHODS

This study is a phase IV, open-label, multicenter, single-arm clinical trial to assess changes in coronary plaque burden and its characteristics after 78 weeks of treatment with alirocumab in patients with familial hypercholesterolemia without clinical atherosclerotic cardiovascular disease. Participants underwent an initial coronary computed tomographic angiography at baseline and another at 78 weeks. Every patient received 150 mg of alirocumab subcutaneiously every 14 days in addition to high-intensity statin therapy. The main outcome was the change on coronary plaque burden and its characteristics by quantification and characterization of atherosclerotic plaque throughout the coronary tree on the basis of analysis of coronary computed tomographic angiography.

RESULTS

The study was completed by 104 patients. The median age was 53.3 (46.2-59.4) years. Of these patients, 54 were women (51.9%). Median low-density lipoprotein cholesterol was 138.9 (117.5-175.3) mg/dL at entry and 45.0 (36.0-65.0) mg/dL at follow-up (P<0.001). Coronary plaque burden changed from 34.6% (32.5%-36.8%) at entry to 30.4% (27.4%-33.4%) at follow-up (P<0.001). A significant change in the characteristics of the coronary atherosclerosis was also found: an increase in the proportion of calcified (+0.3%; P<0.001) and mainly fibrous (+6.2%; P<0.001) plaque, accompanied by a decrease in the percentage of fibro-fatty (-3.9%; P<0.001) and necrotic plaque (-0.6%; P<0.001).

CONCLUSIONS

Treatment with alirocumab in addition to high-intensity statin therapy resulted in significant regression of coronary plaque burden and plaque stabilization on coronary computed tomographic angiography over 78 weeks in these groups of patients with familial hypercholesterolemia without clinical atherosclerotic cardiovascular disease. ARCHITECT (Effect of Alirocumab on Atherosclerotic Plaque Volume, Architecture and Composition) could link and explain ODYSSEY OUTCOMES (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) results.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT05465278.

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.

Designing implementation strategies to improve identification, cascade testing, and management of families with familial hypercholesterolemia: An intervention mapping approach

Introduction

Familial hypercholesterolemia (FH) is a common inherited cholesterol disorder that, without early intervention, leads to premature cardiovascular disease. Multilevel strategies that target all components of FH care including identification, cascade testing, and management are needed to address gaps that exist in FH care. We utilized intervention mapping, a systematic implementation science approach, to identify and match strategies to existing barriers and develop programs to improve FH care.

Methods

Data were collected utilizing two methods: a scoping review of published literature, related to any component of FH care, and a parallel mixed method study using interviews and surveys. The scientific literature was searched using key words including "barriers" or "facilitators" and "familial hypercholesterolemia" from inception to December 1, 2021. The parallel mixed method study recruited individuals and families with FH to participate in either dyadic interviews (N = 11 dyads/22 individuals) or online surveys (N = 98 respondents). Data generated from the scoping review, dyadic interviews, and online surveys were used in the 6-step intervention mapping process. Steps 1-3 included a needs assessment, development of program outcomes and creation of evidence-based implementation strategies. Steps 4-6 included program development, implementation, and evaluation of implementation strategies.

Results

In steps 1-3, a needs assessment found barriers to FH care included underdiagnosis of the condition which led to suboptimal management due to a myriad of determinants including knowledge gaps, negative attitudes, and risk misperceptions by individuals with FH and clinicians. Literature review highlighted barriers to FH care at the health system level, notably the relative lack of genetic testing resources and infrastructure needed to support FH diagnosis and treatment. Examples of strategies to overcome identified barriers included development of multidisciplinary care teams and educational programs. In steps 4-6, an NHLBI-funded study, the Collaborative Approach to Reach Everyone with FH (CARE-FH), deployed strategies that focused on improving identification of FH in primary care settings. The CARE-FH study is used as an example to describe program development, implementation, and evaluation techniques of implementation strategies.

Conclusion

The development and deployment of evidence-based implementation strategies that address barriers to FH care are important next steps to improve identification, cascade testing, and management.

Genetic testing increases the likelihood of a diagnosis of familial hypercholesterolaemia among people referred to lipid clinics: Danish national study

BACKGROUND AND AIMS

It is unclear to what extent genetic testing improves the ability to diagnose familial hypercholesterolaemia (FH). We investigated the percentage with FH among individuals referred to Danish lipid clinics, and evaluated the impact of genetic testing for a diagnosis of FH.

METHODS

From September 2020 through November 2021, all patients referred for possible FH to one of the 15 Danish lipid clinics were invited for study participation and >97% (n = 1488) accepted. The Dutch Lipid Clinical Network criteria were used to diagnose clinical FH. The decision of genetic testing for FH was based on local practice.

RESULTS

A total of 1243 individuals were referred, of whom 25.9% were diagnosed with genetic and/or clinical FH. In individuals genetically tested (n = 705), 21.7% had probable or definite clinical FH before testing, a percentage that increased to 36.9% after genetic testing. In individuals with unlikely and possible FH before genetic testing, 24.4% and 19.0%, respectively, had a causative pathogenic variant.

CONCLUSIONS

In a Danish nationwide study, genetic testing increased a diagnosis of FH from 22% to 37% in patients referred with hypercholesterolaemia suspected of having FH. Importantly, approximately 20% with unlikely or possible FH, who without genetic testing would not have been considered having FH (and family screening would not have been undertaken), had a pathogenic FH variant. We therefore recommend a more widespread use of genetic testing for evaluation of a possible FH diagnosis and potential cascade screening.

Risk factors for cardiovascular events in patients with heterozygous familial hypercholesterolaemia: protocol for a systematic review

INTRODUCTION

Heterozygous familial hypercholesterolaemia (heFH) is the most common monogenic cause of premature atherosclerotic cardiovascular disease. The precise diagnosis of heFH is established by genetic testing. This systematic review will investigate the risk factors that predict cardiovascular events in patients with a genetic diagnosis of heFH.

