LDLR variant classification for improved cardiovascular risk prediction in familial hypercholesterolemia.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is a genetic disorder marked by high LDL cholesterol and an increased premature coronary artery disease (CAD) risk. Current dichotomous classification of LDL receptor gene (LDLR) variants may inadequately capture patient variability in LDL cholesterol levels and CAD risk. This study assessed a novel approach for determining LDLR variant severity using variant-specific LDL cholesterol percentiles. METHODS: Participants of the Dutch FH cascade screening program were screened for 456 LDLR variants. For each LDLR variant carrier, a sex- and age-specific LDL cholesterol percentile was derived from the LDL cholesterol level measured at study entry, i.e. generally from the blood drawn for DNA analysis. These percentiles were used to calculate the mean LDL cholesterol percentile for each variant. Based on the variant-specific LDL cholesterol percentiles, carriers were grouped into the following LDL cholesterol strata: <75th, 75th-88th, 88th-92nd, 92nd-96.5th, 96.5th-98th, and ≥98th percentile. Additionally, variants were categorized into class 1 (LDLR deficient) and non-class 1 (often LDLR defective) variants. CAD risk between carriers in the different LDL cholesterol strata and non-carriers was compared using a Cox proportional hazard model. RESULTS: Out of 35,067 participants, 12,485 (36 %) LDLR variant carriers (mean age 38.0 ± 20.0 years, 47.7 % male) were identified. Carriers had a 5-fold higher CAD risk compared with non-carriers. Hazard ratios for CAD increased gradually from 2.2 (95%CI 0.97-5.0) to 12.0 (95%CI 5.5-24.8) across the LDL cholesterol strata. A 7.3-fold and 3.9-fold increased CAD risk was observed in carriers of class 1 and non-class 1 LDLR variants, respectively. CONCLUSIONS: This study presents a refined approach for classifying LDLR variants based on their impact on LDL cholesterol levels, allowing for more precise, genotype-specific CAD risk estimation in FH patients compared with traditional methods.

Familial hypercholesterolemia care by Dutch pediatricians-mind the gaps.

PURPOSE: Familial hypercholesterolemia (FH) leads to elevated low-density lipoprotein cholesterol levels, which increases the risk of premature atherosclerotic cardiovascular disease (ASCVD). Since the first functional and morphologic changes of the arterial wall occur in childhood, treatment should start early in childhood to mitigate the elevated risk of ASCVD. Pediatricians play an important role in the detection and care of children with FH. In this study, we aim to explore potential gaps in FH care amongst Dutch pediatricians, in order to enhance their knowledge and awareness of detecting and treating children with FH. METHODS: An anonymous online survey, deployed using Google Forms, including 26 closed and semi-closed questions on FH care in children was distributed by the Dutch Association of Pediatrics via a newsletter to which the majority of the practicing Dutch pediatricians subscribe. In addition, we requested that the pediatric departments of all Dutch hospitals in the Netherlands distribute this survey personally among their employed pediatricians. Respondents were instructed to answer the questions without any help or use of online resources. RESULTS: Between September 1st, 2023 and November 1st, 2023, 158 (an estimated 11% response rate) Dutch pediatricians completed the survey. They reported a median (IQR) of 15.0 (6.0-22.0) years of experience as a pediatrician, and 34 (21.5%) were working in academic hospitals. The majority (76.6%) of pediatricians correctly identified a typical FH lipid profile but 68 (43.0%) underestimated the true prevalence of FH (1:300). Underestimation and unawareness of the increased risk of FH patients for ASCVD were reported by 37.3% and 25.9% of pediatricians, respectively. Although 70.9% of the pediatricians correctly defined FH, only 67 (42.4%) selected statins and ezetimibe to treat severe hypercholesterolemia. CONCLUSIONS: The results of this study suggest significant gaps in knowledge and awareness of FH in children among Dutch pediatricians. FH care in children needs improvement through educational and training initiatives to mitigate the life-long risk of ASCVD from early life. WHAT IS KNOWN: • Familial hypercholesterolemia (FH) leads to elevated LDL-cholesterol levels, which increases the risk of premature atherosclerotic cardiovascular disease (ASCVD). • The process of atherosclerosis starts in childhood • Pediatricians play an important role in the detection and treatment of children with FH. WHAT IS NEW: • Our results highlight significant gaps in care for children with FH amongst pediatricians and this may lead to suboptimal detection and treatment. • FH care in children needs improvement by educational initiatives to ultimately prevent ASCVD in adulthood.

