What Is the Prevalence of Familial Hypercholesterolemia?

A Rapid and Scalable Multiplex PCR-Based Next-Generation Amplicon Sequencing Method for Familial Hypercholesterolemia Genetic Screening

BACKGROUND

Familial hypercholesterolemia (FH) is a frequently underdiagnosed genetic disorder characterized by elevated low-density lipoprotein (LDL) levels. Genetic testing of LDLR, APOB, and PCSK9 genes can identify variants in up to 80% of clinically diagnosed patients. However, limitations in time, scalability, and cost have hindered effective next-generation sequencing of these genes. Additionally, pharmacogenomic variants are associated with statin-induced adverse effects in FH patients. To address these challenges, we developed a multiplex primer-based amplicon sequencing approach for FH genetic testing.

METHODS

Multiplex primers were designed for the exons of the LDLR, APOB, and PCSK9 genes, as well as for pharmacogenomic variants rs4149056 (SLCO1B1:c.521T > A), rs2306283 (SLCO1B1:c.388A > G), and rs2231142 (ABCG2:c.421C > A). Analytical validation using samples with known pathogenic variants and clinical validation with 12 FH-suspected probands were conducted. Library preparation was based on a bead-based tagmentation method, and sequencing was conducted on the NovaSeq 6000 platform.

RESULTS

Our approach ensured no amplicon dropouts, with over 100× coverage on each amplicon. Known variants in 2 samples were successfully detected. Further, we identified one heterozygous LDLR (p.Glu228Ter) variant and 2 homozygous cases of LDLR (p.Lys294Ter) and LDLR (p.Ser177Leu) variants in patients. Pharmacogenomic analysis revealed that overall 3 patients may require reduced statin doses. Our approach offered reduced library preparation time (approximately 3 h), greater scalability, and lower costs (under $50) for FH genetic testing.

CONCLUSIONS

Our method effectively sequences LDLR, APOB, and PCSK9 genes including pharmacogenomic variants that will guide appropriate screening and statin dosing, thus increasing both efficiency and affordability.

Consensus document on diagnosis and management of familial hypercholesterolemia from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

Familial Hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism that causes an increased risk of premature atherosclerotic cardiovascular disease (ASCVD). Although early diagnosis and treatment of FH can significantly improve the cardiovascular prognosis, this disorder is underdiagnosed and undertreated. For these reasons the Italian Society for the Study of Atherosclerosis (SISA) assembled a Consensus Panel with the task to provide guidelines for FH diagnosis and treatment.

DATA SYNTHESIS

Our guidelines include: i) an overview of the genetic complexity of FH and the role of candidate genes involved in LDL metabolism; ii) the prevalence of FH in the population; iii) the clinical criteria adopted for the diagnosis of FH; iv) the screening for ASCVD and the role of cardiovascular imaging techniques; v) the role of molecular diagnosis in establishing the genetic bases of the disorder; vi) the current therapeutic options in both heterozygous and homozygous FH. Treatment strategies and targets are currently based on low-density lipoprotein cholesterol (LDL-C) levels, as the prognosis of FH largely depends on the magnitude of LDL-C reduction achieved by lipid-lowering therapies. Statins with or without ezetimibe are the mainstay of treatment. Addition of novel medications like PCSK9 inhibitors, ANGPTL3 inhibitors or lomitapide in homozygous FH results in a further reduction of LDL-C levels. LDL apheresis is indicated in FH patients with inadequate response to cholesterol-lowering therapies.

CONCLUSION

FH is a common, treatable genetic disorder and, although our understanding of this disease has improved, many challenges still remain with regard to its identification and management.

Reproductive Carrier Screening: Identifying Families at Risk for Familial Hypercholesterolemia in the United States

BACKGROUND

Familial hypercholesterolemia is a treatable genetic condition but remains underdiagnosed. We reviewed the frequency of pathogenic or likely pathogenic (P/LP) variants in the LDLR gene in female individuals receiving reproductive carrier screening.

