Diagnostic Yield and Clinical Utility of Sequencing Familial Hypercholesterolemia Genes in Patients With Severe Hypercholesterolemia

Genetics, Lifestyle, and Low-Density Lipoprotein Cholesterol in Young and Apparently Healthy Women

Background:

Atherosclerosis starts in childhood but low-density lipoprotein cholesterol (LDL-C), a causal risk factor, is mostly studied and dealt with when clinical events have occurred. Women are usually affected later in life than men and are underdiagnosed, undertreated, and understudied in cardiovascular trials and research. This study aims at a better understanding of lifestyle and genetic factors that affect LDL-C in young women.

Methods:

We randomly selected for every year of age 8 women with LDL-C ≤1st percentile (≤50 mg/dL) and 8 women with LDL-C ≥99th percentile (≥186 mg/dL) from 28 000 female participants aged between 25 to 40 years of a population-based cohort study. The resulting groups include 119 and 121 women, respectively, of an average 33 years of age. A gene-sequencing panel was used to assess established monogenic and polygenic origins of these phenotypes. Information on lifestyle was extracted from questionnaires. A healthy lifestyle score was allocated based on a recently developed algorithm.

Results:

Of the women with LDL-C ≤1st percentile, 19 (15.7%) carried mutations that are causing monogenic hypocholesterolemia and 60 (49.6%) were genetically predisposed to low LDL-C on the basis of an extremely low weighted genetic risk score. In comparison with control groups, a healthier lifestyle was not associated with low LDL-C in women without genetic predispositions. Among women with LDL-C ≥99th percentile, 20 women (16.8%) carried mutations that cause familial hypercholesterolemia, whereas 25 (21%) were predisposed to high LDL-C on the basis of a high-weighted genetic risk score. The women in whom no genetic origin for hypercholesterolemia could be identified were found to exhibit a significantly unfavorable lifestyle in comparison with controls.

Conclusions:

This study highlights the need for early assessment of the cardiovascular risk profile in apparently healthy young women to identify those with LDL-C ≥99th percentile for their age: first, because, in this study, 17% of the cases were molecularly diagnosed with familial hypercholesterolemia, which needs further attention; second, because our data indicate that an unfavorable lifestyle is significantly associated with severe hypercholesterolemia in genetically unaffected women, which may also need further attention.

Imputation of Baseline LDL Cholesterol Concentration in Patients with Familial Hypercholesterolemia on Statins or Ezetimibe

BACKGROUND

Familial hypercholesterolemia (FH) is the most frequent genetic disorder seen clinically and is characterized by increased LDL cholesterol (LDL-C) (>95th percentile), family history of increased LDL-C, premature atherosclerotic cardiovascular disease (ASCVD) in the patient or in first-degree relatives, presence of tendinous xanthomas or premature corneal arcus, or presence of a pathogenic mutation in the LDLR, PCSK9, or APOB genes. A diagnosis of FH has important clinical implications with respect to lifelong risk of ASCVD and requirement for intensive pharmacological therapy. The concentration of baseline LDL-C (untreated) is essential for the diagnosis of FH but is often not available because the individual is already on statin therapy.

METHODS

To validate a new algorithm to impute baseline LDL-C, we examined 1297 patients. The baseline LDL-C was compared with the imputed baseline obtained within 18 months of the initiation of therapy. We compared the percent reduction in LDL-C on treatment from baseline with the published percent reductions.

RESULTS

After eliminating individuals with missing data, nonstandard doses of statins, or medications other than statins or ezetimibe, we provide data on 951 patients. The mean ± SE baseline LDL-C was 243.0 (2.2) mg/dL [6.28 (0.06) mmol/L], and the mean ± SE imputed baseline LDL-C was 244.2 (2.6) mg/dL [6.31 (0.07) mmol/L] (P = 0.48). There was no difference in response according to the patient's sex or in percent reduction between observed and expected for individual doses or types of statin or ezetimibe.

CONCLUSIONS

We provide a validated estimation of baseline LDL-C for patients with FH that may help clinicians in making a diagnosis.

Clinical Application of Genetic Testing in Heart Failure

PURPOSE OF REVIEW

The purpose of this review is to present our current understanding of the genetic etiologies that may cause or predispose to heart failure. We highlight known phenotypes for which a genetic evaluation has clinical utility.

RECENT FINDINGS

The literature continues to demonstrate and confirm a genetic basis for conditions that cause heart failure. Evidence suggests a genetic model involving rare and common variants of strong or weak effect, in combination with environmental factors that may manifest as familial or simplex disease. Clinical genetic testing is available for several phenotypes, which can aid in the diagnosis and identification of at-risk family members. The evaluation of heart failure should include investigating etiologies with a genetic basis. Conducting a genetic evaluation in patients with heart failure requires the ability to identify possible genetic etiologies in an individual's phenotype, obtain relevant family history, and clinically interpret genetic testing results.

Genetic Architecture of Familial Hypercholesterolaemia

PURPOSE OF REVIEW

Familial hypercholesterolaemia (FH) is an inherited disorder of low-density lipoprotein cholesterol (LDL-C) which is characterised by a raised cholesterol level from birth and a high risk of premature coronary heart disease. In this paper, we review the genetic basis of FH and its impact on the clinical presentation.

RECENT FINDINGS

Mutations in any of three genes (LDLR, APOB and PCSK9) are known to cause autosomal dominant FH, but a mutation can be found in only ∼40% of patients with a clinical diagnosis of FH. In the remainder, a polygenic aetiology is most likely, due to the co-inheritance of common LDL-C-raising variants. The cardiovascular presentation and management of FH will differ between patients based on their underlying genetic factors. New genotyping methods such as next-generation sequencing will provide us with better understanding of the genetic architecture of FH.

Coronary Artery Plaque Regression by a PCSK9 Antibody and Rosuvastatin in Double-heterozygous Familial Hypercholesterolemia with an LDL Receptor Mutation and a PCSK9 V4I Mutation

The low-density lipoprotein-cholesterol (LDL-C) level of a 38-year-old man diagnosed with acute coronary syndrome was 257 mg/dL. The administration of a proprotein convertase subtilisin-kexin type 9 (PCSK9) antibody in addition to rosuvastatin plus ezetimibe was initiated, reducing his LDL-C level to 37 mg/dL. A genetic analysis revealed both an LDL receptor (LDLR) mutation and a PCSK9 V4I mutation. Nine months after revascularization, intravascular ultrasound revealed plaque regression in the coronary arteries. LDLR/PCSK9 mutation carriers are prone to coronary artery disease. Intensive LDL-C lowering by including PCSK9 antibody was associated with coronary plaque regression, suggesting the expectation of prognosis improvement.

