Child-Parent Familial Hypercholesterolemia Screening in Primary Care

Detecting familial hypercholesterolemia earlier in life by actively searching for affected children:The DECOPIN project

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is underdiagnosed in children. We assessed a combination of two screening methods. The first method was to detect hypercholesteraemic children and then study the parents (Ch-P pathway), and the second one was to study the offspring of FH-affected parents (P-Ch pathway).

METHODS

In the Ch-P path, primary care paediatricians were asked to include lipid profiling or, at least, total cholesterol (TC) and then lipid profiling if TC was higher than 5.2 mmol/L in any clinically indicated blood test. Children with LDL-C ≥ 3.5 mmol/L, plus either a family history of early cardiovascular disease or one parent with severe hypercholesterolemia, were referred to the lipid unit where the parents, rather than their children, were studied. In parents with definite, clinical FH, a genetic study was performed. Focused genetic testing was performed on all offspring of genetically positive parents. The P-Ch path consisted of the active study of children from definite FH adults.

RESULTS

Fifty-nine paediatricians covering a total population of 63,616 children agreed to participate in the project. Of the 216 children (122 Ch-P and 94 P-Ch) who were ultimately referred to the lipid unit, 87 children with FH (84% genetically positive) were identified. Additionally, 41 parents (from 40 families) were newly diagnosed with FH (63% genetically positive). Forty-nine different mutations were detected: 46 in the LDLR, 2 in the PCSK9 and 1 in APOB gene.

CONCLUSIONS

The implementation of active strategies to detect FH in children, in close collaboration with primary care paediatricians, provides a high-performance method for early FH detection.

Risk Communication in Families of Children with Familial Hypercholesterolemia: Identifying Motivators and Barriers to Cascade Screening to Improve Diagnosis at a Single Medical Center

Familial hypercholesterolemia (FH) is severely underdiagnosed in the USA; yet, factors influencing family notification about risk for FH in the US pediatric setting have not been well elucidated. Most previous research on these factors has occurred in adult patient populations in European countries with organized cascade screening programs; therefore, we sought to characterize parent experiences with cascade screening in the US pediatric setting. A quantitative survey measuring family notification of FH risk information was administered to 38 parents of children with FH identified within a pediatric cardiology clinic. Participants were also asked if family notification was impacted by intrapersonal, interpersonal, institutional, community, and public policy factors identified previously in other populations. Notification of at least one of the proband's living grandparents or aunts/uncles was reported by 76% (n = 25/33) and 71% (n = 24/34) of participants, respectively. The most common reason for notification was to protect relatives from heart disease. Two of the most common reasons participants did not notify relatives were a lack of information about FH and concern that the relative would have difficulty understanding the information. Yet, only a minority of participants (39%) accessed institutional resources such as educational materials to share with relatives or assistance drafting a family letter that could address these barriers. Based on the identified barriers and motivators for family communication, we suggest facilitators to improve implementation of cascade screening.

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

Purpose of Review

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

Recent Findings

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

Summary

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

Parent-child genetic testing for familial hypercholesterolaemia in an Australian context

AIM

The aim of this study was to evaluate the clinical outcome of parent-child testing for familial hypercholesterolaemia (FH) employing genetic testing and the likely additional cost of treating each child.

METHODS

Parent-child testing for gene variants causative of FH was carried out according to Australian guidelines. The number of new cases detected, the low-density lipoprotein (LDL)-cholesterol that best predicted a mutation and the proportional reduction in LDL-cholesterol following statin treatment was evaluated. Treatment costs were calculated as the cost per mmol/L reduction in LDL-cholesterol.

RESULTS

A total of 126 adult patients, known to have a pathogenic mutation causative of FH, and their children were studied. From 244 children identified, 148 (60.7%) were genetically screened; 84 children were identified as mutative positive (M+) and 64 as mutative negative. Six of the M+ children were already on statin treatment; 40 were subsequently treated with low-dose statins, with LDL-cholesterol falling significantly by 38% (P < 0.001). The estimated cost per mmol/L reduction of LDL-cholesterol of a child receiving statins from ages 10 to 18 years is AU$1361, which can potentially be cost-effective. An LDL-cholesterol threshold of 3.5 mmol/L had a sensitivity of 92.8% and specificity of 96.6% for the detection of a mutation.