METHODS AND ANALYSIS

Our literature search will cover publications from database inception until June 2023. We will undertake a search of CINAHL (trial), clinicalKey, Cochrane Library, DynaMed, Embase, Espacenet, Experiments (trial), Fisterra, ÍnDICEs CSIC, LILACS, LISTA, Medline, Micromedex, NEJM Resident 360, OpenDissertations, PEDro, Trip Database, PubPsych, Scopus, TESEO, UpToDate, Web of Science and the grey literature for eligible studies. We will screen the title, abstract and full-text papers for potential inclusion and assess the risk of bias. We will employ the Cochrane tool for randomised controlled trials and non-randomised clinical studies and the Newcastle-Ottawa Scale for assessing the risk of bias in observational studies. We will include full-text peer-reviewed publications, reports of a cohort/registry, case-control and cross-sectional studies, case report/series and surveys related to adults (≥18 years of age) with a genetic diagnostic heFH. The language of the searched studies will be restricted to English or Spanish. The Grading of Recommendations, Assessment, Development and Evaluation approach will be used to assess the quality of the evidence. Based on the data available, the authors will determine whether the data can be pooled in meta-analyses.

ETHICS AND DISSEMINATION

All data will be extracted from published literature. Hence, ethical approval and patient informed consent are not required. The findings of the systematic review will be submitted for publication in a peer-reviewed journal and presentation at international conferences.

PROSPERO REGISTRATION NUMBER

CRD42022304273.

Australian Atherosclerosis Society Position Statement on Lipoprotein(a): Clinical and Implementation Recommendations

This position statement provides guidance to cardiologists and related specialists on the management of adult patients with elevated lipoprotein(a) [Lp(a)]. Elevated Lp(a) is an independent and causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). While circulating Lp(a) levels are largely determined by ancestry, they are also influenced by ethnicity, hormones, renal function, and acute inflammatory events, such that measurement should be done after accounting for these factors. Further, circulating Lp(a) concentrations should be estimated using an apo(a)-isoform independent assay that employs appropriate calibrators and reports the results in molar units (nmol/L). Selective screening strategies of high-risk patients are recommended, but universal screening of the population is currently not advised. Testing for elevated Lp(a) is recommended in all patients with premature ASCVD and those considered to be at intermediate-to-high risk of ASCVD. Elevated Lp(a) should be employed to assess and stratify risk and to enable a decision on initiation or intensification of preventative treatments, such as cholesterol lowering therapy. In adult patients with elevated Lp(a) at intermediate-to-high risk of ASCVD, absolute risk should be reduced by addressing all modifiable behavioural, lifestyle, psychosocial and clinical risk factors, including maximising cholesterol-lowering with statin and ezetimibe and, where appropriate, PCSK9 inhibitors. Apheresis should be considered in patients with progressive ASCVD. New ribonucleic acid (RNA)-based therapies which directly lower Lp(a) are undergoing clinical trials.

Persistence with long-term PCSK9 inhibitor treatment and its effectiveness in familial hypercholesterolaemia: data from the SAFEHEART study

AIMS

Most heterozygous familial hypercholesterolaemia (FH) patients require intensive lipid-lowering therapy (LLT) including PCSK9 inhibitors (PCSK9is) to reach current low-density lipoprotein cholesterol (LDL-C) goals. Persistence with chronic treatment is important to reduce the burden of atherosclerotic cardiovascular disease. We analysed persistence, efficacy, and impact on quality of life (QoL) of PCSK9i in FH patients in clinical practice setting.

METHODS AND RESULTS

Spanish Familial Hypercholesterolaemia Cohort Study (SAFEHEART) is an open, prospective study in genetically defined FH patients in Spain. Patients ≥18 years of age (n = 696, 46% females) on stable LLT treated with PCSK9i were analysed. Median LDL-C at starting PCSK9i was 145 mg/dL [interquartile range (IQR), 123-177], 3.8 mmol/L (IQR 3.2-4.6). After a median follow up of 3.7 years (IQR 2.3-4.8), 27 patients (4%) discontinued PCSK9i treatment: 5 temporarily (0.7%) and 22 permanently (3.2%). Persistence with PCSK9i was 96.1% in the whole period. Median LDL-C levels and % LDL-C reduction attained after 1 year of treatment and in the last follow-up visit were 63 mg/dL (IQR 43-88), 1.6 mmol/L (IQR 1.1-2.23); 61 mg/dL (IQR 44-82), 1.6 mmol/L (IQR 1.1-2.1); 57.6% (IQR 39.5-69); and 58% (IQR 44-68), respectively. 2016 and 2019 ESC/EAS LDL-C goals were attained by 77 and 48% of patients, respectively, at the last follow-up visit (P < 0.001). Mean QoL score increased slightly in the first year and remained stable.

CONCLUSION

Long-term persistence with PCSK9i in FH patients is very high, with a good QoL. Effectiveness in LDL-C reduction and LDL-C goal achievement dramatically improved with PCSK9i in this high-risk population in clinical practice setting.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02693548.

Maternal Inheritance of Familial Hypercholesterolemia Gene Mutation Predisposes to Coronary Atherosclerosis as Assessed by Calcium Score in Adulthood

BACKGROUND

Animal studies have demonstrated that fetal exposure to high maternal cholesterol levels during pregnancy predisposes to aortic atheroma in the offspring. In humans, little is known about the consequences of this exposure on the development of atherosclerotic cardiovascular disease later in life. We wanted to assess whether maternal/paternal inheritance of familial hypercholesterolemia (FH) gene mutation could be associated with subclinical coronary atherosclerosis.

METHODS

We retrospectively included 1350 patients, followed in the French registry of FH, with a documented genetic diagnosis. We selected 556 age- and sex-matched pair of patients based on the sex of the parents who transmitted the FH gene mutation, free of coronary cardiovascular event, and with a subclinical coronary atherosclerosis evaluation assessed using coronary artery calcium (CAC) score. We performed univariate and multivariate analysis to assess the individual effect of parental inheritance of the FH gene mutation on the CAC score.