Familial Hypercholesterolaemia Diagnosis and Management

Familial hypercholesterolaemia is the most common monogenic disorder associated with premature coronary artery disease. Mutations are most frequently found in the LDL receptor gene. Clinical criteria can be used to make the diagnosis; however, genetic testing will confirm the disorder and is very useful for cascade screening. Early identification and adequate treatment can improve prognosis, reducing negative clinical cardiovascular outcomes. Patients with familial hypercholesterolaemia are considered at high cardiovascular risk and the treatment target is LDL cholesterol <2.6 mmol/l or at least a 50 % reduction in LDL cholesterol. Patients require intensive treatment with statins and ezetimibe and/or colesevelam. Recently, proprotein convertase subtilisin/kexin type 9 inhibitors have been approved for the management of familial hypercholesterolaemia on top of statins.

Spectrum of mutations in index patients with familial hypercholesterolemia in Singapore: Single center study

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disease characterized by the presence of high plasma low density lipoproteins cholesterol (LDL-c). Patients with FH, with mutation detected, are at increased risk of premature cardiovascular disease compared to those without mutations. The aim of the study was to assess the type of mutations in patients, clinically diagnosed with FH in Singapore.

METHODS

Patients (probands) with untreated/highest on-treatment LDL-c>4.9 mmol/l were recruited (June 2015 to April 2017). Anthropometric, biochemical indices, blood and family history were collected. DNA was extracted and Next Generation Sequencing (NGS) was performed in 26 lipid-related genes, including LDLR, APOB and PCSK9, and validated using Sanger. Multiplex-ligation probe analyses for LDLR were performed to identify large mutation derangements. Based on HGVS nomenclature, LDLR mutations were classified as "Null"(nonsense, frameshift, large rearrangements) and "Defective"(point mutations which are pathogenic).

RESULTS

Ninety-six probands were recruited: mean age: (33.5 ± 13.6) years. 52.1% (n = 50) of patients had LDLR mutations, with 15 novel mutations, and 4.2% (n = 4) had APOB mutations. Total cholesterol (TC) and LDL-c were significantly higher in those with LDLR mutations compared to APOB and no mutations [(8.53 ± 1.52) vs. (6.93 ± 0.47) vs. (7.80 ± 1.32)] mmol/l, p = 0.012 and [(6.74 ± 0.35) vs. (5.29 ± 0.76) vs. (5.98 ± 1.23)] mmol/l, p=0.005, respectively. Patients with "null LDLR" mutations (n = 13) had higher TC and LDL-c than "defective LDLR" mutations (n = 35): [(9.21 ± 1.60) vs. (8.33 ± 1.41)]mmol/l, p = 0.034 and [(7.43 ± 1.47) vs. (6.53 ± 1.21)]mmol/l, p=0.017, respectively.

CONCLUSIONS

To our knowledge, this is the first report of mutation detection in patients with clinically suspected FH by NGS in Singapore. While percentage of mutations is similar to other countries, the spectrum locally differs.

Familial hypercholesterolaemia

Familial hypercholesterolaemia is a common inherited disorder characterized by abnormally elevated serum levels of low-density lipoprotein (LDL) cholesterol from birth, which in time can lead to cardiovascular disease (CVD). Most cases are caused by autosomal dominant mutations in LDLR, which encodes the LDL receptor, although mutations in other genes coding for proteins involved in cholesterol metabolism or LDLR function and processing, such as APOB and PCSK9, can also be causative, although less frequently. Several sets of diagnostic criteria for familial hypercholesterolaemia are available; common diagnostic features are an elevated LDL cholesterol level and a family history of hypercholesterolaemia or (premature) CVD. DNA-based methods to identify the underlying genetic defect are desirable but not essential for diagnosis. Cascade screening can contribute to early diagnosis of the disease in family members of an affected individual, which is crucial because familial hypercholesterolaemia can be asymptomatic for decades. Clinical severity depends on the nature of the gene that harbours the causative mutation, among other factors, and is further modulated by the type of mutation. Lifelong LDL cholesterol-lowering treatment substantially improves CVD-free survival and longevity. Statins are the first-line therapy, but additional drugs, such as ezetimibe, bile acid sequestrants, PCSK9 inhibitors and other emerging therapies, are often required.

Genetics of Dyslipidemia and Ischemic Heart Disease

PURPOSE OF REVIEW

Genetic dyslipidemias contribute to the prevalence of ischemic heart disease. The field of genetic dyslipidemias and their influence on atherosclerotic heart disease is rapidly developing and accumulating increasing evidence. The purpose of this review is to describe the current state of knowledge in regard to inherited atherogenic dyslipidemias. The disorders of familial hypercholesterolemia (FH) and elevated lipoprotein(a) will be detailed. Genetic technology has made rapid advancements, leading to new discoveries in inherited atherogenic dyslipidemias, which will be explored in this review, as well as a description of possible future developments. Increasing attention has come upon the genetic disorders of familial hypercholesterolemia and elevated lipoprotein(a).

RECENT FINDINGS

This review includes new knowledge of these disorders including description of these disorders, their method of diagnosis, their prevalence, their genetic underpinnings, and their effect on the development of cardiovascular disease. In addition, it discusses major advances in genetic technology, including the completion of the human genome sequence, next-generation sequencing, and genome-wide association studies. Also discussed are rare variant studies with specific genetic mechanisms involved in inherited dyslipidemias, such as in the proprotein convertase subtilisin/kexin type 9 (PCSK9) enzyme. The field of genetics of dyslipidemia and cardiovascular disease is rapidly growing, which will result in a bright future of novel mechanisms of action and new therapeutics.

