Genetic basis of hypercholesterolemia in adults

Recognition and management of persistent chylomicronemia: A joint expert clinical consensus by the National Lipid Association and the American Society for Preventive Cardiology

Extreme hypertriglyceridemia, defined as triglyceride (TG) levels ≥1000 mg/dL, is almost always indicative of chylomicronemia. The current diagnostic approach categorizes individuals with chylomicronemia into familial chylomicronemia syndrome (FCS; prevalence 1-10 per million), caused by the biallelic combination of pathogenic variants that impair the lipolytic action of lipoprotein lipase (LPL), or multifactorial chylomicronemia syndrome (MCS, 1 in 500). A pragmatic framework should emphasize the severity of the phenotype and the risk of complications. Therefore, we endorse the term "persistent chylomicronemia" defined as TG ≥1000 mg/dL in more than half of the measurements to encompass patients with the highest risk for pancreatitis, regardless of their genetic predisposition. We suggest classification of PC into four subtypes: 1) genetic FCS, 2) clinical FCS, 3) PC with "alarm" features, and 4) PC without alarm features. Although patients with FCS most likely have PC, the vast majority with PC do not have genetic FCS. Proposed alarm features are: (a) history of recurrent TG-induced acute pancreatitis, (b) recurrent hospitalizations for severe abdominal pain without another identified cause, (c) childhood pancreatitis, (d) family history of TG-induced pancreatitis, and/or (e) post-heparin LPL activity <20 % of normal value. Alarm features constitute the strongest risk factors for future acute pancreatitis risk. Patients with PC and alarm features have very high risk of pancreatitis, comparable to that in patients with FCS. Effective, innovative treatments for PC, like apoC-III inhibitors, have been developed. Combined with lifestyle modifications, these agents markedly lower TG levels and risk of pancreatitis in the very-high-risk groups, irrespective of the monogenic etiology. Pragmatic definitions, education, and focus on patients with PC specifically those with alarm features could help mitigate the risk of acute pancreatitis and other complications.

Safety and efficacy of inclisiran in treating hypercholesterolemia: A systemic review and meta-analysis

AIMS

To evaluate the efficacy and safety of inclisiran in the treatment of hypercholesterolemia.

DATE SYNTHESIS

Randomized controlled trials comparing inclisiran with a placebo were searched until April 2024. Overall, 8 studies involving 4947 patients were included. Inclisiran reduced low-density lipoprotein cholesterol (mean difference [MD]: -46.95 %; 95 % confidence interval [CI]: -53.26 to -40.46; P < 0.05), proprotein convertase subtilisin/kexin type 9 (MD: -70.80 %; 95 % CI: -76.52 to -65.08; P < 0.05), serum total cholesterol (MD: -29.47 %; 95 % CI: -32.56 to -26.39; P < 0.05), non-high-density lipoprotein cholesterol (MD: -40.46 %; 95 % CI: -45.24 to -35.68; P < 0.05), apolipoprotein B (MD: -36.77 %; 95 % CI: -40.94 to -32.61; P < 0.05), and lipoprotein(a) (MD: -20.04 %; 95 % CI: -24.2 to -15.87; P < 0.05) levels but increased high-density lipoprotein cholesterol level (MD: 6.09 %; 95 % CI: 3.63 to 8.55; P < 0.05). The incidences of adverse events, serious adverse events, headache, nasopharyngitis, and muscular adverse reactions were not significantly different between the inclisiran and placebo groups. Inclisiran reduced the incidence of cardiovascular adverse reactions (odds ratio [OR] = 0.79; 95 % CI: 0.65 to 0.96; P = 0.02) and increased the incidence of injection-site reactions (OR = 4.79; 95 % CI: 2.18 to 10.52; P < 0.05).

CONCLUSION

Inclisiran is effective in treating hypercholesterolemia and has a good safety profile.

Recognition and management of persistent chylomicronemia: A joint expert clinical consensus by the National Lipid Association and the American Society for Preventive Cardiology

Extreme hypertriglyceridemia, defined as triglyceride (TG) levels ≥1000 mg/dL, is almost always indicative of chylomicronemia. The current diagnostic approach categorizes individuals with chylomicronemia into familial chylomicronemia syndrome (FCS; prevalence 1-10 per million), caused by the biallelic combination of pathogenic variants that impair the lipolytic action of lipoprotein lipase (LPL), or multifactorial chylomicronemia syndrome (MCS, 1 in 500). A pragmatic framework should emphasize the severity of the phenotype and the risk of complications. Therefore, we endorse the term "persistent chylomicronemia (PC)" defined as TG ≥1000 mg/dL in more than half of the measurements to encompass patients with the highest risk for pancreatitis, regardless of their genetic predisposition. We suggest classification of PC into 4 subtypes: (1) genetic FCS, (2) clinical FCS, (3) PC with "alarm" features, and (4) PC without alarm features. Although patients with FCS most likely have PC, the vast majority with PC do not have genetic FCS. Proposed alarm features are: (a) history of recurrent TG-induced acute pancreatitis, (b) recurrent hospitalizations for severe abdominal pain without another identified cause, (c) childhood pancreatitis, (d) family history of TG-induced pancreatitis, and/or (e) postheparin LPL activity <20% of normal value. Alarm features constitute the strongest risk factors for future acute pancreatitis risk. Patients with PC and alarm features have very high risk of pancreatitis, comparable to that in patients with FCS. Effective, innovative treatments for PC, like apolipoprotein C-III inhibitors, have been developed. Combined with lifestyle modifications, these agents markedly lower TG levels and risk of pancreatitis in the very-high-risk groups, irrespective of the monogenic etiology. Pragmatic definitions, education, and focus on patients with PC, specifically those with alarm features, could help mitigate the risk of acute pancreatitis and other complications.