RESULTS

In the whole population, patients with maternal inheritance of FH gene mutation (n=639) less frequently had a family history of premature cardiovascular events (27.7% versus 45%, P<0.0001) and were 2 years older (46.9±16.8 versus 44.7±15.9 years old, P=0.02) than those with paternal inheritance (n=711). There was no difference in the prevalence of cardiovascular events between the two groups. In the matched subgroup, maternal inheritance was significantly associated with an increase in CAC score value by 86% (95% CI, 23%-170%; P=0.003), a 1.81-fold risk of having a CAC score ≥100 Agatston units (95% CI, 1.06-3.11; P=0.03), and a 2.72-fold risk of having a CAC score ≥400 Agatston units (95% CI, 1.39-5.51; P=0.004) when compared with paternal inheritance in multivariate analysis.

CONCLUSIONS

Maternal inheritance of FH gene mutation was associated with more severe subclinical coronary atherosclerosis assessed by CAC score and may be considered as a potential cardiovascular risk factor.

Hepatic fat as a novel marker for high-risk coronary atherosclerotic plaque features in familial hypercholesterolaemia

BACKGROUND & AIMS

Hepatic steatosis has been associated with increased risk of coronary artery disease. Individuals with familial hypercholesterolaemia have accelerated but variable progression of coronary artery disease. We investigated whether hepatic steatosis is associated with novel coronary atherosclerosis biomarkers in adults with heterozygous familial hypercholesterolaemia, using comprehensive coronary computed tomographic angiography.

METHODS

We conducted a cross-sectional study of 213 asymptomatic patients with familial hypercholesterolaemia (median age 54.0 years, 59 % female) who underwent coronary computed tomographic angiography for cardiovascular risk assessment in an outpatient clinic. High-risk plaque features, plaque volume and pericoronary adipose tissue attenuation were assessed. From concurrently captured upper abdominal images, severity of hepatic steatosis was computed, as liver minus spleen computed tomography attenuation and stratified into quartiles.

RESULTS

Of 213 familial hypercholesterolaemia patients, 59 % had coronary artery calcium, 36 % obstructive coronary artery disease (≥50 % stenosis) and 77 % high-risk plaque features. Increasing hepatic steatosis was associated with higher calcium scores, more high-risk plaque features and presence of obstructive coronary artery disease. Hepatic steatosis was associated with the presence of high-risk plaque features (OR: 1.48; 95 % CI: 1.09-2.00; p = 0.01), particularly in the proximal coronary segments (OR: 1.52; 95 % CI: 1.18-1.96; p = 0.001). Associations persisted on multivariable logistic regression analysis adjusting for cardiometabolic factors, obstructive coronary artery disease and calcium score. Hepatic steatosis was associated with higher plaque volumes (Q4: 499 mm³ vs Q1: 414 mm³, p = 0.02), involving mainly low attenuation and noncalcified plaques (both p = 0.03). No differences in pericoronary adipose tissue attenuation were observed.

CONCLUSIONS

Hepatic steatosis is associated with multiple indices of advanced coronary atherosclerosis in familial hypercholesterolaemia patients, particularly high-risk plaque features, independent of conventional cardiovascular risk factors and markers. This may involve specific mechanisms related to hepatic steatosis.

CLINICAL TRIAL NUMBER

N/A.

Metabolomic Approach to Screening Homozygotes in Chinese Patients with Severe Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a rare inborn-errors-of-metabolism disorder characterized by devastatingly elevated low-density lipoprotein cholesterol (LDL-C) and premature cardiovascular disease. The gold standard for screening and diagnosing HoFH is genetic testing. In China, it is expensive and is always recommended for the most likely HoFH subjects with aggressive LDL-C phenotype. However, the LDL-C levels of HoFH patients and a substantial proportion of heterozygous FH (HeFH) patients overlapped considerably. Here, we performed a cost-effective metabolomic profiling on genetically diagnosed HoFH (n = 69) and HeFH patients (n = 101) with overlapping LDL-C levels, aiming to discovery a unique metabolic pattern for screening homozygotes in patients with severe FH. We demonstrated a differential serum metabolome profile in HoFH patients compared to HeFH patients. Twenty-one metabolomic alterations showed independent capability in differentiating HoFH from severe HeFH. The combined model based on seven identified metabolites yielded a corrected diagnosis in 91.3% of HoFH cases with an area under the curve value of 0.939. Collectively, this study demonstrated that metabolomic profiling serves as a useful and economical approach to preselecting homozygotes in FH patients with severe hypercholesterolemia and may help clinicians to conduct selective genetic confirmation testing and familial cascade screening.

The Inherited Hypercholesterolemias

Inherited hypercholesterolemias include monogenic and polygenic disorders, which can be very rare (eg, cerebrotendinous xanthomatosis (CTX)) or relatively common (eg, familial combined hyperlipidemia [FCH]). In this review, we discuss familial hypercholesterolemia (FH), FH-mimics (eg, polygenic hypercholesterolemia [PH], FCH, sitosterolemia), and other inherited forms of hypercholesterolemia (eg, hyper-lipoprotein(a) levels [hyper-Lp(a)]). The prevalence, genetics, and management of inherited hypercholesterolemias are described and selected guidelines summarized.

Lipoprotein(a) in atherosclerotic cardiovascular disease and aortic stenosis: a European Atherosclerosis Society consensus statement

This 2022 European Atherosclerosis Society lipoprotein(a) [Lp(a)] consensus statement updates evidence for the role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis, provides clinical guidance for testing and treating elevated Lp(a) levels, and considers its inclusion in global risk estimation. Epidemiologic and genetic studies involving hundreds of thousands of individuals strongly support a causal and continuous association between Lp(a) concentration and cardiovascular outcomes in different ethnicities; elevated Lp(a) is a risk factor even at very low levels of low-density lipoprotein cholesterol. High Lp(a) is associated with both microcalcification and macrocalcification of the aortic valve. Current findings do not support Lp(a) as a risk factor for venous thrombotic events and impaired fibrinolysis. Very low Lp(a) levels may associate with increased risk of diabetes mellitus meriting further study. Lp(a) has pro-inflammatory and pro-atherosclerotic properties, which may partly relate to the oxidized phospholipids carried by Lp(a). This panel recommends testing Lp(a) concentration at least once in adults; cascade testing has potential value in familial hypercholesterolaemia, or with family or personal history of (very) high Lp(a) or premature ASCVD. Without specific Lp(a)-lowering therapies, early intensive risk factor management is recommended, targeted according to global cardiovascular risk and Lp(a) level. Lipoprotein apheresis is an option for very high Lp(a) with progressive cardiovascular disease despite optimal management of risk factors. In conclusion, this statement reinforces evidence for Lp(a) as a causal risk factor for cardiovascular outcomes. Trials of specific Lp(a)-lowering treatments are critical to confirm clinical benefit for cardiovascular disease and aortic valve stenosis.