Identification and in vitro characterization of two new PCSK9 Gain of Function variants found in patients with Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by pathogenic variants in genes encoding for LDL receptor (LDLR), Apolipoprotein B and Proprotein convertase subtilisin/kexin type 9 (PCSK9). Among PCSK9 variants, only Gain-of- Function (GOF) variants lead to FH. Greater attention should be paid to the classification of variants as pathogenic. Two hundred sixty nine patients with a clinical suspect of FH were screened for variants in LDLR and the patients without pathogenic variants were screened for variants in PCSK9 and APOB. Functional characterization of PCSK9 variants was performed by assessment of protein secretion, of LDLR activity in presence of PCSK9 variant proteins as well as of the LDLR affinity of the PCSK9 variants. Among 81 patients without pathogenic variants in LDLR, 7 PCSK9 heterozygotes were found, 4 of whom were carriers of variants whose role in FH pathogenesis is still unknown. Functional characterization revealed that two variants (p.(Ser636Arg) and p.(Arg357Cys)) were GOF variants. In Conclusions, we demonstrated a GOF effect of 2 PCSK9 variants that can be considered as FH-causative variants. The study highlights the important role played by functional characterization in integrating diagnostic procedures when the pathogenicity of new variants has not been previously demonstrated.

LDL cholesterol level in fifth-grade schoolchildren associates with stature

Short stature is associated with increased LDL-cholesterol levels and coronary artery disease in adults. We investigated the relationship of stature to LDL levels in children in the West Virginia Coronary Artery Risk Detection in Appalachian Communities (CARDIAC) Project to determine whether the genetically determined inverse relationship observed in adults would be evident in fifth graders. A cross-sectional survey of schoolchildren was assessed for cardiovascular risk factors. Data collected at school screenings over 18 years in WV schools were analyzed for 63,152 fifth-graders to determine relationship of LDL to stature with consideration of age, gender, and BMI. The first (shortest) quartile showed an LDL level of 93.6 mg/dl compared with an LDL level of 89.7 mg/dl for the fourth (tallest) quartile. Each incremental increase of 1 SD of height lowered LDL by 0.049 mg/dl (P < 0.0001). Multivariate analysis showed LDL to vary inversely as a function of the first (lowest) quartile of height after controlling for gender, median age, BMI percentile for age and gender, and year of screening. The odds ratio for LDL ≥ 130 mg/dl for shortest versus tallest quartile is 1.266 (95% CL 1.162-1.380). The odds ratio for LDL ≥ 160 mg/dl is 1.456 (95% CL 1.163-1.822). The relationship between short stature and LDL, noted in adults, is confirmed in childhood.

Polygenic determinants in extremes of high-density lipoprotein cholesterol

HDL cholesterol (HDL-C) remains a superior biochemical predictor of CVD risk, but its genetic basis is incompletely defined. In patients with extreme HDL-C concentrations, we concurrently evaluated the contributions of multiple large- and small-effect genetic variants. In a discovery cohort of 255 unrelated lipid clinic patients with extreme HDL-C levels, we used a targeted next-generation sequencing panel to evaluate rare variants in known HDL metabolism genes, simultaneously with common variants bundled into a polygenic trait score. Two additional cohorts were used for validation and included 1,746 individuals from the Montréal Heart Institute Biobank and 1,048 individuals from the University of Pennsylvania. Findings were consistent between cohorts: we found rare heterozygous large-effect variants in 18.7% and 10.9% of low- and high-HDL-C patients, respectively. We also found common variant accumulation, indicated by extreme polygenic trait scores, in an additional 12.8% and 19.3% of overall cases of low- and high-HDL-C extremes, respectively. Thus, the genetic basis of extreme HDL-C concentrations encountered clinically is frequently polygenic, with contributions from both rare large-effect and common small-effect variants. Multiple types of genetic variants should be considered as contributing factors in patients with extreme dyslipidemia.

An enquiry based on a standardised questionnaire into knowledge, awareness and preferences concerning the care of familial hypercholesterolaemia among primary care physicians in the Asia-Pacific region: the "Ten Countries Study"

OBJECTIVE

To determine physicians' knowledge, awareness and preferences regarding the care of familial hypercholesterolaemia (FH) in the Asia-Pacific region.

SETTING

A formal questionnaire was anonymously completed by physicians from different countries/regions in the Asia-Pacific. The survey sought responses relating to general familiarity, awareness of management guidelines, identification (clinical characteristics and lipid profile), prevalence and inheritance, extent of elevation in risk of cardiovascular disease (CVD) and practice on screening and treatment.

PARTICIPANTS

Practising community physicians from Australia, Japan, Malaysia, South Korea, Philippines, Hong Kong, China, Vietnam and Taiwan were recruited to complete the questionnaire, with the UK as the international benchmark.

PRIMARY OUTCOME

An assessment and comparison of the knowledge, awareness and preferences of FH among physicians in 10 different countries/regions.

RESULTS

1078 physicians completed the questionnaire from the Asia-Pacific region; only 34% considered themselves to be familiar with FH. 72% correctly described FH and 65% identified the typical lipid profile, with a higher proportion of physicians from Japan and China selecting the correct FH definition and lipid profile compared with those from Vietnam and Philippines. However, less than half of the physician were aware of national or international management guidelines; this was significantly worse than physicians from the UK (35% vs 61%, p<0.001). Knowledge of prevalence (24%), inheritability (41%) and CVD risk (9%) of FH were also suboptimal. The majority of the physicians considered laboratory interpretative commenting as being useful (81%) and statin therapy as an appropriate cholesterol-lowering therapy (89%) for FH management.

CONCLUSIONS

The study identified important gaps, which are readily addressable, in the awareness and knowledge of FH among physicians in the region. Implementation of country-specific guidelines and extensive work in FH education and awareness programmes are imperative to improve the care of FH in the region.

Low-Density Lipoprotein Cholesterol Lowering for the Primary Prevention of Cardiovascular Disease Among Men With Primary Elevations of Low-Density Lipoprotein Cholesterol Levels of 190 mg/dL or Above: Analyses From the WOSCOPS (West of Scotland Coronary Prevention Study) 5-Year Randomized Trial and 20-Year Observational Follow-Up

BACKGROUND

Patients with primary elevations of low-density lipoprotein cholesterol (LDL-C) ≥190 mg/dL are at a higher risk of atherosclerotic cardiovascular disease as a result of long-term exposure to markedly elevated LDL-C levels. Therefore, initiation of statin therapy is recommended for these individuals. However, there is a lack of randomized trial evidence supporting these recommendations in primary prevention. In the present analysis, we provide hitherto unpublished data on the cardiovascular effects of LDL-C lowering among a primary prevention population with LDL-C ≥190 mg/dL.