CONCLUSION

Genetic testing of children of affected parents with FH is an effective means of detecting new cases of FH. Cascade testing can enable early statin therapy with significant reductions in LDL-cholesterol concentration.

Universal screening at age 1-2 years as an adjunct to cascade testing for familial hypercholesterolaemia in the UK: A cost-utility analysis

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) is widely underdiagnosed. Cascade testing (CT) of relatives has been shown to be feasible, acceptable and cost-effective in the UK, but requires a supply of index cases. Feasibility of universal screening (US) at age 1-2 years was recently demonstrated. We examined whether this would be a cost-effective adjunct to CT in the UK, given the current and plausible future undiagnosed FH prevalence.

METHODS

Seven cholesterol and/or mutation-based US ± reverse cascade testing (RCT) alternatives were compared with no US in an incremental analysis with a healthcare perspective. A decision model was used to estimate costs and outcomes for cohorts exposed to the US component of each strategy. RCT case ascertainment was modelled using recent UK CT data, and probabilistic Markov models estimated lifetime costs and health outcomes for the cohorts screened under each alternative. 1000 Monte Carlo simulations were run for each model, and average outcomes reported. Further uncertainty was explored deterministically. Threshold analysis investigated the association between undiagnosed FH prevalence and cost-effectiveness.

RESULTS

A strategy involving cholesterol screening followed by diagnostic genetic testing and RCT was the most cost-effective modelled (incremental cost-effectiveness ratio (ICER) versus no US £12,480/quality adjusted life year (QALY); probability of cost-effectiveness 96·8% at £20,000/QALY threshold). Cost-effectiveness was robust to both deterministic sensitivity analyses and threshold analyses that modelled ongoing case ascertainment at theoretical maximum levels.

CONCLUSIONS

These findings support implementation of universal cholesterol screening followed by diagnostic genetic testing and RCT for FH, under a UK conventional willingness-to-pay threshold.

Cost effectiveness of cascade testing for familial hypercholesterolaemia, based on data from familial hypercholesterolaemia services in the UK

Aims

Familial hypercholesterolaemia (FH) is a vastly under-diagnosed genetic disorder, associated with early development of coronary heart disease and premature mortality which can be substantially reduced by effective treatment. Patents have recently expired on high-intensity statins, reducing FH treatment costs. We build a model using UK data to estimate the cost effectiveness of DNA testing of relatives of those with monogenic FH.

Methods and Results

A Markov model was used to estimate the cost effectiveness of cascade testing, using data from UK cascade services. The estimated incremental cost effectiveness ratio (ICER) was £5806 and the net marginal lifetime cost per relative tested was £2781. More than 80% of lifetime costs were diagnosis-related and incurred in the 1st year. In UK services, 23% of 6396 index cases were mutation-positive. For each mutation-positive index case, 1.33 relatives were tested, resulting overall in a rate of 0.31 tested relatives per tested index case. If the number of relatives tested per tested index case rose to 3.2 (projected by National Institute for Health and Care Excellence in 2008) the ICER would reduce to £2280 and lifetime costs to £1092.

Conclusion

Cascade testing of relatives of those with suspected FH is highly cost effective. The current Europe-wide high levels of undiagnosed FH, and associated morbidity and mortality, mean adoption of cascade services should yield substantial quality of life and survival gains.

Blood lipid-related low-frequency variants in LDLR and PCSK9 are associated with onset age and risk of myocardial infarction in Japanese

Recent studies have revealed the importance of rare variants in myocardial infarction (MI) susceptibility in European populations. Because genetic architectures vary in different populations, we investigated how they contribute to MI susceptibility in Japanese subjects. We performed targeted sequencing of 36 coronary artery disease risk genes, identified by genome-wide association studies, in 9,956 cases and 8,373 controls. Gene-based association tests identified significant enrichment of rare variants in LDLR and PCSK9 in MI cases. We identified 52 (novel 22) LDLR variants predicted to be damaging. Carriers of these variants showed a higher risk of MI (carriers/non-carriers 89/9867 in cases, 17/8356 controls, OR = 4.4, P = 7.2 × 10⁻¹⁰), higher LDL-cholesterol levels and younger age of onset for MI. With respect to PCSK9, E32K carriers showed higher LDL-cholesterol levels and younger age of onset for MI, whereas R93C carriers had lower LDL-cholesterol levels. A significant correlation between LDL-cholesterol levels and onset age of MI was observed in these variant carriers. In good agreement with previous studies in patients with familial hypercholesterolaemia, our study in the Japanese general population showed that rare variants in LDLR and PCSK9 were associated with the onset age of MI by altering LDL-cholesterol levels.

