Pathogenic TSR1 Gene Variants in Patients With Spontaneous Coronary Artery Dissection

A Multi-Ancestry Polygenic Risk Score for Coronary Heart Disease Based on an Ancestrally Diverse Genome-Wide Association Study and Population-Specific Optimization

Background

Predictive performance of polygenic risk scores (PRS) varies across populations. To facilitate equitable clinical use, we developed PRS for coronary heart disease (PRSCHD) for 5 genetic ancestry groups.

Methods

We derived ancestry-specific and multi-ancestry PRSCHD based on pruning and thresholding (PRSP+T) and continuous shrinkage priors (PRSCSx) applied on summary statistics from the largest multi-ancestry genome-wide meta-analysis for CHD to date, including 1.1 million participants from 5 continental populations. Following training and optimization of PRSCHD in the Million Veteran Program, we evaluated predictive performance of the best performing PRSCHD in 176,988 individuals across 9 cohorts of diverse genetic ancestry.

Results

Multi-ancestry PRSP+T outperformed ancestry specific PRSP+T across a range of tuning values. In training stage, for all ancestry groups, PRSCSx performed better than PRSP+T and multi-ancestry PRS outperformed ancestry-specific PRS. In independent validation cohorts, the selected multi-ancestry PRSP+T demonstrated the strongest association with CHD in individuals of South Asian (SAS) and European (EUR) ancestry (OR per 1SD[95% CI]; 2.75[2.41-3.14], 1.65[1.59-1.72]), followed by East Asian (EAS) (1.56[1.50-1.61]), Hispanic/Latino (HIS) (1.38[1.24-1.54]), and weakest in African (AFR) ancestry (1.16[1.11-1.21]). The selected multi-ancestry PRSCSx showed stronger associacion with CHD in comparison within each ancestry group where the association was strongest in SAS (2.67[2.38-3.00]) and EUR (1.65[1.59-1.71]), progressively decreasing in EAS (1.59[1.54-1.64]), HIS (1.51[1.35-1.69]), and lowest in AFR (1.20[1.15-1.26]).

Conclusions

Utilizing diverse summary statistics from a large multi-ancestry genome-wide meta-analysis led to improved performance of PRSCHD in most ancestry groups compared to single-ancestry methods. Improvement of predictive performance was limited, specifically in AFR and HIS, despite use of one of the largest and most diverse set of training and validation cohorts to date. This highlights the need for larger GWAS datasets of AFR and HIS individuals to enhance performance of PRSCHD.

Arterial dissections: Common features and new perspectives

Arterial dissections, which involve an abrupt tear in the wall of a major artery resulting in the intramural accumulation of blood, are a family of catastrophic disorders causing major, potentially fatal sequelae. Involving diverse vascular beds, including the aorta or coronary, cervical, pulmonary, and visceral arteries, each type of dissection is devastating in its own way. Traditionally they have been studied in isolation, rather than collectively, owing largely to the distinct clinical consequences of dissections in different anatomical locations - such as stroke, myocardial infarction, and renal failure. Here, we review the shared and unique features of these arteriopathies to provide a better understanding of this family of disorders. Arterial dissections occur commonly in the young to middle-aged, and often in conjunction with hypertension and/or migraine; the latter suggesting they are part of a generalized vasculopathy. Genetic studies as well as cellular and molecular investigations of arterial dissections reveal striking similarities between dissection types, particularly their pathophysiology, which includes the presence or absence of an intimal tear and vasa vasorum dysfunction as a cause of intramural hemorrhage. Pathway perturbations common to all types of dissections include disruption of TGF-β signaling, the extracellular matrix, the cytoskeleton or metabolism, as evidenced by the finding of mutations in critical genes regulating these processes, including LRP1, collagen genes, fibrillin and TGF-β receptors, or their coupled pathways. Perturbances in these connected signaling pathways contribute to phenotype switching in endothelial and vascular smooth muscle cells of the affected artery, in which their physiological quiescent state is lost and replaced by a proliferative activated phenotype. Of interest, dissections in various anatomical locations are associated with distinct sex and age predilections, suggesting involvement of gene and environment interactions in disease pathogenesis. Importantly, these cellular mechanisms are potentially therapeutically targetable. Consideration of arterial dissections as a collective pathology allows insight from the better characterized dissection types, such as that involving the thoracic aorta, to be leveraged to inform the less common forms of dissections, including the potential to apply known therapeutic interventions already clinically available for the former.