METHODS

We aimed to assess the benefits of LDL-C lowering on cardiovascular outcomes among individuals with primary elevations of LDL-C ≥190 mg/dL without preexisting vascular disease at baseline. We performed post hoc analyses from the WOSCOPS (West of Scotland Coronary Prevention Study) randomized, placebo-controlled trial, and observational posttrial long-term follow-up, after excluding individuals with evidence of vascular disease at baseline. WOSCOPS enrolled 6595 men aged 45 to 64 years, who were randomly assigned to pravastatin 40 mg/d or placebo. In the present analyses, 5529 participants without evidence of vascular disease were included, stratified by LDL-C levels into those with LDL-C <190 mg/dL (n=2969; mean LDL-C 178±6 mg/dL) and those with LDL-C ≥190 mg/dL (n=2560; mean LDL-C 206±12 mg/dL). The effect of pravastatin versus placebo on coronary heart disease and major adverse cardiovascular events were assessed over the 4.9-year randomized controlled trial phase and on mortality outcomes over a total of 20 years of follow-up.

RESULTS

Among 5529 individuals without vascular disease, pravastatin reduced the risk of coronary heart disease by 27% (P=0.002) and major adverse cardiovascular events by 25% (P=0.004) consistently among those with and without LDL-C ≥190 mg/dL (P-interaction >0.9). Among individuals with LDL-C ≥190 mg/dL, pravastatin reduced the risk of coronary heart disease by 27% (P=0.033) and major adverse cardiovascular events by 25% (P=0.037) during the initial trial phase and the risk of coronary heart disease death, cardiovascular death, and all-cause mortality by 28% (P=0.020), 25% (P=0.009), and 18% (P=0.004), respectively, over a total of 20 years of follow-up.

CONCLUSIONS

The present analyses provide robust novel evidence for the short- and long-term benefits of lowering LDL-C for the primary prevention of cardiovascular disease among individuals with primary elevations of LDL-C ≥190 mg/dL.

2017 Focused Update of the 2016 ACC Expert Consensus Decision Pathway on the Role of Non-Statin Therapies for LDL-Cholesterol Lowering in the Management of Atherosclerotic Cardiovascular Disease Risk: A Report of the American College of Cardiology Task Force on Expert Consensus Decision Pathways

In 2016, the American College of Cardiology published the first expert consensus decision pathway (ECDP) on the role of non-statin therapies for low-density lipoprotein (LDL)-cholesterol lowering in the management of atherosclerotic cardiovascular disease (ASCVD) risk. Since the publication of that document, additional evidence and perspectives have emerged from randomized clinical trials and other sources, particularly considering the longer-term efficacy and safety of proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors in secondary prevention of ASCVD. Most notably, the FOURIER (Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk) trial and SPIRE-1 and -2 (Studies of PCSK9 Inhibition and the Reduction of Vascular Events), assessing evolocumab and bococizumab, respectively, have published final results of cardiovascular outcomes trials in patients with clinical ASCVD and in a smaller number of high-risk primary prevention patients. In addition, further evidence on the types of patients most likely to benefit from the use of ezetimibe in addition to statin therapy after acute coronary syndrome has been published. Based on results from these important analyses, the ECDP writing committee judged that it would be desirable to provide a focused update to help guide clinicians more clearly on decision making regarding the use of ezetimibe and PCSK9 inhibitors in patients with clinical ASCVD with or without comorbidities. In the following summary table, changes from the 2016 ECDP to the 2017 ECDP Focused Update are highlighted, and a brief rationale is provided. The content of the full document has been changed accordingly, with more extensive and detailed guidance regarding decision making provided both in the text and in the updated algorithms. Revised recommendations are provided for patients with clinical ASCVD with or without comorbidities on statin therapy for secondary prevention. The ECDP writing committee judged that these new data did not warrant changes to the decision pathways and algorithms regarding the use of ezetimibe or PCSK9 inhibitors in primary prevention patients with LDL-C <190 mg/dL with or without diabetes mellitus or patients without ASCVD and LDL-C ≥190 mg/dL not due to secondary causes. Based on feedback and further deliberation, the ECDP writing committee down-graded recommendations regarding bile acid sequestrant use, recommending bile acid sequestrants only as optional secondary agents for consideration in patients intolerant to ezetimibe. For clarification, the writing committee has also included new information on diagnostic categories of heterozygous and homozygous familial hypercholesterolemia, based on clinical criteria with and without genetic testing. Other changes to the original document were kept to a minimum to provide consistent guidance to clinicians, unless there was a compelling reason or new evidence, in which case justification is provided.

Improving Universal Pediatric Lipid Screening

OBJECTIVE

To evaluate whether the release of national guidelines, electronic health record (EHR) modifications, and educational initiatives correlated with changes in pediatricians' universal lipid screening practices.

STUDY DESIGN

Retrospective review of EHRs in an academic general pediatric practice was performed to measure the prevalence of order placement. A child was "screened" if an order was placed during a well-visit between 9 and 21 years of age. The prevalence of order placement for lipid screens on 22 374 patients from January 2010 to December 2015 was analyzed for date of order and patient age, then compared with timing of guidelines, local educational initiatives, and EHR modifications. Primary study outcome was lipid screening order placement over time.

RESULTS

Order placement increased from 8.9% (95% CI 8.3%-9.5%) before any intervention to 50.0% (95% CI 48.8%-51.2%) over the last 12 months of the study period (P < .001). All age groups showed significant increases in order placement. Changes in screening were seen following guideline publications, educational initiatives, and EHR modifications (for all, P < .0001). Order completion was 69.6% (95% CI 68.9%-70.3%). The composite prevalence of screening (order placement multiplied by order completion) was 46.8% over the 6-year study period.

CONCLUSIONS

Improved adherence to recommendations for universal lipid screening is possible through educational initiatives and EHR modifications. Inclusion of 12- to 16-year-old adolescents/teenagers as a targeted group for universal screening in addition to recommended age groups improved screening prevalence. Similar efforts could be applicable for implementation of other guidelines.