Enhanced identification of familial hypercholesterolemia using central laboratory algorithms.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is a highly prevalent genetic disorder resulting in markedly elevated LDL cholesterol levels and premature coronary artery disease. FH underdiagnosis and undertreatment require novel detection methods. This study evaluated the effectiveness of using an LDL cholesterol cut-off ≥99.5th percentile (sex- and age-adjusted) to identify clinical and genetic FH, and investigated underutilization of genetic testing and undertreatment in FH patients. METHODS: Individuals with at least one prior LDL cholesterol level ≥99.5th percentile were selected from a laboratory database containing lipid profiles of 590,067 individuals. The study comprised three phases: biochemical validation of hypercholesterolemia, clinical identification of FH, and genetic determination of FH. RESULTS: Of 5614 selected subjects, 2088 underwent lipid profile reassessment, of whom 1103 completed the questionnaire (mean age 64.2 ± 12.7 years, 48% male). In these 1103 subjects, mean LDL cholesterol was 4.0 ± 1.4 mmol/l and 722 (65%) received lipid-lowering therapy. FH clinical diagnostic criteria were met by 282 (26%) individuals, of whom 85% had not received guideline-recommended genetic testing and 97% failed to attain LDL cholesterol targets. Of 459 individuals consenting to genetic validation, 13% carried an FH-causing variant, which increased to 19% in clinically diagnosed FH patients. CONCLUSIONS: The identification of a substantial number of previously undiagnosed and un(der)treated clinical and genetic FH patients within a central laboratory database highlights the feasibility and clinical potential of this targeted screening strategy; both in identifying new FH patients and in improving treatment in this high-risk population.

Beyond early LDL cholesterol lowering to prevent coronary atherosclerosis in familial hypercholesterolaemia.

AIMS: Familial hypercholesterolaemia (FH) patients are subjected to a high lifetime exposure to low density lipoprotein cholesterol (LDL-C), despite use of lipid-lowering therapy (LLT). This study aimed to quantify the extent of subclinical atherosclerosis and to evaluate the association between lifetime cumulative LDL-C exposure and coronary atherosclerosis in young FH patients. METHODS AND RESULTS: Familial hypercholesterolaemia patients, divided into a subgroup of early treated (LLT initiated <25 years) and late treated (LLT initiated ≥25 years) patients, and an age- and sex-matched unaffected control group, underwent coronary CT angiography (CCTA) with artificial intelligence-guided analysis. Ninety genetically diagnosed FH patients and 45 unaffected volunteers (mean age 41 ± 3 years, 51 (38%) female) were included. Familial hypercholesterolaemia patients had higher cumulative LDL-C exposure (181 ± 54 vs. 105 ± 33 mmol/L ∗ years) and higher prevalence of coronary plaque compared with controls (46 [51%] vs. 10 [22%], OR 3.66 [95%CI 1.62-8.27]). Every 75 mmol/L ∗ years cumulative exposure to LDL-C was associated with a doubling in per cent atheroma volume (total plaque volume divided by total vessel volume). Early treated patients had a modestly lower cumulative LDL-C exposure compared with late treated FH patients (167 ± 41 vs. 194 ± 61 mmol/L ∗ years; P = 0.045), without significant difference in coronary atherosclerosis. Familial hypercholesterolaemia patients with above-median cumulative LDL-C exposure had significantly higher plaque prevalence (OR 3.62 [95%CI 1.62-8.27]; P = 0.001), compared with patients with below-median exposure. CONCLUSION: Lifetime exposure to LDL-C determines coronary plaque burden in FH, underlining the need of early as well as potent treatment initiation. Periodic CCTA may offer a unique opportunity to monitor coronary atherosclerosis and personalize treatment in FH.