Epidemiology and longitudinal course of chylomicronemia: Insights from NHANES and a large health care system

BACKGROUND

Chylomicronemia is characterized by fasting triglyceride (TG) ≥1000 mg/dL; its longitudinal course is not well studied.

METHODS

Using National Health and Nutrition Examination Survey (NHANES) data (1999-2018; n = 21,998), we determined chylomicronemia prevalence and temporal trend. Using Mayo Clinic data (4,524,506 TG measurements for 1,294,044 individuals), we studied the longitudinal course and ascertained persistent chylomicronemia (PC), defined as TG ≥1000 mg/dL in more than half the measurements for individuals with ≥3 measurements. We used logistic regression to assess factors associated with PC.

RESULTS

In NHANES, the prevalence of chylomicronemia was 0.20% overall, with higher prevalence in men (0.32%) and Hispanics (0.33%). Chylomicronemia prevalence declined from 0.34% in 1999-2004 to 0.11% in 2013-2018, while lipid-lowering pharmacotherapy use in chylomicronemia patients increased from 5.3% to 51.9%. In the Mayo Clinic data, 5618 individuals (0.43%) had at least 1 episode of chylomicronemia. Of these, 8.8% (390 of 4443 with ≥3 measurements) met the operational definition for PC. In individuals with TG <150 mg/dL, 1.3% had a diagnosis of acute pancreatitis, and 0.6% had chronic pancreatitis. Respective figures for individuals with nonpersistent chylomicronemia were 12.5% and 5.1%, and for individuals with PC were 26.2% and 11.5%. Younger age, Hispanic ethnicity, prior pancreatitis, and higher TG levels were associated with PC.

CONCLUSION

In the US, 1 in ∼500 adults has chylomicronemia and 1 in ∼5500 has PC. Individuals with PC have high occurrence of acute and chronic pancreatitis and may need more effective treatment.

Development and Evaluation of a Comprehensive Prediction Model for Incident Coronary Heart Disease Using Genetic, Social, and Lifestyle-Psychological Factors: A Prospective Analysis of the UK Biobank

BACKGROUND

Clinical risk calculators for coronary heart disease (CHD) do not include genetic, social, and lifestyle-psychological risk factors.

OBJECTIVE

To improve CHD risk prediction by developing and evaluating a prediction model that incorporated a polygenic risk score (PRS) and a polysocial score (PSS), the latter including social determinants of health and lifestyle-psychological factors.

DESIGN

Cohort study.

SETTING

United Kingdom.

PARTICIPANTS

UK Biobank participants recruited between 2006 and 2010.

MEASUREMENTS

Incident CHD (myocardial infarction and/or coronary revascularization); 10-year clinical risk based on pooled cohort equations (PCE), Predicting Risk of cardiovascular disease EVENTs (PREVENT), and QRISK3; PRS (Polygenic Score Catalog identification: PGS000018) for CHD (PRSCHD); and PSSCHD from 100 related covariates. Machine-learning and time-to-event analyses and model performance indices.

RESULTS

In 388 224 participants (age, 55.5 [SD, 8.1] years; 42.5% men; 94.9% White), the hazard ratio for 1 SD increase in PSSCHD for incident CHD was 1.43 (95% CI, 1.38 to 1.49; P < 0.001) and for 1 SD increase in PRSCHD was 1.59 (CI, 1.53 to 1.66, P < 0.001). Non-White persons had higher PSSCHD than White persons. The effects of PSSCHD and PRSCHD on CHD were independent and additive. At a 10-year CHD risk threshold of 7.5%, adding PSSCHD and PRSCHD to PCE reclassified 12% of participants, with 1.86 times higher CHD risk in the up- versus down-reclassified persons and showed superior performance compared with PCE as reflected by improved net benefit while maintaining good calibration relative to the clinical risk calculators. Similar results were seen when incorporating PSSCHD and PRSCHD into PREVENT and QRISK3.

LIMITATION

A predominantly White cohort; possible healthy participant effect and ecological fallacy.

CONCLUSION

A PSSCHD was associated with incident CHD and its joint modeling with PRSCHD improved the performance of clinical risk calculators.

PRIMARY FUNDING SOURCE

National Human Genome Research Institute.