Estimating the prevalence of heterozygous familial hypercholesterolaemia: a systematic review and meta-analysis

OBJECTIVES

Heterozygous familial hypercholesterolaemia (FH) confers a significant risk for premature cardiovascular disease (CVD). However, the estimated prevalence of FH varies substantially among studies. We aimed to provide a summary estimate of FH prevalence in the general population and assess variations in frequency across different sociodemographic characteristics.

SETTING, PARTICIPANTS AND OUTCOME MEASURES

We searched MEDLINE, EMBASE, Global Health, the Cochrane Library, PsycINFO and PubMed for peer-reviewed literature using validated strategies. Results were limited to studies published in English between January 1990 and January 2017. Studies were eligible if they determined FH prevalence using clinical criteria or DNA-based analyses. We determined a pooled point prevalence of FH in adults and children and assessed the variation of the pooled frequency by age, sex, geographical location, diagnostic method, study quality and year of publication. Estimates were pooled using random-effects meta-analysis. Differences by study-level characteristics were investigated through subgroups, meta-regression and sensitivity analyses.

RESULTS

The pooled prevalence of FH from 19 studies including 2 458 456 unique individuals was 0.40% (95% CI 0.29% to 0.52%) which corresponds to a frequency of 1 in 250 individuals. FH prevalence was found to vary by age and geographical location but not by any other covariates. Results were consistent in sensitivity analyses.

CONCLUSIONS

Our systematic review suggests that FH is a common disorder, affecting 1 in 250 individuals. These findings underscore the need for early detection and management to decrease CVD risk.

Beyond cascade screening: detection of familial hypercholesterolaemia at childhood immunization and other strategies

PURPOSE OF REVIEW

Familial hypercholesterolaemia is a common genetic disorder that accelerates premature coronary heart disease. Although effective treatments are available, the majority of individuals remain undiagnosed. We review new evidence for improving the detection of familial hypercholesterolaemia.

RECENT FINDINGS

Recent studies have demonstrated that universal screening of children for familial hypercholesterolaemia may be highly effective at the time of immunization if combined with reverse cascade testing of adult family members, who have a more immediate risk of a coronary event. Alerts on laboratory reports and the application of bioinformatics to electronic health records may also be useful for identifying familial hypercholesterolaemia in community settings. Effective detection, diagnosis, and codification of familial hypercholesterolaemia are essential for the development of registries.

SUMMARY

Although the cost-effectiveness of screening programs for familial hypercholesterolaemia in childhood remains to be established, combining universal and reverse cascade screening, complemented by opportunistic identification of individuals in high-risk settings, use of laboratory alerts, and screening of electronic health records are likely to have a high yield in the detection of familial hypercholesterolaemia in the community.

[Not Available]

Zusammenfassung. Die Dyslipidämie stellt einen der wichtigsten kardiovaskulären Risikofaktoren dar. Massnahmen dagegen sind deshalb von zentraler Bedeutung. Die Behandlung erhöhter Lipidwerte mit Statinen hat sich dabei als besonders erfolgreich erwiesen. Die Indikation zur lipidsenkenden Therapie richtet sich nach dem kardiovaskulären Risiko. Patienten, die bereits an atherosklerotischen Krankheiten oder Niereninsuffizienz leiden, bzw. an Diabetes Typ 1 mit Organschäden oder Typ 2 mit weiteren Risikofaktoren, oder solche mit familiärer Hypercholesterinämie, gelten als Hochrisikopatienten und sollten entsprechend behandelt werden. Bei allen übrigen empfiehlt sich die Berechnung des 10-Jahres-Risikos. In der Schweiz werden gewöhnlich der modifizierte PROCAM-Score/Algorithmus der AGLA und der Score der EAS/ESC verwendet. Die Intensität der Behandlung hängt vom kardiovaskulären Risiko ab.

Rapidly progressive atherosclerosis after domino liver transplantation from a teenage donor with homozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by impaired clearance of low-density lipoprotein cholesterol. Given limitations in pharmacologic therapy and the significant morbidity and mortality associated with this disease, liver transplantation may be offered to select homozygous FH patients in childhood in an effort to slow progression of atherosclerotic cardiovascular disease. In rare cases, domino liver transplantation can be performed, transplanting the livers of patients with various metabolic disorders into elderly recipients whose projected survival precludes prolonged waiting on the transplant list. Herein, we report a case of domino liver transplantation using the liver of a 14-year-old boy with homozygous FH into a 65-year-old man with primary sclerosing cholangitis and cirrhosis who developed rapidly progressive atherosclerotic cardiovascular disease involving the arteries of his proximal bilateral lower extremities, carotid arteries and superior mesenteric artery.

The prevalence of familial hypercholesterolemia in the West Siberian region of the Russian Federation: A substudy of the ESSE-RF

Background

The prevalence of familial hypercholesterolemia (FH) in Russia has not previously been evaluated. The aim of our study was to investigate the prevalence of FH in the population of the West Siberian region of Russia, and then estimate the frequency of coronary artery disease (CAD) and treatment with cholesterol-lowering medication in FH patients.

Methods

The sample of our study consisted of participants from the population-based cohort of The Epidemiology of Cardiovascular Risk Factors and Diseases in Regions of the Russian Federation Study (ESSE-RF), conducted in the Tyumen and Kemerovo regions (1,630 and 1,622 people, respectively, aged 25–64). All participants who had LDL-cholesterol higher than 4.9 mmol/l and who had LDL-cholesterol less than or equal to 4.9 mmol/l but had statin therapy were examined and interviewed by experts in FH.

Results

The prevalence of patients with definite FH was 0.24% (one in 407) (95% confidence interval [CI]: 0.06%–0.42%), with probable FH was 0.68% (one in 148) (95% CI: 0.38%–0.98%), and with definite or probable FH combined was 0.92% (one in 108) (95% CI: 0.58%–1.26%). 40% (95% CI: 20.8%–59.2%) of patients with definite or probable FH had CAD. However, only 23% (95% CI: 6.3%–39.7%) of patients with definite or probable FH were on statins. The odds ratios for CAD and myocardial infarction (MI), adjusted for age, gender, region, smoking, hypertension, and diabetes mellitus, were 3.71 (95% CI: 1.58–8.72) (p = 0.003) and 4.06 (95% CI: 0.89–18.55) (р = 0.070) respectively for individuals with definite or probable FH relative to those who were unlikely to have FH.