Burden of Rare Genetic Variants in Spontaneous Coronary Artery Dissection With High-risk Features

Importance

The emerging genetic basis of spontaneous coronary artery dissection (SCAD) has been defined as both partially complex and monogenic in some patients, involving variants predominantly in genes known to underlie vascular connective tissue diseases (CTDs). The effect of these genetic influences has not been defined in high-risk SCAD phenotypes, and the identification of a high-risk subgroup of individuals may help to guide clinical genetic evaluations of SCAD.

Objective

To identify and quantify the burden of rare genetic variation in individuals with SCAD with high-risk clinical features.

Design, Setting, and Participants

Whole-exome sequencing (WES) was performed for subsequent case-control association analyses and individual variant annotation among individuals with high-risk SCAD. Genetic variants were annotated for pathogenicity by in-silico analysis of genes previously defined by sequencing for vascular CTDs and/or SCAD, as well as genes prioritized by genome-wide association study (GWAS) and colocalization of arterial expression quantitative trait loci. Unbiased genome-wide association analysis of the WES data was performed by comparing aggregated variants in individuals with SCAD to healthy matched controls or the Genome Aggregation Database (gnomAD). This study was conducted at a tertiary care center. Individuals in the Canadian SCAD Registry genetics study with a high-risk SCAD phenotype were selected and defined as peripartum SCAD, recurrent SCAD, or SCAD in an individual with family history of arteriopathy.

Main Outcomes and Measures

Burden of genetic variants defined by DNA sequencing in individuals with high-risk SCAD.

Results

This study included a total of 336 participants (mean [SD] age, 53.0 [9.5] years; 301 female participants [90%]). Variants in vascular CTD genes were identified in 17.0% of individuals (16 of 94) with high-risk SCAD and were enriched (OR, 2.6; 95% CI, 1.6-4.2; P = 7.8 × 10-4) as compared with gnomAD, with leading significant signals in COL3A1 (OR, 13.4; 95% CI, 4.9-36.2; P = 2.8 × 10-4) and Loeys-Dietz syndrome genes (OR, 7.9; 95% CI, 2.9-21.2; P = 2.0 × 10-3). Variants in GWAS-prioritized genes, observed in 6.4% of individuals (6 of 94) with high-risk SCAD, were also enriched (OR, 3.6; 95% CI, 1.6-8.2; P = 7.4 × 10-3). Variants annotated as likely pathogenic or pathogenic occurred in 4 individuals, in the COL3A1, TGFBR2, and ADAMTSL4 genes. Genome-wide aggregated variant testing identified novel associations with peripartum SCAD.

Conclusions and Relevance

In this genetic study, approximately 1 in 5 individuals with a high-risk SCAD phenotype harbored a rare genetic variant in genes currently implicated for SCAD. Genetic screening in this subgroup of individuals presenting with SCAD may be considered.

Genome-Wide Identification of Associations of Circulating Molecules With Spontaneous Coronary Artery Dissection and Aortic Aneurysm and Dissection

Circulating proteins play functional roles in various biological processes and disease pathogenesis. The aim of this study was to highlight circulating proteins associated with aortic aneurysm and dissection (AAD) and spontaneous coronary artery dissection (SCAD). We examined the associations of circulating molecule levels with SCAD by integrating data from a genome-wide association study (GWAS) of CanSCAD and 7 pQTL studies. Mendelian randomization (MR) analysis was applied to examine the associations between circulating molecule levels and AAD by using data from UK Biobank GWAS and pQTL studies. The SCAD-associated SNPs in 1q21.2 were strongly associated with circulating levels of extracellular matrix protein 1 (ECM1) and 25 other proteins (encoded by CTSS, CAT, CNDP1, KNG1, SLAMF7, TIE1, CXCL1, MBL2, ESD, CXCL16, CCL14, KCNE5, CST7, PSME1, GPC3, MAP2K4, SPOCK3, LRPPRC, CLEC4M, NOG, C1QTNF9, CX3CL1, SCP2D1, SERPINF2, and FN1). These proteins were enriched in biological processes such as regulation of peptidase activity and regulation of cellular protein metabolic processes. Proteins (FGF6, FGF9, HGF, BCL2L1, and VEGFA) involved in the Ras signaling pathway were identified to be related to AAD. In addition, SCAD- and AAD-associated SNPs were associated with cytokine and lipid levels. MR analysis showed that circulating ECM1, SPOCK3 and IL1b levels were associated with AAD. Circulating levels of low-density lipoprotein cholesterol and small very-low-density lipoprotein particles were strongly associated with AAD. The present study found associations between circulating proteins and lipids and SCAD and AAD. Circulating ECM1 and low-density lipoprotein cholesterol may play a role in the pathology of SCAD and AAD.