METHODS

This retrospective observational study included samples from female patients (aged 18-55 years) receiving a 274-gene carrier screening panel from January 2020 to September 2022. LDLR exons and their 10 base pair flanking regions were sequenced. Carrier frequency for P/LP variants was calculated for the entire population and by race/ethnicity. The most common variants and their likely functional effects were evaluated.

RESULTS

A total of 91 637 tests were performed on women with race/ethnicity reported as Asian (8.8%), Black (6.1%), Hispanic (8.5%), White (29.0%), multiple or other (15.0%), and missing (33.0%). Median age was 32.8 years with 83 728 (91%) <40 years. P/LP LDLR variants were identified in 283 samples (1 in 324). No patients were identified with >1 P/LP variant. LDLR carrier frequency was higher in Asian (1 in 191 [95% CI, 1 in 142-258]) compared with White (1 in 417 [95% CI, 1 in 326-533]; P<0.001) or Black groups (1 in 508 [95% CI, 1 in 284-910]; P=0.004). The most common variants differed between populations. Of all variants, at least 25.0% were predicted as null variants.

CONCLUSIONS

P/LP variants in LDLR are common. Expanding the use of reproductive carrier screening to include genes associated with FH presents another opportunity to identify people predisposed to cardiovascular disease.

Population screening shows risk of inherited cancer and familial hypercholesterolemia in Oregon

The Healthy Oregon Project (HOP) is a statewide effort that aims to build a large research repository and influence the health of Oregonians through providing no-cost genetic screening to participants for a next-generation sequencing 32-gene panel comprising genes related to inherited cancers and familial hypercholesterolemia. This type of unbiased population screening can detect at-risk individuals who may otherwise be missed by conventional medical approaches. However, challenges exist for this type of high-throughput testing in an academic setting, including developing a low-cost high-efficiency test and scaling up the clinical laboratory for processing large numbers of samples. Modifications to our academic clinical laboratory including efficient test design, robotics, and a streamlined analysis approach increased our ability to test more than 1,000 samples per month for HOP using only one dedicated HOP laboratory technologist. Additionally, enrollment using a HIPAA-compliant smartphone app and sample collection using mouthwash increased efficiency and reduced cost. Here, we present our experience three years into HOP and discuss the lessons learned, including our successes, challenges, opportunities, and future directions, as well as the genetic screening results for the first 13,670 participants tested. Overall, we have identified 730 pathogenic/likely pathogenic variants in 710 participants in 24 of the 32 genes on the panel. The carrier rate for pathogenic/likely pathogenic variants in the inherited cancer genes on the panel for an unselected population was 5.0% and for familial hypercholesterolemia was 0.3%. Our laboratory experience described here may provide a useful model for population screening projects in other states.

Metabolic syndrome predicts cardiovascular risk and mortality in familial hypercholesterolemia

BACKGROUND

The association between familial hypercholesterolemia (FH) and premature atherosclerotic cardiovascular disease (ASCVD) is well established. Several risk factors other than the cumulative low-density lipoprotein cholesterol (LDL-C) have been shown to modulate the severity of the phenotype in these patients. However, the effect of the metabolic syndrome (MetS) on ASCVD risk in FH remains to be determined.

OBJECTIVES

The objective was to study the association between the presence of MetS and the incidence of different ASCVD endpoints and all-cause mortality.

METHODS

This prospective follow up study used data from 5 independent FH cohorts from Europe and North America. We analysed data of 2401 adult heterozygous FH without history of a prior ASCVD event (21,139 person-years of follow-up). Multivariate Cox proportional hazards regression was used to estimate the association between MetS and the incidence of the different endpoints.

RESULTS

The prevalence of MetS was 14% in the study population. The presence of MetS was a significant predictor of incident 10-year ASCVD after adjustment for traditional cardiovascular risk factors (HR 2.07, 95% CI 1.34-3.19), as well as of 10-year major adverse cardiovascular event (MACE) (HR 4.59, 95% CI 2.27-9.30), 10-year myocardial infarction (MI) (HR 4.29, 95% CI 1.91-9.63), and 30-year all-cause mortality (HR 4.87, 95% CI 1.99-11.89).