Predictors of cardiovascular risk in familial hypercholesterolemia

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Clinical Expression of Familial Hypercholesterolemia in Patients from France and French Canada Carrying Identical-by-Descent Pathogenic LDLR Gene Variants: A Proof-of-Concept Study

Background: Studying patients carrying identical-by-descent (IBD) pathogenic gene variants allows us to control for the disease-causing genetic background and to more accurately document the impact of modifiers. Familial hypercholesterolemia (FH) is characterized by elevated low-density lipoprotein cholesterol (LDL-c) levels and premature atherosclerosis and is often caused by defects in the LDLR gene. There is a high prevalence of FH in French Canada as a result of a founder effect from France in the 17th century. Several FH patients currently living in French Canada (founder population) and in France (colonizing population) carry IBD FH-causing variants. The expression of FH is affected by environmental and genetic modifiers, and patients with IBD variants may present different characteristics. Methods: In this study, we compared FH clinical expression patients carrying IBD LDLR pathogenic variants living in France or Canada. Four IBD variants, namely c.259T>G p.(Trp87Gly), c.2000G>A p.(Cys667Tyr), c.682G>A p.(Glu228Lys), and c.1048C>T p.(Arg350*), were selected. Untreated plasma lipid profiles, the apolipoprotein E (APOE) genotype, cardiovascular risk factors, and the occurrence of symptomatic ASCVD were compared in 105 adult carriers (30 from France and 75 from French Canada). Results: All parameters were similar between the two populations, except for untreated total cholesterol (10.14 ± 1.89 mmol/L vs. 8.65 ± 1.84 mmol/L, p = 0.0006) and LDL-c concentrations (7.94 ± 1.86 mmol/L vs. 6.93 ± 1.78 mmol/L, p = 0.016), which were significantly higher in FH patients living in France, an observation that was revealed across all studied LDLR variants. Conclusions: This study illustrates that FH patients sharing IBD pathogenic LDLR variants that have evolved in different geographic, cultural, and socio-economic environments for hundreds of years differ in terms of cholesterol levels, highlighting the importance of better understanding the interplay between genetic and environmental modulators of FH expression.

The Efficacy of Tafolecimab in Chinese Patients with Hypercholesterolemia: A Systematic Review and Meta-analysis

BACKGROUND

Cardiovascular disease was the leading cause of death worldwide in 2021, with atherosclerotic cardiovascular disease, encompassing hypercholesterolemia, being a major contributing factor. A range of lipid-lowering medications is used for the management of hyperlipidemia, but the use of statins is considered as standard therapy. Unfortunately, some patients do not respond to this therapy, necessitating novel therapeutic approaches. Tafolecimab is a novel proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibody that inhibits the binding of PCSK9 with low-density lipoprotein receptors (LDLRs) and increases LDLR recycling, and thus it indirectly lowers circulating low-density lipoprotein cholesterol (LDL-C) levels by increasing LDL-C uptake. The primary objective of this study is to assess the efficacy of tafolecimab in reducing LDL-C levels.

METHODS

A thorough search was conducted on Medline (PubMed), Cochrane CENTRAL, Scopus, and Google Scholar from inception until December 2023. Review Manager was used for statistical analysis. The random effects model was used to calculate risk ratios (RRs), mean differences (MDs), and 95% confidence intervals (CIs). Heterogeneity was assessed using the Higgins I2 index. The risk of bias was assessed using Cochrane's RoB 2 tool. This review has been registered with PROSPERO (CRD42023471020).

RESULTS

A total of four Chinese studies matched the inclusion criteria and were included in this review. A total of 726 patients were included in this review, out of which 476 patients were males. Out of four, three studies that studied the efficacy of 450 mg tafolecimab every 4 weeks in patients (n = 462) as compared to placebo (n = 224) were included in the meta-analysis. According to the pooled results, tafolecimab caused a significant decrease in LDL-C levels from baseline to week 12 as compared to placebo (MD = - 63.78, 95% CI - 65.88 to - 61.68, p value < 0.00001, I2 = 97%). The pooled results showed that more patients achieved ≥ 50% reductions in LDL-C levels (RR = 52.33, 95% CI 18.51-147.95, p value < 0.00001, I2 = 0%) and LDL-C < 1.8 mmol/L (RR = 17.27, 95% CI 9.59-31.11, p value < 0.00001, I2 = 0%) at week 12 in the tafolecimab group than the placebo group. Additionally, tafolecimab also caused a robust decrease in non-HDL-C, apolipoprotein B, and lipoprotein(a) levels from baseline to week 12 compared to placebo. The overall risk of bias was low, as determined by the RoB 2 tool.

CONCLUSIONS

Tafolecimab showed promising lipid-lowering efficacy and a well-tolerated safety profile. Our findings suggest its potential as an innovative therapeutic option for individuals with hypercholesterolemia; however, significant heterogeneity was observed in some results, making it difficult to come to a firm conclusion. Therefore, large-scale randomized trials are required to confirm our findings, particularly exploring the most effective dosage regimens across varied populations.