Conclusions

The prevalence of FH in Russia may be significantly higher than previously estimated. There is underdiagnosis and undertreatment of FH in Russia.

Editor-in-Chief's Top Picks From 2016: Part Two

Each week, I record audio summaries for every article in JACC, as well as an issue summary. While this process has been incredibly time-consuming, I have become quite familiar with every paper that we publish. Thus, I personally select papers (both original investigations and review articles) from 15 distinct specialties each year for your review. In addition to my personal choices, I have included manuscripts that have been the most accessed or downloaded on our websites, as well as those selected by the JACC Editorial Board members. In order to present the full breadth of this important research in a consumable fashion, we will present these manuscripts in this issue of JACC. Part One included the sections: Basic & Translational Research, Cardiac Failure, Cardiomyopathies/Myocardial & Pericardial Diseases, Congenital Heart Disease, Coronary Disease & Interventions, and CVD Prevention & Health Promotion. Part Two includes the sections: CV Medicine & Society, Hypertension, Imaging, Metabolic & Lipid Disorders, Rhythm Disorders, Valvular Heart Disease, and Vascular Medicine (1-84).

Clinical Features and Gaps in the Management of Probable Familial Hypercholesterolemia and Cardiovascular Disease

BACKGROUND

Familial hypercholesterolemia (FH) is associated with premature atherosclerotic cardiovascular disease (ASCVD). The introduction of potent therapeutic agents underlies the importance of improving clinical diagnosis and treatment gaps in FH.Methods and Results:A regional database of 1,690 adult patients with high-probability FH based on age-dependent peak-low-density lipoprotein cholesterol (LDL-C) cut-offs and exclusion of secondary causes of severe hypercholesterolemia, was examined to explore the clinical manifestations and current needs in the management of ASCVD, which was present in 248 patients (15%), of whom 83% had coronary artery disease (CAD); 19%, stroke; and 13%, peripheral artery disease. ASCVD was associated with male gender, higher peak LDL-C, lower high-density lipoprotein cholesterol (HDL-C), and traditional risk factor burden. Despite high-intensity statin (prescribed in 83% and combined with ezetimibe in 42%), attainment of LDL-C treatment goals was low, and associated with treatment intensity and drug adherence. Multivessel CAD (adjusted hazard ratios (HR), 3.05; 95% CI: 1.65-5.64), myocardial infarction, and the presence of ≥1 traditional risk factor (HR, 2.59; 95% CI: 1.42-4.71), were associated with repeat coronary revascularizations, in contrast with peak LDL-C >300 mg/dL (HR, 1.13; 95% CI: 0.66-1.91).

CONCLUSIONS

Main manifestations of ASCVD in FH patients were premature, multivessel CAD with need for recurrent revascularization, associated with classical cardiovascular risk factors but not with peak LDL-C. In spite of intensive therapy with lipid-lowering agents, treatment gaps were significant, with low attainment of LDL-C treatment goals.

Knowns and unknowns in the care of pediatric familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a common genetic disorder that causes elevated LDL cholesterol levels from birth. Untreated FH accelerates atherosclerosis and predisposes individuals to premature coronary artery disease (CAD) in adulthood. Mendelian randomization studies have demonstrated that LDL cholesterol has both a causal and cumulative effect on the risk of CAD. This supports clinical recommendations that children with FH commence pharmacological treatment from the age of 8 to 10 years, to reduce the burden of hypercholesterolemia. Worldwide, the majority of children with FH remain undiagnosed. Recent evidence suggests that the frequency of FH is at least 1 in 250 and this constitutes a public health issue. We review and identify the knowns and unknowns concerning the detection and management of pediatric FH that impact on the developing model of care for this condition.

Statins for children with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia is one of the most common inherited metabolic diseases and is an autosomal dominant disorder meaning heterozygotes, or carriers, are affected. Those who are homozygous have severe disease. The average worldwide prevalence of heterozygous familial hypercholesterolemia is at least 1 in 500, although recent genetic epidemiological data from Denmark and next generation sequencing data suggest the frequency may be closer to 1 in 250. Diagnosis of familial hypercholesterolemia in children is based on elevated total cholesterol and low-density lipoprotein cholesterol levels or DNA-based analysis, or both. Coronary atherosclerosis has been detected in men with heterozygous familial hypercholesterolemia as young as 17 years old and in women with heterozygous familial hypercholesterolemia at 25 years old. Since the clinical complications of atherosclerosis occur prematurely, especially in men, lifelong treatment, started in childhood, is needed to reduce the risk of cardiovascular disease. In children with the disease, diet was the cornerstone of treatment but the addition of lipid-lowering medications has resulted in a significant improvement in treatment. Anion exchange resins, such as cholestyramine and colestipol, were found to be effective, but they are poorly tolerated. Since the 1990s studies carried out on children aged 6 to 17 years with heterozygous familial hypercholesterolemia have demonstrated significant reductions in their serum total and low-density lipoprotein cholesterol levels. While statins seem to be safe and well-tolerated in children, their long-term safety in this age group is not firmly established. This is an update of a previously published version of this Cochane Review.

OBJECTIVES

To assess the effectiveness and safety of statins in children with heterozygous familial hypercholesterolemia.

SEARCH METHODS

Relevant studies were identified from the Group's Inborn Errors and Metabolism Trials Register and Medline.Date of most recent search: 20 February 2017.

SELECTION CRITERIA

Randomized and controlled clinical studies including participants up to 18 years old, comparing a statin to placebo or to diet alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data.

MAIN RESULTS

We found 26 potentially eligible studies, of which we included nine randomized placebo-controlled studies (1177 participants). In general, the intervention and follow-up time was short (median 24 weeks; range from six weeks to two years). Statins reduced the mean low-density lipoprotein cholesterol concentration at all time points (moderate quality evidence). Serum aspartate and alanine aminotransferase, as well as creatinine kinase concentrations, did not differ between treated and placebo groups at any time point (low quality evidence). The risks of myopathy (low quality evidence) and clinical adverse events (moderate quality evidence) were very low and also similar in both groups. In one study simvastatin was shown to improve flow-mediated dilatation of the brachial artery (low quality evidence), and in another study treatment with pravastatin for two years induced a significant regression in carotid intima media thickness (low quality evidence).