CONCLUSION

Our findings suggests that FH patients with MetS, have an increased cardiovascular risk that is independent from LDL-C and other traditional risk factors. Future studies are required to determine the most appropriate strategy to reduce the cardiovascular burden associated with MetS in this population.

A mixed methods study of the awareness and management of familial hypercholesterolaemia in Irish general practice

Introduction

Familial Hypercholesterolemia (FH) is one of the most common genetic disorders, with an estimated global prevalence of 1:200-500, which leads to premature cardiovascular disease. Nevertheless, public and professional awareness of FH is often lacking, with an estimated 20,000 largely undiagnosed cases in Ireland.

Purpose

The overall aim of the project was to test the feasibility of a model of care that would include electronic record screening, clinical assessment, and coding of possible FH patients across a network of general practices in Ireland. In addition, a secondary aim was to gauge the awareness and knowledge of FH across the network.

Methods

This study took part in multiple phases, employing a mixed methods design. The study included a validated questionnaire, tailored online educational resources, a retrospective chart review of patients with a history of elevated LDL cholesterol (LDLc) and an active review with a selection of those patients. Results were analyzed using SPSS V27, where descriptive statistics and relevant correlation tests were employed.

Results

Eighteen general practices agreed to take part in the study. In the initial survey, respondents rated their personal and practice familiarity with FH as slightly below average. Around one-third of respondents were not aware of FH guidelines. Of over 55,000 adult patient records searched, only 0.2% had a recorded FH diagnosis and 3.9% had ever had an LDLc above 4.9 mmol/l. Eight practices completed 198 chart reviews. Among these, 29.8% of patients had a family history recorded, and 22.2% had a family history of CVD recorded. Female patients had higher averages for highest and recent LDLc. Seventy patients underwent a clinical review-with 27% of these patients identified as "probable" or "definite FH." There was a statistically significant (p = 0.002) relationship between FH status and whether the patient had other CVD risk factors.

Conclusion

General practitioners in Ireland had similar levels of awareness of FH compared to findings from elsewhere. The activities discussed encouraged clinicians to consider FH when talking to their patients, especially those with elevated LDLc at an early age. Broader awareness of the condition could increase conversations about FH and benefit patient outcomes.

Current causes of death in familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is a codominant autosomal disease characterized by high low-density lipoprotein cholesterol (LDLc) and a high risk of premature cardiovascular disease (CVD). The molecular bases have been well defined, and effective lipid lowering is possible. This analysis aimed to study the current major causes of death of genetically defined heterozygous familial hypercholesterolemia (heFH).

METHODS

A case‒control study was designed to analyse life-long mortality in a group of heFH and control families. Data from first-degree family members of cases and controls (nonconsanguineous cohabitants), including deceased relatives, were collected from a questionnaire and review of medical records. Mortality was compared among heFH patients, nonheFH patients, and nonconsanguineous family members.

RESULTS

A total of 813 family members were analysed, 26.4% of whom were deceased. Among the deceased, the mean age of death was 69.3 years in heFH individuals, 73.5 years in nonheFH individuals, and 73.2 years in nonconsanguineous individuals, without significant differences. CVD was the cause of death in 59.7% of heFH individuals, 37.7% of nonheFH individuals, and 37.4% of nonconsanguineous individuals (P = 0.012). These differences were greater after restricting the analyses to parents. The hazard ratio of dying from CVD was 2.85 times higher (95% CI, (1.73-4.69) in heFH individuals than in individuals in the other two groups (non-FH and nonconsanguineous), who did not differ in their risk.

CONCLUSIONS

CVD mortality in heFH individuals is lower and occurs later than that described in the last century but is still higher than that in non-FH individuals. This improved prognosis of CVD risk is not associated with changes in non-CVD mortality.