REGISTRATION

PROSPERO identifier number CRD42023471020.

Using implementation science to evaluate a population-wide genomic screening program: Findings from the first 20,000 In Our DNA SC participants

We use the implementation science framework RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) to describe outcomes of In Our DNA SC, a population-wide genomic screening (PWGS) program. In Our DNA SC involves participation through clinical appointments, community events, or at home collection. Participants provide a saliva sample that is sequenced by Helix, and those with a pathogenic variant or likely pathogenic variant for CDC Tier 1 conditions are offered free genetic counseling. We assessed key outcomes among the first cohort of individuals recruited. Over 14 months, 20,478 participants enrolled, and 14,053 samples were collected. The majority selected at-home sample collection followed by clinical sample collection and collection at community events. Participants were predominately female, White (self-identified), non-Hispanic, and between the ages of 40-49. Participants enrolled through community events were the most racially diverse and the youngest. Half of those enrolled completed the program. We identified 137 individuals with pathogenic or likely pathogenic variants for CDC Tier 1 conditions. The majority (77.4%) agreed to genetic counseling, and of those that agreed, 80.2% completed counseling. Twelve clinics participated, and we conducted 108 collection events. Participants enrolled at home were most likely to return their sample for sequencing. Through this evaluation, we identified facilitators and barriers to implementation of our state-wide PWGS program. Standardized reporting using implementation science frameworks can help generalize strategies and improve the impact of PWGS.

Predictors of cardiovascular risk in familial hypercholesterolemia

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Novel Finnish-enriched variants causing severe hypercholesterolemia and their clinical impact on coronary artery disease

BACKGROUND AND AIMS

Severe hypercholesterolemia (LDL-cholesterol ≥ 5 mmol/l) is a major risk factor for coronary artery disease (CAD). The etiology incudes both genetic and nongenetic factors, but persons carrying mutations in known hypercholesterolemia-associated genes are at significantly higher CAD risk than non-carriers. Yet, a significant proportion of mutation carriers remains undetected while the assessment of genetic candidate variants in clinical practice is challenging.

METHODS

To address these challenges, we set out to test the utility of a practical approach to leverage data from a large reference cohort, the FinnGen Study encompassing 356,082 persons with extensive longitudinal health record information, to aid the clinical evaluation of single genetic candidate genes variants detected by exome sequence analysis in a target population of 351 persons with severe hypercholesterolemia.

RESULTS

We identified 23 rare missense mutations in known hypercholesterolemia genes, 3 of which were previously described mutations (LDLR Pro309Lysfs, LDLR Arg595Gln and APOB Arg3527Gln). Subsequent in silico and clinical assessment of the remaining 20 variants pinpointed two likely hypercholesterolemia-associated variants in LDLR (Arg574Leu and Glu626Lys) and one in LDLRAP1 (Arg151Trp). Heterozygous carriers of the novel LDLR and LDLRAP1 variants received statin treatment more often than non-carriers (OR 2.1, p = 1.8e-6 and OR 1.4, p = 0.001) and untreated carriers had higher risk for ischemic heart disease (OR 2.0, p = 0.03 and OR 1.8, p = 0.008).

CONCLUSIONS

Our data elucidate the wide spectrum of genetic variants impacting hypercholesterolemia and demonstrate the utility of a large reference population to assess the heterogeneous impact of candidate gene variants on cardiovascular disease risk.

Deep generative models of LDLR protein structure to predict variant pathogenicity

The complex structure and function of low density lipoprotein receptor (LDLR) makes classification of protein-coding missense variants challenging. Deep generative models, including Evolutionary model of Variant Effect (EVE), Evolutionary Scale Modeling (ESM), and AlphaFold 2 (AF2), have enabled significant progress in the prediction of protein structure and function. ESM and EVE directly estimate the likelihood of a variant sequence but are purely data-driven and challenging to interpret. AF2 predicts LDLR structures, but variant effects are explicitly modeled by estimating changes in stability. We tested the effectiveness of these models for predicting variant pathogenicity compared to established methods. AF2 produced two distinct conformations based on a novel hinge mechanism. Within ESM's hidden space, benign and pathogenic variants had different distributions. In EVE, these distributions were similar. EVE and ESM were comparable to Polyphen-2, SIFT, REVEL, and Primate AI for predicting binary classifications in ClinVar. However, they were more strongly correlated with experimental measures of LDL uptake. AF2 poorly performed in these tasks. Using the UK Biobank to compare association with clinical phenotypes, ESM and EVE were more strongly associated with serum LDL-C than Polyphen-2. ESM was able to identify variants with more extreme LDL-C levels than EVE and had a significantly stronger association with atherosclerotic cardiovascular disease. In conclusion, AF2 predicted LDLR structures do not accurately model variant pathogenicity. ESM and EVE are competitive with prior scoring methods for prediction based on binary classifications in ClinVar but are superior based on correlations with experimental assays and clinical phenotypes.