Genetic diagnosis of familial hypercholesterolemia is associated with a premature and high coronary heart disease risk

BACKGROUND

Familial hypercholesterolemia (FH) is a common autosomal dominant disease associated with premature coronary heart disease (CHD). Studies tend to show that patients with FH associated with an identified mutation (mutation+ FH) are at higher risk than patients without an identified mutation (mutation- FH). We compared the clinical and biological profile and the risk of CHD in patients with mutation+ FH and mutation- FH.

HYPOTHESIS

In addition to LDL-C, a pathogenic mutation predicts premature CHD in FH.

METHODS

We successively included all patients with suspected FH (LDL-C > 190 mg/dL if age > 18 years; LDL-C > 160 mg/dL if age < 18 years) and compared patients with a pathogenic mutation with those without an identified pathogenic mutation.

RESULTS

We studied 179 patients with mutation+ FH and 147 with mutation- FH. The mean age was 44 (± 18) years. The lipid profile was more atherogenic in those with mutation+ FH, who had higher LDL-C (254 ± 69 mg/dL vs 218 ± 35 mg/dL; P < 0.01) and lower HDL-C (53 ± 14 mg/dL vs 58 ± 17 mg/dL; P < 0.01). Despite the more atherogenic nonlipid cardiovascular profile of patients with mutation- FH, the age of CHD onset was earlier in patients with mutation+ FH (48 vs 56 years; P = 0.026). After multiple adjustment, the presence of a positive mutation was significantly associated with premature CHD (OR: 3.0, 95% CI: 1.38-6.55, P < 0.01).

CONCLUSIONS

Patients with mutation+ FH have a more atherogenic lipid profile and a 3-fold higher risk of premature CHD, as well as earlier onset of CHD, than patients with mutation- FH.

How to implement clinical guidelines to optimise familial hypercholesterolaemia diagnosis and treatment

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) is a genetic disorder associated with significantly elevated plasma low-density lipoprotein cholesterol (LDL-C) and premature coronary heart disease (CHD). Optimal management of FH relies on early identification and treatment with statins alone or in combination with other lipid-lowering therapies. A lack of awareness of FH and its manifestations among primary care physicians and specialists has led to many individuals being misdiagnosed in the early stages of the disease, further increasing the risk of CHD and requiring much more intensive lipid-lowering strategies. Therefore, implementing clinical guidelines to optimise the diagnosis and treatment of FH is essential.

METHODS

A working group of clinical experts managing FH patients in their daily practice collaborated in order to provide healthcare professionals with a practical evidence-based guide to streamline early diagnosis and treatment of FH.

RESULTS

Following thorough evaluation of available data and clinical guidelines, the expert working group provided recommendations on how to detect patients with a suspicion of FH; criteria for clinical and genetic diagnoses of FH; how to assess atherosclerosis in primary care and identify patients at the highest risk; follow-up approaches for patients' families; the most optimal treatment combinations; and when to start lipid-lowering therapy in children with FH.

CONCLUSIONS

The expert working group placed great importance on an individualised approach in the management of FH and highlighted the unmet need for both improved education and communication with the laboratory for physicians when LDL-C levels are significantly elevated. Screening high-risk individuals, or cascade screening, is the most cost-effective way of identifying FH cases and initiating adequate statin therapy alone or in combination with other lipid-lowering therapies. In the case of severe FH, where plasma LDL-C levels remain high following maximum-tolerated statin and ezetimibe treatment, PCSK9 inhibitors should be considered.

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) (&gt;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.

Statin wars: have we been misled about the evidence? A narrative review

Statins are the most widely prescribed, cholesterol-lowering drugs in the world. Despite the expiration of their patents, revenue for statins is expected to rise, with total sales on track to reach an estimated US$1 trillion by 2020. A bitter dispute has erupted among doctors over suggestions that statins should be prescribed to millions of healthy people at low risk of heart disease. There are concerns that the benefits have been exaggerated and the risks have been underplayed. Also, the raw data on the efficacy and safety of statins are being kept secret and have not been subjected to scrutiny by other scientists. This lack of transparency has led to an erosion of public confidence. Doctors and patients are being misled about the true benefits and harms of statins, and it is now a matter of urgency that the raw data from the clinical trials are released.