This study reveals that young patients with familial hypercholesterolaemia (FH), as compared with individuals without FH, have a higher build-up of coronary artery plaque, linked directly to their increased lifetime exposure to LDL cholesterol. Genetically confirmed FH patients have a higher coronary plaque burden than those without FH, with every 75 mmol/L ∗ years increase in lifetime cumulative LDL cholesterol exposure resulting in a two-fold increase in total plaque volume. Early and potent LDL cholesterol lowering treatments are crucial for FH patients to prevent future cardiovascular diseases.

Low-Cost High-Throughput Genotyping for Diagnosing Familial Hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is a common but underdiagnosed genetic disorder characterized by high low-density lipoprotein cholesterol levels and premature cardiovascular disease. Current sequencing methods to diagnose FH are expensive and time-consuming. In this study, we evaluated the accuracy of a low-cost, high-throughput genotyping array for diagnosing FH. METHODS: An Illumina Global Screening Array was customized to include probes for 636 variants, previously classified as FH-causing variants. First, its theoretical coverage was assessed in all FH variant carriers diagnosed through next-generation sequencing between 2016 and 2022 in the Netherlands (n=1772). Next, the performance of the array was validated in another sample of FH variant carriers previously identified in the Dutch FH cascade screening program (n=1268). RESULTS: The theoretical coverage of the array for FH-causing variants was 91.3%. Validation of the array was assessed in a sample of 1268 carriers of whom 1015 carried a variant in LDLR, 250 in APOB, and 3 in PCSK9. The overall sensitivity was 94.7% and increased to 98.2% after excluding participants with variants not included in the array design. Copy number variation analysis yielded a 89.4% sensitivity. In 18 carriers, the array identified a total of 19 additional FH-causing variants. Subsequent DNA analysis confirmed 5 of the additionally identified variants, yielding a false-positive result in 16 subjects (1.3%). CONCLUSIONS: The FH genotyping array is a promising tool for genetically diagnosing FH at low costs and has the potential to greatly increase accessibility to genetic testing for FH. Continuous customization of the array will further improve its performance.

Use of Lipoprotein(a) to improve diagnosis and management in clinical familial hypercholesterolemia.

BACKGROUND AND AIMS: Lipoprotein(a) (Lp(a)) is an LDL-like particle whose plasma levels are largely genetically determined. The impact of measuring Lp(a) in patients with clinical familial hypercholesterolemia (FH) referred for genetic testing is largely unknown. We set out to evaluate the contribution of (genetically estimated) Lp(a) in a large nation-wide referral population of clinical FH. METHODS: In 1504 patients referred for FH genotyping, we used an LPA genetic instrument (rs10455872 and rs3798220) as a proxy for plasma Lp(a) levels. The genetic Lp(a) proxy was used to correct LDL-cholesterol and reclassify patients with clinical FH based on Dutch Lipid Criteria Network (DLCN) scoring. Finally, we used estimated Lp(a) levels to reclassify ASCVD risk using the SCORE and SMART risk scores. RESULTS: LPA SNPs were more prevalent among mutation-negative compared with mutation-positive patients (296/1280 (23.1%) vs 35/224 (15.6%), p = 0.016). Among patients with genetically defined high Lp(a) levels, 9% were reclassified to the DLCN category 'unlikely FH' using Lp(a)-corrected LDL-cholesterol (LDL-Ccor) and all but one of these patients indeed carried no FH variant. Furthermore, elevated Lp(a) reclassified predicted ASCVD risk into a higher category in up to 18% of patients. CONCLUSIONS: In patients referred for FH molecular testing, we show that taking into account (genetically estimated) Lp(a) levels not only results in reclassification of probability of genetic FH, but also has an impact on individual cardiovascular risk evaluation. However, to avoid missing the diagnosis of an FH variant, clear thresholds for the use of Lp(a)-cholesterol adjusted LDL-cholesterol levels in patients referred for genetic testing of FH must be established.

Beyond the Usual Suspects: Expanding on Mutations and Detection for Familial Hypercholesterolemia.