Use of a multi-phased approach to identify and address facilitators and barriers to the implementation of a population-wide genomic screening program

INTRODUCTION

Population-wide genomic screening for CDC Tier-1 conditions offers the ability to identify the 1-2% of the US population at increased risk for Hereditary Breast and Ovarian Cancer, Lynch Syndrome, and Familial Hypercholesterolemia. Implementation of population-wide screening programs is highly complex, requiring engagement of diverse collaborators and implementation teams. Implementation science offers tools to promote integration of these programs through the identification of determinants of success and strategies to address potential barriers.

METHODS

Prior to launching the program, we conducted a pre-implementation survey to assess anticipated barriers and facilitators to reach, effectiveness, adoption, implementation, and maintenance (RE-AIM), among 51 work group members (phase 1). During the first year of program implementation, we completed coding of 40 work group meetings guided by the Consolidated Framework for Implementation Research (CFIR) (phase 2). We matched the top barriers to implementation strategies identified during phase 2 using the CFIR-ERIC (Expert Recommendation for Implementing Change) matching tool.

RESULTS

Staffing and workload concerns were listed as the top barrier in the pre-implementation phase of the program. Top barriers during implementation included adaptability (n = 8, 20%), complexity (n = 14, 35%), patient needs and resources (n = 9, 22.5%), compatibility (n = 11, 27.5%), and self-efficacy (n = 9, 22.5%). We identified 16 potential implementation strategies across six ERIC clusters to address these barriers and operationalized these strategies for our specific setting and program needs.

CONCLUSION

Our findings provide an example of successful use of the CFIR-ERIC tool to guide implementation of a population-wide genomic screening program.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Polygenic Risk, Rare Variants, and Family History: Independent and Additive Effects on Coronary Heart Disease

Background

Genetic factors are not included in prediction models for coronary heart disease (CHD).

Objectives

The authors assessed the predictive utility of a polygenic risk score (PRS) for CHD (defined as myocardial infarction, coronary revascularization, or cardiovascular death) and whether the risks due to monogenic familial hypercholesterolemia (FH) and family history (FamHx) are independent of and additive to the PRS.

Methods

In UK-biobank participants, PRSCHD was calculated using metaGRS, and 10-year risk for incident CHD was estimated using the pooled cohort equations (PCE). The area under the curve (AUC) of the receiver operator curve and net reclassification improvement (NRI) were assessed. FH was defined as the presence of a pathogenic or likely pathogenic variant in LDLR, APOB, or PCSK9. FamHx was defined as a diagnosis of CHD in first-degree relatives. Independent and additive effects of PRSCHD, FH, and FamHx were evaluated in stratified analyses.

Results

In 323,373 participants with genotype data, the addition of PRSCHD to PCE increased the AUC from 0.759 (95% CI: 0.755-0.763) to 0.773 (95% CI: 0.769-0.777). The AUC and NRIEvent for PRSCHD were higher before the age of 55 years. Of 199,997 participants with exome sequence data, 10,000 had a PRSCHD ≥95th percentile (PRSP95), 673 had FH, and 46,163 had FamHx. The CHD risk associated with PRSP95 was independent of FH and FamHx. The risks associated with combinations of PRSCHD, FH, and FamHx were additive and comprehensive estimates could be obtained by multiplying the risk from each genetic factor.

Conclusions

Incorporating PRSCHD into the PCE improves risk prediction for CHD, especially at younger ages. The associations of PRSCHD, FH, and FamHx with CHD were independent and additive.

Barriers and shortcomings in access to cardiovascular management and prevention for familial hypercholesterolemia during the COVID-19 pandemic

Familial hypercholesterolemia (FH) is a hereditary condition caused by mutations in the lipid pathway. The goal in managing FH is to reduce circulating low-density lipoprotein cholesterol and, therefore, reduce the risk of developing atherosclerotic cardiovascular disease (ASCVD). Because FH patients were considered high risk groups due to an increased susceptible for contracting COVID-19 infection, we hypothesized whether the effects of the pandemic hindered access to cardiovascular care. In this review, we conducted a literature search in databases Pubmed/Medline and ScienceDirect. We included a comprehensive analysis of findings from articles in English related and summarized the effects of the pandemic on cardiovascular care through direct and indirect effects. During the COVID-19 pandemic, FH patients presented with worse outcomes and prognosis, especially those that have suffered from early ASCVD. This caused avoidance in seeking care due to fear of transmission. The pandemic severely impacted consultations with lipidologists and cardiologists, causing a decline in lipid profile evaluations. Low socioeconomic communities and ethnic minorities were hit the hardest with job displacements and lacked healthcare coverage respectively, leading to treatment nonadherence. Lock-down restrictions promoted sedentary lifestyles and intake of fatty meals, but it is unclear whether these factors attenuated cardiovascular risk in FH. To prevent early atherogenesis in FH patients, universal screening programs, telemedicine, and lifestyle interventions are important recommendations that could improve outcomes in FH patients. However, the need to research in depth on the disproportionate impact within different subgroups should be the forefront of FH research.