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.

From public health genomics to precision public health: a 20-year journey

In this paper, we review the evolution of the field of public health genomics in the United States in the past two decades. Public health genomics focuses on effective and responsible translation of genomic science into population health benefits. We discuss the relationship of the field to the core public health functions and essential services, review its evidentiary foundation, and provide examples of current US public health priorities and applications. We cite examples of publications to illustrate how Genetics in Medicine reflected the evolution of the field. We also reflect on how public-health genomics is contributing to the emergence of "precision public health" with near-term opportunities offered by the US Precision Medicine (AllofUs) Initiative.

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.

The Genetic Spectrum of Familial Hypercholesterolemia (FH) in the Iranian Population

Familial hypercholesterolemia (FH) is an autosomal dominant disorder associated with premature cardiovascular disease (CVD). Mutations in the LDLR, APOB, and PCSK9 genes are known to cause FH. In this study, we analysed the genetic spectrum of the disease in subjects from the Iranian population with a clinical diagnosis of FH. Samples were collected from 16 children and family members from five different cities of Iran. Probands were screened for mutations in the LDLR, APOB, and PCSK9 genes using next generation sequencing, with results confirmed by Sanger sequencing. The likely pathology of identified variants was examined using in silico tools. Of the probands, 14 had a clinical diagnosis of homozygous FH and two of heterozygous FH. No mutations were found in either APOB or PCSK9, but nine probands were homozygous for seven different LDLR mutations, with p.(Trp577Arg) occurring in three and p.Val806Glyfs*11 occurring in two patients. Two mutations were novel: p.(Leu479Gln) and p.(Glu668*). Seven probands with a clinical diagnosis of FH were mutation negative. This pilot study, integrating clinical and molecular-based techniques, begins to elucidate the FH heterogeneity and the mutation spectrum in the Iranian population. Such information is important for future disease management and cost savings.

Persistent High Non-High-Density Lipoprotein Cholesterol in Early Childhood: A Latent Class Growth Model Analysis

OBJECTIVES

To examine patterns of non-high-density lipoprotein (HDL) cholesterol in early childhood and identify factors associated with persistent high non-HDL cholesterol in healthy urban children.

STUDY DESIGN

We identified all children enrolled in a primary care practice-based research network called TARGet Kids! (The Applied Research Group for Kids) with ≥3 laboratory measurements of non-HDL cholesterol. Latent class growth model analysis was performed to identify distinct trajectory groups for non-HDL cholesterol. Trajectory groups were then categorized into "normal" vs "persistent-high" non-HDL cholesterol based on guideline cut-off values and logistic regression was completed to examine the association between trajectory group and the presence of anthropometric and cardiometabolic risk factors.

RESULTS

A total of 608 children met inclusion criteria for the trajectory analysis (median age at enrolment = 18.3, IQR = 27.9 months). Four trajectory groups were identified with 2 groups (n = 451) categorized as normal non-HDL cholesterol and 2 groups (n = 157) as persistent high non-HDL cholesterol. Family history of high cholesterol (OR 2.04, 95% CI 1.27-3.28) was associated significantly with persistent high non-HDL cholesterol, whereas East/Southeast Asian vs European ethnicity (OR 0.33, 95% CI 0.14-0.78), longer breastfeeding duration (OR 0.96, 95% CI 0.93-1.00), and greater birth weight (OR 0.69, 95% CI 0.48-1.00) were associated with lower odds of persistent high non-HDL cholesterol.

CONCLUSIONS

Patterns of non-HDL cholesterol are identified during early childhood, and family history of high cholesterol was associated most strongly with persistent high non-HDL cholesterol. Future research should inform the development of a clinical prediction tool for lipids in early childhood to identify children who may benefit from interventions to promote cardiovascular health.