AUTHORS' CONCLUSIONS

Statin treatment is an effective lipid-lowering therapy in children with familial hypercholesterolemia. No significant safety issues were identified. Statin treatment seems to be safe in the short term, but long-term safety remains unknown. Children treated with statins should be carefully monitored and followed up by their pediatricians and their care transferred to an adult lipidologist once they reach 18 years of age. Large long-term randomized controlled trials are needed to establish the long-term safety issues of statins.

Genetics: Implications for Prevention and Management of Coronary Artery Disease

An exciting new era has dawned for the prevention and management of coronary artery disease (CAD) utilizing genetic risk variants. The recent identification of over 60 susceptibility loci for CAD confirms not only the importance of established risk factors, but also the existence of many novel causal pathways that are expected to improve our understanding of the genetic basis of CAD and facilitate the development of new therapeutic agents over time. Concurrently, Mendelian randomization studies have provided intriguing insights on the causal relationship between CAD-related traits, and highlight the potential benefits of long-term modifications of risk factors. Last, genetic risk scores of CAD may serve not only as prognostic, but also as predictive markers, and carry the potential to considerably improve the delivery of established prevention strategies. This review will summarize the evolution and discovery of genetic risk variants for CAD and their current and future clinical applications.

Protein-Truncating Variants at the Cholesteryl Ester Transfer Protein Gene and Risk for Coronary Heart Disease

RATIONALE

Therapies that inhibit CETP (cholesteryl ester transfer protein) have failed to demonstrate a reduction in risk for coronary heart disease (CHD). Human DNA sequence variants that truncate the CETP gene may provide insight into the efficacy of CETP inhibition.

OBJECTIVE

To test whether protein-truncating variants (PTVs) at the CETP gene were associated with plasma lipid levels and CHD.

METHODS AND RESULTS

We sequenced the exons of the CETP gene in 58 469 participants from 12 case-control studies (18 817 CHD cases, 39 652 CHD-free controls). We defined PTV as those that lead to a premature stop, disrupt canonical splice sites, or lead to insertions/deletions that shift frame. We also genotyped 1 Japanese-specific PTV in 27561 participants from 3 case-control studies (14 286 CHD cases, 13 275 CHD-free controls). We tested association of CETP PTV carrier status with both plasma lipids and CHD. Among 58 469 participants with CETP gene-sequencing data available, average age was 51.5 years and 43% were women; 1 in 975 participants carried a PTV at the CETP gene. Compared with noncarriers, carriers of PTV at CETP had higher high-density lipoprotein cholesterol (effect size, 22.6 mg/dL; 95% confidence interval, 18-27; P<1.0×10-4), lower low-density lipoprotein cholesterol (-12.2 mg/dL; 95% confidence interval, -23 to -0.98; P=0.033), and lower triglycerides (-6.3%; 95% confidence interval, -12 to -0.22; P=0.043). CETP PTV carrier status was associated with reduced risk for CHD (summary odds ratio, 0.70; 95% confidence interval, 0.54-0.90; P=5.1×10-3).

CONCLUSIONS

Compared with noncarriers, carriers of PTV at CETP displayed higher high-density lipoprotein cholesterol, lower low-density lipoprotein cholesterol, lower triglycerides, and lower risk for CHD.

Prevalence of Elevated Cardiovascular Risks in Young Adults: A Cross-sectional Analysis of National Health and Nutrition Examination Surveys

BACKGROUND

The 2013 cholesterol management guidelines from the American College of Cardiology and American Heart Association (ACC/AHA) recommend lipid screening in all adults older than 20 years to identify those at increased risk for atherosclerotic cardiovascular disease (ASCVD). Statins may be considered for patients with elevated 10-year risk (>5%) or a low-density lipoprotein cholesterol (LDL-C) level of 4.92 mmol/L (190 mg/dL) or greater.

OBJECTIVE

To describe the prevalence of elevated ASCVD risk among nondiabetic adults younger than 50 years.

DESIGN

Cross-sectional.

SETTING

NHANES (National Health and Nutrition Examination Survey), 1999 to 2000 through 2011 to 2012.

PARTICIPANTS

Adults aged 30 to 49 years without known ASCVD or diabetes.

MEASUREMENTS

10-year ASCVD risk was estimated by using the 2013 ACC/AHA ASCVD risk calculator. Participants were subdivided by age, sex, and history of smoking and hypertension. The percentages of adults in each subgroup with a 10-year ASCVD risk greater than 5% and of those with an LDL-C level of 4.92 mmol/L (190 mg/dL) or greater were estimated. Low-prevalence subgroups were defined as those in which a greater than 1% prevalence of elevated cardiovascular risk could be ruled out (that is, the upper 95% confidence bound for prevalence was ≤1%).

RESULTS

Overall, 9608 NHANES participants representing 67.9 million adults were included, with approximately half (47.12%, representing 32 million adults) in low-prevalence subgroups. In the absence of smoking or hypertension, 0.09% (95% CI, 0.02% to 0.35%) of adult men younger than 40 years and 0.04% (CI, 0.0% to 0.26%) of adult women younger than 50 years had an elevated risk. Among other subgroups, 0% to 75.9% of participants had an increased risk. Overall, 2.9% (CI, 2.3% to 3.5%) had an LDL-C level of 4.92 mmol/L (190 mg/dL) or greater.

LIMITATION

No information was available regarding cardiovascular outcomes.

CONCLUSION

In the absence of risk factors, the prevalence of increased ASCVD risk is low among women younger than 50 and men younger than 40 years.

PRIMARY FUNDING SOURCE

None.