Identification of pathogenic variants in the Brazilian cohort with Familial Hypercholesterolemia using exon-targeted gene sequencing

Familial hypercholesterolemia (FH) is a monogenic disease characterized by high plasma low-density lipoprotein cholesterol (LDL-c) levels and increased risk of premature atherosclerotic cardiovascular disease. Mutations in FH-related genes account for 40% of FH cases worldwide. In this study, we aimed to assess the pathogenic variants in FH-related genes in the Brazilian FH cohort FHBGEP using exon-targeted gene sequencing (ETGS) strategy. FH patients (n=210) were enrolled at five clinical sites and peripheral blood samples were obtained for laboratory testing and genomic DNA extraction. ETGS was performed using MiSeq platform (Illumina). To identify deleterious variants in LDLR, APOB, PCSK9, and LDLRAP1, the long-reads were subjected to Burrows-Wheeler Aligner (BWA) for alignment and mapping, followed by variant calling using Genome Analysis Toolkit (GATK) and ANNOVAR for variant annotation. The variants were further filtered using in-house custom scripts and classified according to the American College Medical Genetics and Genomics (ACMG) guidelines. A total of 174 variants were identified including 85 missense, 3 stop-gain, 9 splice-site, 6 InDel, and 71 in regulatory regions (3'UTR and 5'UTR). Fifty-two patients (24.7%) had 30 known pathogenic or likely pathogenic variants in FH-related genes according to the American College Medical and Genetics and Genomics guidelines. Fifty-three known variants were classified as benign, or likely benign and 87 known variants have shown uncertain significance. Four novel variants were discovered and classified as such due to their absence in existing databases. In conclusion, ETGS and in silico prediction studies are useful tools for screening deleterious variants and identification of novel variants in FH-related genes, they also contribute to the molecular diagnosis in the FHBGEP cohort.

The burden of severe hypercholesterolemia and familial hypercholesterolemia in a population-based setting in the US

Background

Contemporary prevalence, awareness, and control of severe hypercholesterolemia (SH) and familial hypercholesterolemia (FH) and the associated atherosclerotic cardiovascular disease risk in the US are unknown.

Method

Using electronic health records, we assessed the burden of SH and FH in Olmsted County, Minnesota, US, between 2004 and 2015. We defined SH as low-density lipoprotein cholesterol (LDL-C) level ≥190 mg/dl without secondary causes of hypercholesterolemia and FH as a Dutch Lipid Clinic Network score ≥6. Controls were age- and sex-matched individuals with LDL-C level <190 mg/dl.

Results

The age- and sex-adjusted point and period prevalence (age-recursive method) of SH was 4.44% and 8.95%, respectively; 1 in 21 had FH (∼1:233 adults), and 46.2% had a recorded diagnosis. Guideline recommended targets (LDL-C <100 mg/dl and <70 mg/dl in the primary and secondary prevention settings, respectively) were achieved in 33.1% and 21.2% of SH cases, with less women overall achieving the target than men (18.6% vs. 23.7%, p=0.022). After adjustment for conventional risk factors, the hazard ratio for incident coronary heart disease (CHD) in those with SH was 1.21 (1.05-1.39; p=0.010), in those with SH and a family history of CHD was 2.16 (1.57-2.96; p<0.001) and in those with FH was 4.61 (2.66-7.97; p<0.001). The association of SH with CHD was modified by age (p-interaction = 0.015), such that the risk was greater at younger ages.

Conclusions

SH was prevalent and an independent risk factor for incident CHD. Awareness and control were low, highlighting a treatment gap (more prominent in women) that needs to be addressed.

The Inherited Hypercholesterolemias

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

The Prevalence and Genetic Spectrum of Familial Hypercholesterolemia in Qatar Based on Whole Genome Sequencing of 14,000 Subjects

Familial hypercholesterolemia (FH) is an inherited disease characterized by reduced efficiency of low-density lipoprotein-cholesterol (LDL-C) removal from the blood and, consequently, an increased risk of life-threatening early cardiovascular complications. In Qatar, the prevalence of FH has not been determined and the disease, as in many countries, is largely underdiagnosed. In this study, we combined whole-genome sequencing data from the Qatar Genome Program with deep phenotype data from Qatar Biobank for 14,056 subjects to determine the genetic spectrum and estimate the prevalence of FH in Qatar. We used the Dutch Lipid Clinic Network (DLCN) as a diagnostic tool and scrutinized 11 FH-related genes for known pathogenic and possibly pathogenic mutations. Results revealed an estimated prevalence of 0.8% (1:125) for definite/probable cases of FH in the Qatari population. We detected 16 known pathogenic/likely pathogenic mutations in LDLR and one in PCSK9; all in a heterozygous state with high penetrance. The most common mutation was rs1064793799 (c.313+3A >C) followed by rs771019366 (p.Asp90Gly); both in LDLR. In addition, we identified 18 highly penetrant possibly pathogenic variants, of which 5 were Qatari-specific, in LDLR, APOB, PCSK9 and APOE, which are predicted to be among the top 1% most deleterious mutations in the human genome but further validations are required to confirm their pathogenicity. We did not detect any homozygous FH or autosomal recessive mutations in our study cohort. This pioneering study provides a reliable estimate of FH prevalence in Qatar based on a significantly large population-based cohort, whilst uncovering the spectrum of genetic variants associated with FH.