Developing a Hybrid Risk Assessment Tool for Familial Hypercholesterolemia: A Machine Learning Study of Chinese Arteriosclerotic Cardiovascular Disease Patients

Background

Familial hypercholesterolemia (FH) is an autosomal-dominant genetic disorder with a high risk of premature arteriosclerotic cardiovascular disease (ASCVD). There are many alternative risk assessment tools, for example, DLCN, although their sensitivity and specificity vary among specific populations. We aimed to assess the risk discovery performance of a hybrid model consisting of existing FH risk assessment tools and machine learning (ML) methods, based on the Chinese patients with ASCVD.

Materials and Methods

In total, 5,597 primary patients with ASCVD were assessed for FH risk using 11 tools. The three best performing tools were hybridized through a voting strategy. ML models were set according to hybrid results to create a hybrid FH risk assessment tool (HFHRAT). PDP and ICE were adopted to interpret black box features.

Results

After hybridizing the mDLCN, Taiwan criteria, and DLCN, the HFHRAT was taken as a stacking ensemble method (AUC_class[94.85 ± 0.47], AUC_prob[98.66 ± 0.27]). The interpretation of HFHRAT suggests that patients aged <75 years with LDL-c >4 mmol/L were more likely to be at risk of developing FH.

Conclusion

The HFHRAT has provided a median of the three tools, which could reduce the false-negative rate associated with existing tools and prevent the development of atherosclerosis. The hybrid tool could satisfy the need for a risk assessment tool for specific populations.

Integrated guidance to enhance the care of children and adolescents with familial hypercholesterolaemia: Practical advice for the community clinician

Familial hypercholesterolaemia (FH) is a highly penetrant monogenic disorder present from birth that markedly elevates plasma low-density lipoprotein (LDL)-cholesterol (LDL-C) concentration and, if untreated, leads to premature atherosclerosis and coronary artery disease (CAD). At a prevalence of 1:250 individuals, with over 90% undiagnosed, recent estimates suggest that there are approximately 22 000 children and adolescents with FH in Australia and New Zealand. However, the overwhelming majority remain undetected and inadequately treated until adulthood or after their first cardiac event. The guidance in this paper aims to increase awareness about paediatric FH and provide practical advice for the diagnosis and management of FH in children and adolescents. Recommendations are given on the detection, diagnosis, assessment and management of FH in children and adolescents. Recommendations are also made on genetic testing, including counselling and the potential for universal screening programmes. Practical guidance on management includes treatment of non-cholesterol risk factors, and safe and appropriate use of LDL-C lowering therapies, including statins, ezetimibe, PCSK9 inhibitors and lipoprotein apheresis. Models of care for FH need to be adapted to local and regional health care needs and available resources. Targeting the detection of FH as a priority in children and young adults has the potential to alter the natural history of atherosclerotic cardiovascular disease and recognise the promise of early detection for improving long-term health outcomes. A comprehensive implementation strategy, informed by further research, including assessments of cost-benefit, will be required to ensure that this new guidance benefits all families with or at risk of FH.

Predicting resilience in heterozygous familial hypercholesterolaemia: A cohort study of octogenarian patients

Defining patients with familial hypercholesterolemia (FH) destined not to develop clinical atherosclerotic cardiovascular disease (ASCVD) has significant implications for precision and discovery medicine. We investigated the predictors of resilience to ASCVD in a cohort of 248 octogenarian patients with FH enrolled in the SAFEHEART study. Median age at the time of analysis was 84.7 years (82.3-88.1) and 83.6 years (81.9-86.4) in the octogenarian resilient FH (OR-FH) and octogenarian controls non-resilient FH (OCNoR-FH) groups, respectively (p=0.073); 92 (80.0%) and 68 (51.1%) patients were female in the first compared with the second group (p<0.001). Multivariate logistic regression showed that a low 10-year score in SAFEHEART-Risk Equation was the only independent predictor of OR-FH. Application of this simple and validated risk equation may potentially be useful for predicting patients ultra-resilient to the ASCVD sequelae of FH who may require less intensive use of healthcare resources.

The role of hepatic Surf4 in lipoprotein metabolism and the development of atherosclerosis in apoE-/- mice

Elevated plasma levels of low-density lipoprotein-C (LDL-C) increase the risk of atherosclerotic cardiovascular disease. Circulating LDL is derived from very low-density lipoprotein (VLDL) metabolism and cleared by LDL receptor (LDLR). We have previously demonstrated that cargo receptor Surfeit 4 (Surf4) mediates VLDL secretion. Inhibition of hepatic Surf4 impairs VLDL secretion, significantly reduces plasma LDL-C levels, and markedly mitigates the development of atherosclerosis in LDLR knockout (Ldlr^-/-) mice. Here, we investigated the role of Surf4 in lipoprotein metabolism and the development of atherosclerosis in another commonly used mouse model of atherosclerosis, apolipoprotein E knockout (apoE^-/-) mice. Adeno-associated viral shRNA was used to silence Surf4 expression mainly in the liver of apoE^-/- mice. In apoE^-/- mice fed a regular chow diet, knockdown of Surf4 expression significantly reduced triglyceride secretion and plasma levels of non-HDL cholesterol and triglycerides without causing hepatic lipid accumulation or liver damage. When Surf4 was knocked down in apoE^-/- mice fed the Western-type diet, we observed a significant reduction in plasma levels of non-HDL cholesterol, but not triglycerides. Knockdown of Surf4 did not increase hepatic cholesterol and triglyceride levels or cause liver damage, but significantly diminished atherosclerosis lesions. Therefore, our findings indicate the potential of hepatic Surf4 inhibition as a novel therapeutic strategy to reduce the risk of atherosclerotic cardiovascular disease.

