Polygenic Background Modifies Risk of Coronary Artery Disease Among Individuals With Heterozygous Familial Hypercholesterolemia

On Penetrance Estimation in Family, Clinical, and Population Cohorts

In recent years, there has been a considerable influx of publications assessing the penetrance of pathogenic variants associated with monogenic diseases with dominant inheritance. As large and diverse groups have been sequenced, it has become clear that incomplete penetrance is common to most hereditary diseases, as numerous molecular, genetic, or environmental factors can cause clinical diversity among the carriers of the same variant. In this review, we discuss some of these factors and focus on the existing approaches to estimating penetrance, depending on the data available and their application to different data sets. We also list some currently available large-scale data sets with penetrance estimates.

Polygenic risk score for coronary artery disease predicts atherosclerotic cardiovascular disease in familial hypercholesterolemia

BACKGROUND

Patients with familial hypercholesterolemia (FH) are at increased risk of atherosclerotic cardiovascular disease (ASCVD). However, this risk is heterogeneous, and the contribution of several clinical risk factors has been well demonstrated in this population. The proportion of the risk conferred by the accumulation of common small effect variants in coronary artery disease (CAD) susceptibility genes remains to be determined.

OBJECTIVE

The objective was to determine if a weighted polygenic risk score (PRS) for CAD (PRSCAD) is associated with ASCVD risk in patients with heterozygous FH (HeFH).

METHODS

This study included 1886 participants with HeFH from 3 independent cohorts: the FH Canada national registry, the UK Biobank, and the Montreal Clinical Research Institute FH cohort. The lifelong ASCVD risk was compared between groups using Kaplan-Meier estimates and Cox proportional hazards regression models.

RESULTS

The group with a high PRSCAD (>75th percentile) had a ∼2-fold increased risk of ASCVD compared to those with a lower PRSCAD (≤75th percentile) (HR 1.92 (1.55-2.37), P < .0001). The effect of the PRSCAD on ASCVD risk remained significant after correction for clinical risk factors (P = .0002). This association was similar between women and men (P interaction = .68), between genetic and clinical FH (P interaction = .48), between cohorts (P interaction = .39), and between the type of PRS (P interaction = .81).

CONCLUSION

We demonstrated in the largest study to date that the use of a PRSCAD allowed us to further refine risk stratification in HeFH. Further studies are needed to evaluate the clinical value of adding the PRSCAD to current risk prediction tools.

Polygenic Risk Is Associated With Long-Term Coronary Plaque Progression and High-Risk Plaque

BACKGROUND

The longitudinal relation between coronary artery disease (CAD) polygenic risk score (PRS) and long-term plaque progression and high-risk plaque (HRP) features is unknown.

OBJECTIVES

The goal of this study was to investigate the impact of CAD PRS on long-term coronary plaque progression and HRP.

METHODS

Patients underwent CAD PRS measurement and prospective serial coronary computed tomography angiography (CTA) imaging. Coronary CTA scans were analyzed with a previously validated artificial intelligence-based algorithm (atherosclerosis imaging-quantitative computed tomography imaging). The relationship between CAD PRS and change in percent atheroma volume (PAV), percent noncalcified plaque progression, and HRP prevalence was investigated in linear mixed-effect models adjusted for baseline plaque volume and conventional risk factors.

RESULTS

A total of 288 subjects (mean age 58 ± 7 years; 60% male) were included in this study with a median scan interval of 10.2 years. At baseline, patients with a high CAD PRS had a more than 5-fold higher PAV than those with a low CAD PRS (10.4% vs 1.9%; P < 0.001). Per 10 years of follow-up, a 1 SD increase in CAD PRS was associated with a 0.69% increase in PAV progression in the multivariable adjusted model. CAD PRS provided additional discriminatory benefit for above-median noncalcified plaque progression during follow-up when added to a model with conventional risk factors (AUC: 0.73 vs 0.69; P = 0.039). Patients with high CAD PRS had an OR of 2.85 (95% CI: 1.14-7.14; P = 0.026) and 6.16 (95% CI: 2.55-14.91; P < 0.001) for having HRP at baseline and follow-up compared with those with low CAD PRS.

CONCLUSIONS

Polygenic risk is strongly associated with future long-term plaque progression and HRP in patients suspected of having CAD.

Influence of Polygenic Background on the Clinical Presentation of Familial Hypercholesterolemia

BACKGROUND

Heterozygous familial hypercholesterolemia (FH) is among the most common genetic conditions worldwide that affects ≈ 1 in 300 individuals. FH is characterized by increased levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of coronary artery disease (CAD), but there is a wide spectrum of severity within the FH population. This variability in expression is incompletely explained by known risk factors. We hypothesized that genome-wide genetic influences, as represented by polygenic risk scores (PRSs) for cardiometabolic traits, would influence the phenotypic severity of FH.

METHODS

We studied individuals with clinically diagnosed FH (n=1123) from the FH Canada National Registry, as well as individuals with genetically identified FH from the UK Biobank (n=723). For all individuals, we used genome-wide gene array data to calculate PRSs for CAD, LDL-C, lipoprotein(a), and other cardiometabolic traits. We compared the distribution of PRSs in individuals with clinically diagnosed FH, genetically diagnosed FH, and non-FH controls and examined the association of the PRSs with the risk of atherosclerotic cardiovascular disease.

RESULTS

Individuals with clinically diagnosed FH had higher levels of LDL-C, and the incidence of atherosclerotic cardiovascular disease was higher in individuals with clinically diagnosed compared with genetically identified FH. Individuals with clinically diagnosed FH displayed enrichment for higher PRSs for CAD, LDL-C, and lipoprotein(a) but not for other cardiometabolic risk factors. The CAD PRS was associated with a risk of atherosclerotic cardiovascular disease among individuals with an FH-causing genetic variant.

CONCLUSIONS

Genetic background, as expressed by genome-wide PRSs for CAD, LDL-C, and lipoprotein(a), influences the phenotypic severity of FH, expanding our understanding of the determinants that contribute to the variable expressivity of FH. A PRS for CAD may aid in risk prediction among individuals with FH.