Lipid Metabolic Genes and Maternal Supraphysiological Hypercholesterolemia: An Analysis of Maternal-fetal Interaction

CONTEXT

The joint associations of maternal and fetal single nucleotide polymorphisms (SNPs) of lipid metabolic genes with the risk of maternal supraphysiological hypercholesterolemia (MSPH) are unclear.

OBJECTIVE

This study aims to investigate the associations of maternal/fetal SNPs of APOE, LPL, LDLR, PCSK9, and SCARB1 with the risk of MSPH and explore whether the maternal-fetal pairing pattern of the risk alleles can affect MSPH risk.

METHODS

A nested case-control study was conducted that included 182 pregnant women with MSPH and 182 with maternal physiological hypercholesterolemia. Maternal venous and umbilical venous blood were collected to detect the SNPs of genes. The primary outcome was MSPH. Logistic regression model was used to determine the associations of SNPs with risk of MSPH.

RESULTS

The C-allele in maternal APOE rs429358 T > C (adjusted odds ratio [OR] = 1.72, P = 0.033), G-allele in fetal APOE rs440446 C > G (adjusted OR = 1.62, P = 0.012) and T-allele in fetal LPL rs263 C > T (adjusted OR = 1.53, P = 0.011) increased the risk of MSPH. The A-allele in maternal LDLR rs7258950 G > A decreased the risk of MSPH (adjusted OR = 0.67, P = 0.028). For maternal-fetal pairing analysis, the variant concordance of PCSK9 rs2149041, rs7523141, rs7523242, rs7525649, and LDLR rs7258950 were associated with the decreased risk of MSPH under the dominant model. The variant concordance of other SNPs of PCSK9, APOE, LDLR, LPL, and SCARB1 were associated with the increased risk of MSPH.

CONCLUSION

This study supports the hypothesis that maternal and fetal genetic polymorphisms of lipid metabolic genes are associated with the risk of MSPH. The maternal-fetal variant concordance is also associated with this risk.

A pragmatic implementation research study for In Our DNA SC: a protocol to identify multi-level factors that support the implementation of a population-wide genomic screening initiative in diverse populations

BACKGROUND

In 2021, the Medical University of South Carolina (MUSC) partnered with Helix, a population genetic testing company, to offer population-wide genomic screening for Centers for Disease Control and Preventions' Tier 1 conditions of hereditary breast and ovarian cancer, Lynch syndrome, and familial hypercholesterolemia to 100,000 individuals in South Carolina. We developed an implementation science protocol to study the multi-level factors that influence the successful implementation of the In Our DNA SC initiative.

METHODS

We will use a convergent parallel mixed-methods study design to evaluate the implementation of planned strategies and associated outcomes for In Our DNA SC. Aims focus on monitoring participation to ensure engagement of diverse populations, assessing contextual factors that influence implementation in community and clinical settings, describing the implementation team's facilitators and barriers, and tracking program adaptations. We report details about each data collection tool and analyses planned, including surveys, interview guides, and tracking logs to capture and code work group meetings, adaptations, and technical assistance needs.

DISCUSSION

The goal of In Our DNA SC is to provide population-level screening for actionable genetic conditions and to foster ongoing translational research. The use of implementation science can help better understand how to support the success of In Our DNA SC, identify barriers and facilitators to program implementation, and can ensure the sustainability of population-level genetic testing. The model-based components of our implementation science protocol can support the identification of best practices to streamline the expansion of similar population genomics programs at other institutions.

LDL-C Concentrations and the 12-SNP LDL-C Score for Polygenic Hypercholesterolaemia in Self-Reported South Asian, Black and Caribbean Participants of the UK Biobank