Familial Hypercholesterolemia and Elevated Lipoprotein(a): Cascade Testing and Other Implications for Contextual Models of Care

Elevated lipoprotein(a) [Lp(a)], a predominantly genetic disorder, is a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valvular disease, particularly in patients with familial hypercholesterolemia (FH), a Tier I genomic condition. The combination from birth of the cumulative exposure to elevated plasma concentrations of both Lp(a) and low-density lipoprotein is particularly detrimental and explains the enhanced morbidity and mortality risk observed in patients with both conditions. An excellent opportunity to identify at-risk patients with hyper-Lp(a) at increased risk of ASCVD is to test for hyper-Lp(a) during cascade testing for FH. With probands having FH and hyper-Lp(a), the yield of detection of hyper-Lp(a) is 1 individual for every 2.1-2.4 relatives tested, whereas the yield of detection of both conditions is 1 individual for every 3-3.4 relatives tested. In this article, we discuss the incorporation of assessment of Lp(a) in the cascade testing in FH as a feasible and crucial part of models of care for FH. We also propose a simple management tool to help physicians identify and manage elevated Lp(a) in FH, with implications for the care of Lp(a) beyond FH, noting that the clinical use of RNA therapeutics for specifically targeting the overproduction of Lp(a) in at risk patients is still under investigation.

Clinical decision support for familial hypercholesterolemia (CDS-FH): Rationale and design of a cluster randomized trial in primary care

BACKGROUND

Familial hypercholesterolemia (FH) is an underdiagnosed and undertreated genetic disorder with high risk of premature atherosclerotic cardiovascular disease and death. Clinical decision support (CDS) systems have the potential to aid in the identification and management of patients with FH. Prior studies using computer-based systems to screen patients for FH have shown promising results, but there has been no randomized controlled trial conducted. The aim of the current cluster randomized study is to evaluate if a CDS can increase the identification of FH.

METHODS

We have developed a CDS integrated in the electronic health records that will be activated in patients with elevated cholesterol levels (total cholesterol >8 mmol/L or low-density lipoprotein-cholesterol >5.5 mmol/L, adjusted for age, ongoing lipid lowering therapy and presence of premature coronary artery disease) at increased risk for FH. When activated, the CDS will urge the physician to send an automatically generated referral to the local lipid clinic for further evaluation. To evaluate the effects of the CDS, all primary care clinics will be cluster randomized 1:1 to either CDS intervention or standard care in a Swedish region with almost 500,000 inhabitants. The primary endpoint will be the number of patients diagnosed with FH at 30 months. Resource use and long-term health consequences will be estimated to assess the cost-effectiveness of the intervention.

CONCLUSION

Despite increasing awareness of FH, the condition remains underdiagnosed and undertreated. The present study will investigate whether a CDS can increase the number of patients being diagnosed with FH.

A Selective Screening Strategy Performed in Pre-School Children and Siblings to Detect Familial Hypercholesterolemia

(1) Background: Familial hypercholesterolemia (FH), a most common genetic disorder, is underdiagnosed and untreated, especially in children. Individuals with heterozygous familial hypercholesterolemia mostly present without clinical symptoms and are not informed about their high risk for myocardial infarction. Early diagnosis and treatment can prevent premature atherosclerosis and cardiovascular events in patients with FH. The aim was to evaluate the detection rate of pre-school children with FH at school doctor visits in Vienna and, moreover, to examine the frequency of FH identified in the children’s siblings by this type of screening. (2) Methods: The selective FH- screening was implemented at the school enrolment examinations in the public primary schools of Vienna. The study period included the school years starting in 2017 to 2020. FH was suspected if a questionnaire on hypercholesterolemia, or cardiovascular events in the family history or on the presence of xanthomas or xanthelasma, was positive. Subsequently, lipid testing was performed on pre-school children and their siblings and elevated lipid screening was defined as either positive by LDL-C ≥ 160 mg/dL and/or non-HDL-C ≥ 190 mg/dL or as borderline by LDL-C ≥ 130 mg/dL and/or non-HDL-C ≥ 160 mg/dL. (3) Results: 66,108 pre-school children participated in the school enrolment examination in 868 public elementary schools in Vienna. In 512 (4%) children, the questionnaire caused suspicion of FH. 344 families agreed their participation in the study. Out of 344 (52% male) tested pre-school children, 20 individuals (40% male) had elevated blood lipid levels with a mean LDL-C of 155 ± 29 mg/dL and a non-HDL-C of 180 ± 24 mg/dL. Out of 291 (44% male) tested siblings, 17 individuals (41% male) showed elevated lipids with a mean LDL-C of 144 ± 19 mg/dL, and a non-HDL-C of 174 ± 19 mg/dL. (4) Conclusions: Screening is the key for early diagnosis and treatment of FH. We have implemented a pre-school screening strategy in cooperation with school physicians. We could identify 20 pre-school children and 17 siblings with an elevated lipid screening test. Full implementation of FH-screening in the pre-school examination visits in Vienna would help to detect high-risk children.

New Therapies for Primary Hyperlipidemia

Primary hyperlipidemias include a heterogeneous set of monogenic and polygenic conditions characterized by a strong family aggregation, severe forms of hypercholesterolemia and/or hypertriglyceridemia, appearance early on life, and a high risk of cardiovascular events and/or recurrent pancreatitis. In real life, a small proportion of the primary hyperlipidemia cases is recognized and treated properly. Our goal is to present an update of current and upcoming therapies for patients with primary hyperlipidemia. Recently, new lipid-lowering medications have obtained authorization from the U.S. Food and Drug Administration and the European Medicines Agency. These drugs target metabolic pathways, including (adenosine 5'-triphosphates)-citrate lyase (bempedoic acid), proprotein convertase subtilisin/kexin 9 (inclisiran), apolipoprotein CIII (volanesorsen), and angiopoietin-like 3 (volanesorsen), that have additive effects with the actions of the currently available therapies (i.e., statins, ezetimibe or fibrates). We discuss the potential clinical indications for the novel medications. To conclude, the addition of these new medications to the therapeutic options for primary hyperlipidemia patients may increase the likelihood of achieving the treatment targets. Also, it could be a safer alternative for patients with side effects for the currently available drugs.