Evaluation of reported pathogenic variants and their frequencies in a Japanese population based on a whole-genome reference panel of 2049 individuals

Clarifying allele frequencies of disease-related genetic variants in a population is important in genomic medicine; however, such data is not yet available for the Japanese population. To estimate frequencies of actionable pathogenic variants in the Japanese population, we examined the reported pathological variants in genes recommended by the American College of Medical Genetics and Genomics (ACMG) in our reference panel of genomic variations, 2KJPN, which was created by whole-genome sequencing of 2049 individuals of the resident cohort of the Tohoku Medical Megabank Project. We searched for pathogenic variants in 2KJPN for 57 autosomal ACMG-recommended genes responsible for 26 diseases and then examined their frequencies. By referring to public databases of pathogenic variations, we identified 143 reported pathogenic variants in 2KJPN for the 57 ACMG recommended genes based on a classification system. At the individual level, 21% of the individuals were found to have at least one reported pathogenic allele. We then conducted a literature survey to review the variants and to check for evidence of pathogenicity. Our results suggest that a substantial number of people have reported pathogenic alleles for the ACMG genes, and reviewing variants is indispensable for constructing the information infrastructure of genomic medicine for the Japanese population.

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.

Reverse cascade screening for familial hypercholesterolemia in high-risk Chinese families

BACKGROUND

Reverse cascade screening is not commonly employed to detect new cases of familial hypercholesterolemia (FH). We aimed to assess the outcome of this screening strategy in families in which the probands were children with severe FH.

HYPOTHESIS

Reverse cascade screening is an effective method to detect new patients with FH.

METHODS

Reverse cascade screening was undertaken starting from 47 index children with severe hypercholesterolemia; 39 were homozygous/compound heterozygous FH and 8 were heterozygous FH. Available parents, siblings, and second-degree relatives were contacted and screened.

RESULTS

From the 39 cases of homozygous/compound heterozygous FH, 80 first-degree family members were available for screening; 70 were parents and 10 were siblings. All first-degree relatives screened were genetically diagnosed with FH. None of the parents had been treated with statins at the time of diagnosis, and 10 (12.7%) had premature coronary artery disease. Additionally, 46 second-degree relatives were screened, of which 41 (89%) were diagnosed with FH. From the 8 heterozygous FH children, 17 first- and second-degree relatives were screened and 12 new cases of FH were also diagnosed. Hence, the overall diagnostic yield of screening was 2.8 new cases of FH per index case.

CONCLUSIONS

Reverse cascade screening is a highly effective method for diagnosing new cases of FH in parents, siblings, and second-degree relatives of index children with severe FH.

Use of next-generation sequencing to detect LDLR gene copy number variation in familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a heritable condition of severely elevated LDL cholesterol, caused predominantly by autosomal codominant mutations in the LDL receptor gene (LDLR). In providing a molecular diagnosis for FH, the current procedure often includes targeted next-generation sequencing (NGS) panels for the detection of small-scale DNA variants, followed by multiplex ligation-dependent probe amplification (MLPA) in LDLR for the detection of whole-exon copy number variants (CNVs). The latter is essential because ∼10% of FH cases are attributed to CNVs in LDLR; accounting for them decreases false negative findings. Here, we determined the potential of replacing MLPA with bioinformatic analysis applied to NGS data, which uses depth-of-coverage analysis as its principal method to identify whole-exon CNV events. In analysis of 388 FH patient samples, there was 100% concordance in LDLR CNV detection between these two methods: 38 reported CNVs identified by MLPA were also successfully detected by our NGS method, while 350 samples negative for CNVs by MLPA were also negative by NGS. This result suggests that MLPA can be removed from the routine diagnostic screening for FH, significantly reducing associated costs, resources, and analysis time, while promoting more widespread assessment of this important class of mutations across diagnostic laboratories.

Newborn Thyroid Screening: Influence of Pre-Analytic Variables on Dried Blood Spot Thyrotropin Measurement

BACKGROUND

Measuring thyrotropin (TSH) eluted from a dried blood spot (DBS) is used to screen an estimated 30 million newborns annually for congenital hypothyroidism (CH). Newborn thyroid screening has eliminated cretinism from the industrialized world and decreased the adverse effects of unrecognized CH on neurocognitive development. Hematocrit, a pre-analytic variable that affects the measurement of TSH from a DBS, contributes to the imprecision of DBS TSH measurement and could account for false-negative and false-positive DBS newborn screening test results. To assess whether variations in hematocrit found in newborns have a clinical effect in DBS-based newborn thyroid screening, the effects of hematocrit variability on the measurement of DBS TSH were studied.