Background: Monogenic familial hypercholesterolaemia (FH) is an autosomal dominant disorder characterised by elevated low-density lipoprotein cholesterol (LDL-C) concentrations due to monogenic mutations in LDLR, APOB, PCSK9, and APOE. Some mutation-negative patients have a polygenic cause for elevated LDL-C due to a burden of common LDL-C-raising alleles, as demonstrated in people of White British (WB) ancestry using a 12-single nucleotide polymorphism (SNP) score. This score has yet to be evaluated in people of South Asian (SA), and Black and Caribbean (BC) ethnicities. Objectives: 1) Compare the LDL-C and 12-SNP score distributions across the three major ethnic groups in the United Kingdom: WB, SA, and BC individuals; 2) compare the association of the 12-SNP score with LDL-C in these groups; 3) evaluate ethnicity-specific and WB 12-SNP score decile cut-off values, applied to SA and BC ethnicities, in predicting LDL-C concentrations and hypercholesterolaemia (LDL-C>4.9 mmol/L). Methods: The United Kingdom Biobank cohort was used to analyse the LDL-C (adjusted for statin use) and 12-SNP score distributions in self-reported WB (n = 353,166), SA (n = 7,016), and BC (n = 7,082) participants. To evaluate WB and ethnicity-specific 12-SNP score deciles, the total dataset was split 50:50 into a training and testing dataset. Regression analyses (logistic and linear) were used to analyse hypercholesterolaemia (LDL-C>4.9 mmol/L) and LDL-C. Findings: The mean (±SD) measured LDL-C differed significantly between the ethnic groups and was highest in WB [3.73 (±0.85) mmol/L], followed by SA [3.57 (±0.86) mmol/L, p < 2.2 × 10^-16], and BC [3.42 (±0.90) mmol/L] participants (p < 2.2 × 10^-16). There were significant differences in the mean (±SD) 12-SNP score between WB [0.90 (±0.23)] and BC [0.72 (±0.25), p < 2.2 × 10^-16], and WB and SA participants [0.86 (±0.19), p < 2.2 × 10^-16]. In all three ethnic groups the 12-SNP score was associated with measured LDL-C [R ² (95% CI): WB = 0.067 (0.065-0.069), BC = 0.080 (0.063-0.097), SA = 0.027 (0.016-0.038)]. The odds ratio and the area under the curve for hypercholesterolaemia were not statistically different when applying ethnicity-specific or WB deciles in all ethnic groups. Interpretation: We provide information on the differences in LDL-C and the 12-SNP score distributions in self-reported WB, SA, and BC individuals of the United Kingdom Biobank. We report the association between the 12-SNP score and LDL-C in these ethnic groups. We evaluate the performance of ethnicity-specific and WB 12-SNP score deciles in predicting LDL-C and hypercholesterolaemia.

Polygenic contribution for familial hypercholesterolemia (FH)

PURPOSE OF REVIEW

The present review summarizes different polygenic risk scores associated with hypercholesterolemia applied to cohorts with a genetic diagnosis of familial hypercholesterolemia (FH).

RECENT FINDINGS

Several single-nucleotide polymorphisms associated with increased levels of LDL-C or Lp(a) have been genotyped in population cohorts with FH phenotype, to identify the cause of hypercholesterolemia in mutation negative individuals. In different studies, a large proportion of individuals without a monogenic causative variant (in low density lipoprotein receptor gene (LDLR), apolipoprotein B gene (APOB) or proprotein convertase subtilisin/kexin type 9 gene (PCSK9 genes) was considered to have a hypercholesterolemia with a polygenic basis. The heterogeneity in the phenotype of monogenic FH may also be explained by polygenic contributions to LDL-C. The elevated LDL-C genetic risk score (GRS) has been associated with increased risk of atherosclerotic cardiovascular disease in individuals with monogenic FH. Moreover, a poorer response to lipid lowering therapy has been associated with monogenic FH when compared to a polygenic basis. The reason why Lp(a) concentrations are raised in individuals with clinical FH is unclear, but it could be caused by a genetic variation in Lipoprotein(A) gene as a polygenic contribution.

SUMMARY

Polygenic risk scores have revealed to be important tools to define the cause of hypercholesterolemia in FH mutation-negative individuals and should be included in FH diagnosis strategies, although there is still space for more specific LDL-C GRS to be developed. The use of GRS may be used to refine cardiovascular risk prediction in FH patients and could lead to a personalized approach to therapy. The identification of the genetic status of an individual with FH phenotype (monogenic or polygenic) may have implications on their risk stratification, cascade screening of relatives, disease management and therapeutic measures.

Genetics and prescription opioid use (GaPO): study design for consenting a cohort from an existing biobank to identify clinical and genetic factors influencing prescription opioid use and abuse

BACKGROUND

Prescription opioids (POs) are commonly used to treat moderate to severe chronic pain in the health system setting. Although they improve quality of life for many patients, more work is needed to identify both the clinical and genetic factors that put certain individuals at high risk for developing opioid use disorder (OUD) following use of POs for pain relief. With a greater understanding of important risk factors, physicians will be better able to identify patients at highest risk for developing OUD for whom non-opioid alternative therapies and treatments should be considered.

METHODS

We are conducting a prospective observational study that aims to identify the clinical and genetic factors most stongly associated with OUD. The study design leverages an existing biobank that includes whole exome sequencing and array genotyping. The biobank is maintained within an integrated health system, allowing for the large-scale capture and integration of genetic and non-genetic data. Participants are enrolled into the health system biobank via informed consent and then into a second study that focuses on opioid medication use. Data capture includes validated self-report surveys measuring addiction severity, depression, anxiety, and nicotine use, as well as additional clinical, prescription, and brain imaging data extracted from electronic health records.

DISCUSSION

We will harness this multimodal data capture to establish meaningful patient phenotypes in order to understand the genetic and non-genetic contributions to OUD.