Collaborative Approach to Reach Everyone with Familial Hypercholesterolemia: CARE-FH Protocol

The Collaborative Approach to Reach Everyone with Familial Hypercholesterolemia (CARE-FH) study aims to improve diagnostic evaluation rates for FH at Geisinger, an integrated health delivery system. This clinical trial relies upon implementation science to transition the initial evaluation for FH into primary care, attempting to identify individuals prior to the onset of atherosclerotic cardiovascular disease events. The protocol for the CARE-FH study of this paper is available online. The first phase of the project focuses on trial design, including the development of implementation strategies to deploy evidence-based guidelines. The second phase will study the intervention, rolled out regionally to internal medicine, community medicine, and pediatric care clinicians using a stepped-wedge design, and analyzing data on diagnostic evaluation rates, and implementation, service, and health outcomes.

Familial Hypercholesterolemia and Lipoprotein(a): Two Partners in Crime?

PURPOSE OF REVIEW

Familial hypercholesterolemia is a high cardiovascular risk disorder. We will review the role of lipoprotein(a) in cardiovascular risk and in aortic valve stenosis in familial hypercholesterolemia, as well as its association with their phenotype, and strategies to identify this high-risk population.

RECENT FINDINGS

Patients with familial hypercholesterolemia have higher lipoprotein(a) levels mainly due to an increased frequency of LPA variants, and the cardiovascular risk is increased twofolds when both conditions coexist. Also, an increased risk for aortic valve stenosis and valve replacement has been observed with high lipoprotein(a) levels. Assessment of lipoprotein(a) during the cascade screening for familial hypercholesterolemia is a good opportunity to identify this high-risk population. High cardiovascular risk in familial hypercholesterolemia is increased even more when lipoprotein(a) is also elevated. Measurement of lipoprotein(a) in these patients is crucial to identify those subjects who need to intensify LDL-cholesterol reduction pending availability of lipoprotein(a)-specific treatments.

Association of dietary patterns and components with atherosclerosis risk biomarkers in familial hypercholesterolemia

PURPOSE OF REVIEW

Familial hypercholesterolemia (FH) is a relatively common genetic disorder associated with elevated atherosclerotic risk. Dietary interventions can modulate processes associated with cardiovascular risk and potentiate the impact of pharmacological lipid-lowering therapies. This review evaluates recent findings of dietary patterns and their components on risk biomarkers in people with FH.

RECENT FINDINGS

Diets lower in saturated fatty acids (SFA) may reduce low-density lipoprotein-cholesterol (LDL-C); however, their effects seem to be modest. A Mediterranean style diet apparently exerts more robust effects on plasma LDL-C, apolipoprotein B and C reactive protein concentrations than one restricted in SFA. Supplementation of plant sterols and stanols reduces LDL-C especially in children with FH. Caloric restricted diets may reduce weight and improve triglyceride levels in individuals with FH and excess body weight.

SUMMARY

Despite the strong impact of genetic variants, dietary patterns mostly low in SFA and especially the Mediterranean diet may influence risk biomarkers in FH. However, most available studies are limited by cross-sectional design, small number of study subjects and short-term follow-ups. Robust interventional studies are necessary to test the impact of dietary patterns in people with FH.

Apolipoproteins in vascular biology and atherosclerotic disease

Apolipoproteins are important structural components of plasma lipoproteins that influence vascular biology and atherosclerotic disease pathophysiology by regulating lipoprotein metabolism. Clinically important apolipoproteins related to lipid metabolism and atherogenesis include apolipoprotein B-100, apolipoprotein B-48, apolipoprotein A-I, apolipoprotein C-II, apolipoprotein C-III, apolipoprotein E and apolipoprotein(a). Apolipoprotein B-100 is the major structural component of VLDL, IDL, LDL and lipoprotein(a). Apolipoprotein B-48 is a truncated isoform of apolipoprotein B-100 that forms the backbone of chylomicrons. Apolipoprotein A-I provides the scaffolding for lipidation of HDL and has an important role in reverse cholesterol transport. Apolipoproteins C-II, apolipoprotein C-III and apolipoprotein E are involved in triglyceride-rich lipoprotein metabolism. Apolipoprotein(a) covalently binds to apolipoprotein B-100 to form lipoprotein(a). In this Review, we discuss the mechanisms by which these apolipoproteins regulate lipoprotein metabolism and thereby influence vascular biology and atherosclerotic disease. Advances in the understanding of apolipoprotein biology and their translation into therapeutic agents to reduce the risk of cardiovascular disease are also highlighted.

Myocardial fibrosis assessed by magnetic resonance imaging in asymptomatic heterozygous familial hypercholesterolemia: the cholcoeur study

BACKGROUND

Familial Hypercholesterolemia (FH) is an underdiagnosed condition with an increased cardiovascular risk. It is unknown whether lipid accumulation plays a role in structural myocardial changes. Cardiovascular Magnetic Resonance (CMR) is the reference technique for the morpho-functional evaluation of heart chambers through cine sequences and for myocardial tissue characterization through late gadolinium enhancement (LGE) and T1 mapping images. We aimed to assess the prevalence of myocardial fibrosis in FH patients.

METHODS

Seventy-two asymptomatic subjects with genetically confirmed FH (mean age 49·24, range 40 to 60 years) were prospectively recruited along with 31 controls without dyslipidaemia matched for age, sex, BMI, and other cardiovascular risk factors. All underwent CMR including cine, LGE, pre- and post-contrast T1 mapping. Extracellular volume (ECV) and enhancement rate of the myocardium (ERM = difference between pre- and post-contrast myocardial T1, normalized by pre-contrast myocardial T1) were calculated.

FINDINGS

Five FH patients and none of the controls had intramyocardial LGE (p= 0·188). While no changes in Native T1 and ECV were found, post-contrast T1 was significantly lower (430·6 ± 55ms vs. 476·1 ± 43ms, p<0·001) and ERM was higher (57·44± 5·99 % vs 53·04±4·88, p=0·005) in HeFH patients compared to controls. Moreover, low post-contrast T1 was independently associated with the presence of xanthoma (HR 5·221 [1·04-26·28], p= 0·045). A composite score combining the presence of LGE, high native T1 and high ERM (defined as ≥ mean ± 1·5 SD) was found in 20·8% of the HeFH patients vs. 0% in controls (p<0·000, after adjustment for main confounders).