METHODS

U.S. Centers for Disease Control and Prevention procedures for manufacturing DBS performance testing standards were used to generate DBSs from blood samples, with hematocrits of 35%, 40%, 45%, 50%, 55%, 60%, and 65% and serum TSH concentrations of 6.3 ± 0.4 and 26.6 ± 8.0 mIU/L. TSH was measured in the eluates of four replicate DBS 3 mm punches at each hematocrit using the Thailand Ministry of Public Health Newborn Screening Operation Center enzyme-linked immunosorbent assay. Data were analyzed using a linear mixed-effects model.

RESULTS

Based on the mixed-effects model, hematocrit significantly affected DBS TSH measurement (p < 0.001). A 1% increase in hematocrit resulted in a 0.06 mIU/L decrease in eluate TSH when TSH was 6.3 + 0.4 mIU/L, and a 0.21 mIU/L decrease in eluate TSH when TSH was 26.6 + 8.0 mIU/L.

CONCLUSIONS

DBS TSH is significantly affected by the blood sample hematocrit. The pre-analytic variability due to hematocrit is independent of TSH assay sensitivity, specificity, precision, repeatability, and reference intervals. The effect of hematocrit on DBS TSH measurement is clinically relevant, could account for geographic and ethnic variation in the incidence of CH, and may result in both false-positive and false-negative CH screening results. Individual newborn and population-specific hematocrit correction factors may improve the precision of DBS TSH measurement.

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.

Molecular diagnosis of familial hypercholesterolaemia

PURPOSE OF REVIEW

Familial hypercholesterolaemia is a hereditary disorder of lipoprotein metabolism which causes a lifelong increase in LDL-C levels resulting in premature coronary heart disease. The present review looks at some of the recent literature on how molecular methods can be used to assist in the definitive diagnosis of familial hypercholesterolaemia in a range of patient groups.

RECENT FINDINGS

Several recent studies have shown that the prevalence of clinical familial hypercholesterolaemia is higher than previously thought at 1/200 to 1/300, and that 2-5% of patients presenting with early myocardial infarction can be found to have a familial hypercholesterolaemia mutation. The present review then examines different approaches to molecular testing for familial hypercholesterolaemia including point mutation panels versus next-generation sequencing gene panels, and the range of genes tested by some of those panels. Finally, we review the recent evidence for polygenic hypercholesterolaemia within clinically defined familial hypercholesterolaemia patient populations.

SUMMARY

To identify patients with familial hypercholesterolaemia within clinically selected patient groups efficiently, a clinical scoring system should be combined with a molecular testing approach for mutations and for polygenic LDL-C single-nucleotide polymorphisms. Alternatively, a population screening methodology may be appropriate, using mutation testing at an early age before significant atherosclerosis has begun. The precise molecular testing method chosen may depend on the clinical presentation of the patient, and/or the population from which they arise.

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.

Cardiovascular Risk Assessment

Cardiovascular risk assessment is fundamental to prevention of cardiovascular disease, because it helps determine the size of the potential benefits that might accrue to individual patients from use of statins, aspirin, and other preventive interventions. Current guidelines recommend specific algorithms for cardiovascular risk assessment that combine information from traditional risk factors including blood pressure, lipids, and smoking, along with age and sex and other factors. These algorithms are the subject of active research and controversy. This article addresses the rationale, current guidelines and use, and potential future directions of cardiovascular risk assessment.

Prevention of cardiovascular disease in patients with familial hypercholesterolaemia: The role of PCSK9 inhibitors

Familial hypercholesterolaemia is an autosomal dominant inherited disorder characterised by elevated low-density lipoprotein cholesterol levels and consequently an increased risk of atherosclerotic cardiovascular disease (ASCVD). Familial hypercholesterolaemia is relatively common, but is often underdiagnosed and undertreated. Cardiologists are likely to encounter many individuals with familial hypercholesterolaemia; however, patients presenting with premature ASCVD are rarely screened for familial hypercholesterolaemia and fasting lipid levels are infrequently documented. Given that individuals with familial hypercholesterolaemia and ASCVD are at a particularly high risk of subsequent cardiac events, this is a missed opportunity for preventive therapy. Furthermore, because there is a 50% chance that first-degree relatives of individuals with familial hypercholesterolaemia will also be affected by the disorder, the underdiagnosis of familial hypercholesterolaemia among patients with ASCVD is a barrier to cascade screening and the prevention of ASCVD in affected relatives. Targeted screening of patients with ASCVD is an effective strategy to identify new familial hypercholesterolaemia index cases. Statins are the standard treatment for individuals with familial hypercholesterolaemia; however, low-density lipoprotein cholesterol targets are not achieved in a large proportion of patients despite treatment. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have been shown to reduce low-density lipoprotein cholesterol levels considerably in individuals with familial hypercholesterolaemia who are concurrently receiving the maximal tolerated statin dose. The clinical benefit of PCSK9 inhibitors must, however, also be considered in terms of their cost-effectiveness. Increased awareness of familial hypercholesterolaemia is required among healthcare professionals, particularly cardiologists and primary care physicians, in order to start early preventive measures and to reduce the mortality and morbidity associated with familial hypercholesterolaemia and ASCVD.