Introduction: Familial hypercholesterolemia (FH) is a highly prevalent condition, predisposing individuals to premature cardiovascular disease and with a genetic basis more complex than initially thought. Advances in molecular technologies have provided novel insights into the role of next-generation-sequencing, the assessment and classification of newly found variants, the complex genotype-phenotype correlation, and the position of FH in the context of other dyslipidaemias.Areas covered: Understanding the scope of genetic determinants of FH has expanded substantially. This article reviews the current literature on the complexity that comes with this incremental knowledge and highlights the added value of genetic testing as an addition to phenotypic diagnosis of FH. Moreover, we discuss the broad genetic basis of FH, with a focus on the three main FH genes, but we also pay attention to polygenic hypercholesterolemia as well as minor and modulator genes involved in FH.Expert opinion: Both the availability and the need for genetic analysis of FH are on the rise as costs of sequencing continue to drop and new therapies require a genetic diagnosis for reimbursement. However, greater use of genetic testing requires more education of healthcare professionals, since molecular technologies will allow for rapid and accurate evaluation of large numbers of detected variants.

Advances, gaps and opportunities in the detection of familial hypercholesterolemia: overview of current and future screening and detection methods.

PURPOSE OF REVIEW: Studies reaffirm that familial hypercholesterolemia is more prevalent than initially considered, with a population frequency of approximately one in 300. The majority of patients remains unidentified. This warrants critical evaluation of existing screening methods and exploration of novel methods of detection. RECENT FINDINGS: New public policy recommendations on the detection of familial hypercholesterolemia have been made by a global community of experts and advocates. Phenotypic tools for diagnosing index cases remain inaccurate. Genetic testing is the gold standard for familial hypercholesterolemia and a new international position statement has been published. Correction of LDL cholesterol (LDL-C) for the cholesterol content of lipoprotein(a) [Lp(a)] may increase the precision of the phenotypic diagnosis of familial hypercholesterolemia. Cascade cotesting for familial hypercholesterolemia and elevated Lp(a) levels provides a new opportunity to stratify risk in families. Digital technology and machine learning methods, coupled with clinical alert and decision support systems, lead the way in more efficient approaches for detecting and managing index cases. Universal screening of children, combined with child-parent cascade testing, appears to be the most effective method for underpinning a population strategy for maximizing the detection of familial hypercholesterolemia. SUMMARY: Detection of familial hypercholesterolemia can be enhanced by optimizing current diagnostic algorithms, probing electronic health records with novel information technologies and integrating universal screening of children with cascade testing of parents and other relatives.

Electronic health records to facilitate continuous detection of familial hypercholesterolemia.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is an inherited disorder associated with increased risk of coronary heart disease as a result of high LDL-cholesterol (LDL-C). The clinical diagnosis can be made with the Dutch Lipid Clinic Network criteria (DLCN criteria). FH is an underdiagnosed disorder, possibly due to false negative LDL-C interpretation during lipid lowering therapy (LLT). We hypothesized that automated health record-based integration of data can provide a signal to facilitate identification of FH patients. METHODS: We included patients with LDL-C ≥6.5 mmol/l after correction for LLT in all patients testing LDL-C in Northwest Clinics, The Netherlands. Patients previously diagnosed with FH were excluded. The primary endpoint was the additional number of patients with DLCN criteria ≥6 points after correction for LLT. Secondary endpoints were the additional number of patients with DLCN criteria ≥6 points after also adding data on patient- and family history, and LDL-C before and after correction for LLT. Analysis was performed in a daily automated routine (HiX ChipSoft). RESULTS: In a total of 41,937 individual LDL-C measurements during 26 weeks, we found 351 patients with LDL-C ≥6.5 mmol/l after automated correction for LLT. FH had previously been diagnosed in 42 patients. In the remaining 309 patients (58.3% female; age: 66 ± 11 yrs (mean ± SD); 85.8% on LLT), the number of patients with DLCN criteria ≥6 points increased from 9 to 95 after correction for LLT, and to 127 after also adding patient and family history. The mean LDL-C before and after correction for LLT was 4.69 ± 1.42 mmol/l and 8.16 ± 1.68 mmol/l, respectively (mean ± SD; p < 0.001). CONCLUSIONS: We conclude that automated medical record-based integration of LDL-C, LLT and patient- and family history can provide a crucial signal to facilitate identification of FH. Whether this signal results in subsequent genetic identification of FH patients and their relatives requires further study.