INTERPRETATION

CMR revealed early changes in myocardial tissue characteristics in HeFH patients, that should foster further work to better understand and prevent the underlying pathophysiological processes.

A resilient type of familial hypercholesterolaemia: case-control follow-up of genetically characterized older patients in the SAFEHEART cohort

AIMS 

Knowledge of the features of patients with familial hypercholesterolaemia (FH) who are protected from atherosclerotic cardiovascular disease (ASCVD) is important for the clinical and prognostic care of this apparently high-risk condition. Our aim was to investigate the determinant and characteristics of patients with FH who are protected from ASCVD and have normal life expectancy, so-called 'resilient' FH (R-FH).

METHODS AND RESULTS 

Spanish Familial Hypercholesterolaemia cohort study (SAFEHEART) is an open, multicentre, nation-wide, long-term prospective cohort study in genetically defined patients with heterozygous FH in Spain. Patients in the registry who at the time of analysis were at least 65 years or those who would have reached that age had they not died from an ASCVD event were analysed as a case-control study. Resilient FH was defined as the presence of a pathogenic mutation causative of FH in a patient aged ≥65 years without clinical ASCVD. Nine hundred and thirty registrants with FH met the study criteria. A defective low-density lipoprotein (LDL)-receptor mutation, higher plasma level of high-density lipoprotein cholesterol (HDL-C), younger age, female gender, absence of hypertension, and lower plasma lipoprotein (a) [Lp(a)] concentration were independently predictive of R-FH. In a second model, higher levels of HDL-C and lower 10-year score in SAFEHEART-RE were also independently predictive of R-FH.

CONCLUSION 

Resilient FH may be typified as being female and having a defective LDL-receptor mutation, higher levels of plasma HDL-C, lower levels of Lp(a), and an absence of hypertension. The implications of this type of FH for clinical practice guidelines and the value for service design and optional care of FH remains to be established.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02693548.

Splice correction therapies for familial hypercholesterolemic patients with low-density lipoprotein receptor mutations

PURPOSE OF REVIEW

Antisense oligomers (ASOs) have been available for decades: however, only recently have these molecules been applied clinically. This review aims to discuss the possible development of antisense-mediated splice correction therapies as precision medicines for familial hypercholesterolemic patients carrying mutations that compromise normal splicing of the low-density lipoprotein receptor (LDLR) gene transcript.

RECENT FINDINGS

Three antisense drugs are currently being assessed in ongoing clinical trials for dyslipidemias, aiming to lower the plasma concentrations of lipoproteins that lead to end-organ damage, principally coronary artery disease. Although a handful of drugs may be applicable to many patients with familial hypercholesterolemia (FH), mutation-specific personalised antisense drugs may be even more effective in selected patients. Currently, there is no therapy that effectively addresses mutations in the LDLR, the major cause of FH. Many mutations in the LDLR that disrupt normal pre-mRNA processing could be applicable to splice correction therapy to restore receptor activity.

SUMMARY

Precision medicine could provide long-term economic and social benefits if they can be implemented effectively and sustainably. Many mutations found in the LDLR gene could be amendable to therapeutic splice correction and we should consider developing a therapeutic ASO platform for these mutations.

Regulation of PCSK9 Expression and Function: Mechanisms and Therapeutic Implications

Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes degradation of low-density lipoprotein receptor (LDLR) and plays a central role in regulating plasma levels of LDL cholesterol levels, lipoprotein(a) and triglyceride-rich lipoproteins, increasing the risk of cardiovascular disease. Additionally, PCSK9 promotes degradation of major histocompatibility protein class I and reduces intratumoral infiltration of cytotoxic T cells. Inhibition of PCSK9 increases expression of LDLR, thereby reducing plasma levels of lipoproteins and the risk of cardiovascular disease. PCSK9 inhibition also increases cell surface levels of major histocompatibility protein class I in cancer cells and suppresses tumor growth. Therefore, PCSK9 plays a vital role in the pathogenesis of cardiovascular disease and cancer, the top two causes of morbidity and mortality worldwide. Monoclonal anti-PCSK9 antibody-based therapy is currently the only available treatment that can effectively reduce plasma LDL-C levels and suppress tumor growth. However, high expenses limit their widespread use. PCSK9 promotes lysosomal degradation of its substrates, but the detailed molecular mechanism by which PCSK9 promotes degradation of its substrates is not completely understood, impeding the development of more cost-effective alternative strategies to inhibit PCSK9. Here, we review our current understanding of PCSK9 and focus on the regulation of its expression and functions.

Cascade testing for elevated lipoprotein(a) in relatives of probands with familial hypercholesterolaemia and elevated lipoprotein(a)

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) and elevated plasma lipoprotein(a) [Lp(a)] are inherited conditions independently associated with atherosclerotic cardiovascular disease. This study investigated the detection of new cases of elevated Lp(a) during cascade testing of relatives of probands with a definite diagnosis of FH and elevated Lp(a) (≥50 mg/dL).

METHODS

Relatives from 62 adult probands were tested for FH genetically and for elevated Lp(a) using an immunoassay. The prevalence and yield of new cases of FH with or without elevated Lp(a) among relatives and the association between the detection of elevated Lp(a) and the Lp(a) concentration of the probands were assessed.

RESULTS

Among 162 relatives tested (136 adults and 26 children), the prevalence of FH and elevated Lp(a) was 60.5% and 41.4%, respectively: FH alone was detected in 31.5%, elevated Lp(a) alone in 12.3%, FH with elevated Lp(a) in 29.0%, and neither disorder in 27.2% of the relatives. Cascade testing detected a new case of FH, elevated Lp(a) and FH with elevated Lp(a) for every 1.5, 2.1 and 3.0 relatives tested, respectively. The proportion of relatives detected with elevated Lp(a) was significantly higher when tested from probands with Lp(a) ≥100 mg/dL compared with those from probands with Lp(a) between 50 and 99 mg/dL (53% vs 34%, p = 0.018). The concordance between the detection of FH and elevated Lp(a) was 56.2% (kappa statistic 0.154), indicating a poor agreement.