How many familial hypercholesterolemia patients are eligible for PCSK9 inhibition?

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a high cardiovascular risk condition. Less than 20% of patients achieve the LDL targets. Although PCSK9 inhibitors improve control and reduce cardiovascular events, official recommendations for their use are restrictive. We aim to assess the number of FH patients suitable for PCSK9 inhibition according to the European guidelines.

METHODS

A total of 2685 FH patients, with a minimum follow-up of 6 months, included in the Dyslipidemia Registry of the Spanish Arteriosclerosis Society, were sorted according to the intensity of their lipid-lowering therapy (LLT) and LDL cholesterol levels achieved. The number of patients who met the recommendations for PCSK9 inhibition treatment according to the European Atherosclerosis Society (ESC/EAS), Spanish Arteriosclerosis Society and the European Medicines Agency was calculated.

RESULTS

In total, 1573 patients were on high-intensity LLT; 607 were on moderate-intensity statins; 82 were on low-intensity LLT, and 423 were neither on statins nor on ezetimibe in the last visit registered. The mean LDL reduction among those on high-intensity LLT was 54%. Ninety-one percent of patients on high-intensity LLT had an LDL below 5.2 mmol/L, 53% below 3.4 mmol/L, and 23% below 2.6 mmol/L. Only 12% of FH patients with cardiovascular disease achieved 1.8 mmol/L. Despite this, only 17% of patients qualified for PCSK9 inhibition according to ESC/EAS guidelines.

CONCLUSIONS

For patients with a condition that exposes them to high cardiovascular risk and who have extreme difficulties in achieving LDL targets, wider access to PCSK9 inhibitor therapy is warranted.

Screening for familial hypercholesterolaemia in childhood: Avon Longitudinal Study of Parents and Children (ALSPAC)

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) is an autosomal-dominant disease with frequency of 1/500 to 1/250 that leads to premature coronary heart disease. New approaches to identify FH mutation-carriers early are needed to prevent premature cardiac deaths. In a cross-sectional study of the Avon Longitudinal Study of Parents and Children (ALSPAC), we evaluated the biochemical thresholds for FH screening in childhood, and modelled a two-stage biochemical and sequencing screening strategy for FH detection.

METHODS

From 5083 ALSPAC children with cholesterol measurement at age nine years, FH genetic diagnosis was performed in 1512 individuals, using whole-genome or targeted sequencing of known FH-causing genes. Detection rate (DR) and false-positive rate (FPR) for proposed screening thresholds (total-cholesterol > 1.53, or LDL-C > 1.84 multiples of the median (MoM)) were assessed.

RESULTS

Six of 1512 sequenced individuals had an FH-causing mutation of whom five had LDL-C > 1.84 MoM, giving a verification-bias corrected DR of 62.5% (95% CI: 25-92), with a FPR of 0.2% (95% CI: 0.1-0.4). The DR for the TC cut-point of 1.53 MoM was 25% (95% CI: 3.2-65.1) with a FPR of 0.4% (95% CI: 0.2-0.6). We estimated 13 of an expected 20 FH mutation carriers (and 13 of the 20 parental carriers) could be detected for every 10,000 children screened, with false-positives reliably excluded by addition of a next generation sequencing step in biochemical screen-positive samples.

CONCLUSIONS

Proposed cholesterol thresholds for childhood FH screening were less accurate than previously estimated. A sequential strategy of biochemical screening followed by targeted sequencing of FH genes in screen-positive children may help mitigate the higher than previously estimated FPR and reduce wasted screening of unaffected parents.