A decade of progress on the genetic basis of coronary artery disease. Practical insights for the internist

Clinicians are well aware of the importance of a positive family history for coronary artery disease (CAD). Nonetheless, elucidation of the genetic basis of CAD has long proven difficult. The scenario changed in the last decade through the application of modern genomic technologies, like genome-wide association studies (GWAS) and next generation sequencing (NGS). GWAS have discovered over 60 common variants highly associated with CAD. For predictive purposes, such variants have been used to build up Genetic Risk Scores (GRSs), but their incorporation into classical prediction models does not appear substantially outperform the simple addition of family history. To date, the only strong case for the utility of incorporating genetic testing into clinical practice is represented by the diagnosis of Familial Hypercholesterolemia (FH). On the other hand, utilization of genomic techniques has driven formidable advances into the knowledge of CAD pathophysiology, particularly by addressing controversies on the causality of some lipid fractions that had long remained unsolved because of limitations of observational epidemiology. For example, NGS-derived rare variants with strong functional effects on key-genes like ANGPTL4, APOA5, APOC3, LPL, and SCARB1, have proven useful as proxies to demonstrate the causality of triglyceride-rich lipoproteins (TRLs) at variance with HDL-cholesterol concentration, thus contributing to tear down a dogma from classical epidemiology. Moreover, such variants have paved the way for the development of new biologic drugs (i.e. monoclonal antibodies or antisense oligonucleotides) targeting key proteins like PCSK9, Lipoprotein_(a), and apolipoprotein C3. Such drugs are currently under active investigation, with first results being extremely promising.

Genetics of coronary artery disease: discovery, biology and clinical translation

Coronary artery disease is the leading global cause of mortality. Long recognized to be heritable, recent advances have started to unravel the genetic architecture of the disease. Common variant association studies have linked approximately 60 genetic loci to coronary risk. Large-scale gene sequencing efforts and functional studies have facilitated a better understanding of causal risk factors, elucidated underlying biology and informed the development of new therapeutics. Moving forwards, genetic testing could enable precision medicine approaches by identifying subgroups of patients at increased risk of coronary artery disease or those with a specific driving pathophysiology in whom a therapeutic or preventive approach would be most useful.

[Familial hypercholesterolemia: A largely underestimated cardiovascular risk]

BACKGROUND

Familial hypercholesterolemia is a monogenic autosomal dominant dyslipidemia characterized by a permanent and isolated increase of cholesterol carried by low-density lipoproteins. The prevalence of its heterozygous form is estimated between 1/500 and 1/250, and in the absence of specific treatment, this form is responsible for an increase by a factor of 13 of the risk of premature coronary artery disease compared to patients non-affected by the disease.

OBJECTIVES

To perform an inventory of the knowledge of heterozygous familial hypercholesterolemia in France for physicians involved in the management of the disease.

METHODS

A survey was conducted (by phone and internet) among a representative sample of 495 physicians (cardiologists, endocrinologists/diabetologists, gynecologists, general practitioners) who, in parallel, completed 579 patient records.

RESULTS

Thirty-two percent (95% CI [27.8; 36.2]) of physicians reported the difference between polygenic hypercholesterolemia and familial hypercholesterolemia. The presence of tendinous xanthomas, a key element of diagnosis, was spontaneously mentioned by 44% (95% CI [34; 54.2]) of cardiologists. Six percent (95% CI [2.2; 12.6]) of them gave a correct estimate of the prevalence of familial hypercholesterolemia. The likelihood of transmission of heterozygous familial hypercholesterolemia, when one parent is affected, was known for 59% (95% CI [48.7; 68.7]) of surveyed cardiologists. A cascade screening was performed systematically by 4% (95% CI [1.1; 9.9]) of them. Eighteen percent (95% CI [11; 26.9]) of cardiologists gave an accurate estimation of cardiovascular risk of heterozygous familial hypercholesterolemia. Fifty-seven percent (95% CI [46.7; 66.8]) of cardiologists admitted being misinformed about the heterozygous familial hypercholesterolemia and 83% (95% CI [74.1; 89.7]) expressed a need for information about this disease.

CONCLUSION

The lack of knowledge of heterozygous familial hypercholesterolemia and its associated cardiovascular risk is probably the cause of a diagnostic default leading to inappropriate management of this disease.

Update on the use of PCSK9 inhibitors in adults: Recommendations from an Expert Panel of the National Lipid Association

An Expert Panel convened by the National Lipid Association was charged with updating the recommendations on the use of proprotein convertase subtilisin/kexin type 9 (PCSK9) antibody therapy that were provided by the 2015 National Lipid Association Recommendations for the Patient-Centered Management of Dyslipidemia: Part 2. Recent studies have demonstrated the efficacy of these agents in reducing low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol and have confirmed their excellent safety profile. A cardiovascular outcomes study has shown that these agents reduce incident atherosclerotic cardiovascular disease (ASCVD) events in patents with stable ASCVD and concomitant risk factors. The current update provides the Expert Panel's evidence-based recommendations on the clinical utility of PCSK9 inhibitors in patients with stable ASCVD, progressive ASCVD, LDL-C ≥ 190 mg/dL (including polygenic hypercholesterolemia, heterozygous familial hypercholesterolemia and the homozygous familial hypercholesterolemia phenotype) and very-high-risk patients with statin intolerance.

Greater preclinical atherosclerosis in treated monogenic familial hypercholesterolemia vs. polygenic hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a common inherited disorder of low density lipoprotein-cholesterol (LDL-C) metabolism. It is associated with higher risk of premature coronary heart disease. Around 60% of patients with a clinical diagnosis of FH do not have a detectable mutation in the genes causing FH and are most likely to have a polygenic cause for their raised LDL-C. We assessed the degree of preclinical atherosclerosis in treated patients with monogenic FH versus polygenic hypercholesterolemia.

METHODS

FH mutation testing and genotypes of six LDL-C-associated single nucleotide polymorphisms (SNPs) were determined using routine methods. Those with a detected mutation (monogenic) and mutation-negative patients with LDL-C SNP score in the top two quartiles (polygenic) were recruited. Carotid intima media thickness (IMT) was measured by B-mode ultrasound and the coronary artery calcium (CAC) score was performed in three lipid clinics in the UK and the Netherlands.

RESULTS

86 patients (56 monogenic FH, 30 polygenic) with carotid IMT measurement, and 166 patients (124 monogenic, 42 polygenic) with CAC score measurement were examined. After adjustment for age and gender, the mean of all the carotid IMT measurements and CAC scores were significantly greater in the monogenic than the polygenic patients [carotid IMT mean (95% CI): 0.74 mm (0.7-0.79) vs. 0.66 mm (0.61-0.72), p = 0.038 and CAC score mean (95%): 24.5 (14.4-41.8) vs. 2.65 (0.94-7.44), p = 0.0004].

CONCLUSIONS

In patients with a diagnosis of FH, those with a monogenic cause have a higher severity of carotid and coronary preclinical atherosclerosis than those with a polygenic aetiology.