CONCLUSIONS

A dual approach to cascade testing families for FH and high Lp(a) from appropriate probands can effectively identify not only new cases of FH, but also new cases of elevated Lp(a) with or without FH. The findings accord with the co-dominant and independent heritability of FH and Lp(a).

Population genomic screening of young adults for familial hypercholesterolaemia: a cost-effectiveness analysis

AIMS

The aim of this study was to assess the impact and cost-effectiveness of offering population genomic screening to all young adults in Australia to detect heterozygous familial hypercholesterolaemia (FH).

METHODS AND RESULTS

We designed a decision analytic Markov model to compare the current standard of care for heterozygous FH diagnosis in Australia (opportunistic cholesterol screening and genetic cascade testing) with the alternate strategy of population genomic screening of adults aged 18-40 years to detect pathogenic variants in the LDLR/APOB/PCSK9 genes. We used a validated cost-adaptation method to adapt findings to eight high-income countries. The model captured coronary heart disease (CHD) morbidity/mortality over a lifetime horizon, from healthcare and societal perspectives. Risk of CHD, treatment effects, prevalence, and healthcare costs were estimated from published studies. Outcomes included quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratio (ICER), discounted 5% annually. Sensitivity analyses were undertaken to explore the impact of key input parameters on the robustness of the model. Over the lifetime of the population (4 167 768 men; 4 129 961 women), the model estimated a gain of 33 488years of life lived and 51 790 QALYs due to CHD prevention. Population genomic screening for FH would be cost-effective from a healthcare perspective if the per-test cost was ≤AU$250, yielding an ICER of <AU$28 000 per QALY gained. From a societal perspective, population genomic screening would be cost-saving. ICERs from societal perspective remained cost-saving after adaptation to other countries.

CONCLUSION

Based on our model, offering population genomic screening to all young adults for FH could be cost-effective, at testing costs that are feasible.

Global perspective of familial hypercholesterolaemia: a cross-sectional study from the EAS Familial Hypercholesterolaemia Studies Collaboration (FHSC)

BACKGROUND

The European Atherosclerosis Society Familial Hypercholesterolaemia Studies Collaboration (FHSC) global registry provides a platform for the global surveillance of familial hypercholesterolaemia through harmonisation and pooling of multinational data. In this study, we aimed to characterise the adult population with heterozygous familial hypercholesterolaemia and described how it is detected and managed globally.

METHODS

Using FHSC global registry data, we did a cross-sectional assessment of adults (aged 18 years or older) with a clinical or genetic diagnosis of probable or definite heterozygous familial hypercholesterolaemia at the time they were entered into the registries. Data were assessed overall and by WHO regions, sex, and index versus non-index cases.

FINDINGS

Of the 61 612 individuals in the registry, 42 167 adults (21 999 [53·6%] women) from 56 countries were included in the study. Of these, 31 798 (75·4%) were diagnosed with the Dutch Lipid Clinic Network criteria, and 35 490 (84·2%) were from the WHO region of Europe. Median age of participants at entry in the registry was 46·2 years (IQR 34·3-58·0); median age at diagnosis of familial hypercholesterolaemia was 44·4 years (32·5-56·5), with 40·2% of participants younger than 40 years when diagnosed. Prevalence of cardiovascular risk factors increased progressively with age and varied by WHO region. Prevalence of coronary disease was 17·4% (2·1% for stroke and 5·2% for peripheral artery disease), increasing with concentrations of untreated LDL cholesterol, and was about two times lower in women than in men. Among patients receiving lipid-lowering medications, 16 803 (81·1%) were receiving statins and 3691 (21·2%) were on combination therapy, with greater use of more potent lipid-lowering medication in men than in women. Median LDL cholesterol was 5·43 mmol/L (IQR 4·32-6·72) among patients not taking lipid-lowering medications and 4·23 mmol/L (3·20-5·66) among those taking them. Among patients taking lipid-lowering medications, 2·7% had LDL cholesterol lower than 1·8 mmol/L; the use of combination therapy, particularly with three drugs and with proprotein convertase subtilisin-kexin type 9 inhibitors, was associated with a higher proportion and greater odds of having LDL cholesterol lower than 1·8 mmol/L. Compared with index cases, patients who were non-index cases were younger, with lower LDL cholesterol and lower prevalence of cardiovascular risk factors and cardiovascular diseases (all p<0·001).

INTERPRETATION

Familial hypercholesterolaemia is diagnosed late. Guideline-recommended LDL cholesterol concentrations are infrequently achieved with single-drug therapy. Cardiovascular risk factors and presence of coronary disease were lower among non-index cases, who were diagnosed earlier. Earlier detection and greater use of combination therapies are required to reduce the global burden of familial hypercholesterolaemia.

FUNDING

Pfizer, Amgen, Merck Sharp & Dohme, Sanofi-Aventis, Daiichi Sankyo, and Regeneron.

Identification and Functional Characterization of a Low-Density Lipoprotein Receptor Gene Pathogenic Variant in Familial Hypercholesterolemia

We report a single-point variant of low-density lipoprotein receptor (LDLR) in a Chinese proband with a clinical diagnosis of familial hypercholesterolemia (FH) with a comprehensive functional analysis. Target exome capture-based next-generation sequencing was used for sequencing and identification of genomic variants in the LDLR gene. The expression, cellular location, and function of the mutant LDLR were analyzed. Sequencing of LDLR in FH patients indicated a point variant of single-base substitution (G < A) at a position of 2389 in the 16th exon, which led to a loss of the 16th exon in the LDLR messenger RNA. This genomic variant was found to cause exon 16 deletion in the mutant LDLR protein. Subsequent functional analyses showed that the mutant LDLR was retained in the Golgi apparatus and rarely expressed in the cellular membranes of HepG2 cells. Accordingly, the intake ability of HepG2 cells with the mutant LDLR was significantly reduced (P < 0.05). In conclusion, our results suggest that a mutant with a single-base substitution (c. 2389G > A) in the 16th exon of the LDLR gene was associated with miscleavage of messenger RNA and the retention of mutant LDLR in the Golgi apparatus, which revealed a pathogenic variant in LDLR underlying the pathogenesis of FH.