Association of Circulating Cathepsin B Levels With Blood Pressure and Aortic Dilation

Hypertension is a key risk factor for spontaneous coronary artery dissection (SCAD) and aortic dilation. Circulating proteins play key roles in a range of biological processes and represent a major source of druggable targets. The aim of this study was to identify circulating proteins that were associated with blood pressure (BP), SCAD and aortic dilation. We identified shared genetic variants of BP and SCAD in genome-wide association studies, searched for circulating protein affected by these variants and examined the association of circulating protein levels with BP, aortic aneurysm and dissection (AAD) and aortic diameters by integrating data from circulating protein quantitative trait loci (pQTL) studies and genome wide association study (GWAS) in individuals from the UK Biobank using two-sample Mendelian randomization analysis methods. Single nucleotide polymorphisms (SNPs) in JAG1, ERI1, ULK4, THSD4, CMIP, COL4A2, FBN1, FAM76B, FGGY, NUS1, and HNF4G, which were related to extracellular matrix components, were associated with both BP and SCAD. We found 49 significant pQTL signals among these SNPs. The regulated proteins were encoded by MMP10, IL6R, FIGF, MMP1, CTSB, IGHG1, DSG2, TTC17, RETN, POMC, SCARF2, RELT, and GALNT16, which were enriched in biological processes such as collagen metabolic process and multicellular organism metabolic process. Causal associations between BP and AAD and aortic diameters were detected. Significant associations between circulating levels of cathepsin B, a well-known prorenin processing enzyme, and BP and aortic diameters were identified by using several Mendelian randomization analysis methods and were validated by independent data.

mTOR signaling-related microRNAs as cardiac hypertrophy modulators in high-volume endurance training

Aerobic exercise training (ET) promotes cardiovascular adaptations, including physiological left ventricular hypertrophy (LVH). However, the molecular mechanisms that underlying these changes are unclear. The study aimed to elucidate specific miRNAs and target genes involved with the Akt/mTOR signaling in high-volume ET-induced LVH. Eight-week-old female Wistar rats were assigned to three groups: sedentary control (SC), trained protocol 1 (P1), and trained protocol 2 (P2). P1 consisted of 60 minutes/day of swimming, 5x/week, for 10 weeks. P2 consisted of the same protocol as P1 until the 8^th week; in the 9^th week, rats trained 2x/day, and in the 10^th week, trained 3x/day. Subsequently, structure and molecular parameters were evaluated in the heart. Trained groups demonstrate higher values to VO₂ peak, exercise tolerance, and LVH in a volume-dependent manner. The miRNA-26a-5p levels were higher in P1 and P2 compared to SC group (150±15%, d=1.8; 148±16%, d=1.7; and 100±7%, respectively, P < 0.05). In contrast, miRNA-16-5p levels were lower in P1 and P2 compared to SC group (69±5%, d=2.3, P < 0.01; 37±4%, d=5.6, P < 0.001 and 100±6%, respectively). Additionally, miRNA-16-5p knockdown and miRNA-26a-5p overexpression significantly promoted cardiomyocyte hypertrophy in neonatal rat cardiomyocytes. Both miRNAs were selected, using Diana Tolls bioinformatics website, for acting in the mTOR signaling pathway. The protein expression of Akt, mTOR, p70^S6k, and 4E-BP1 were greater in P1 and even more pronounced in P2. Nonetheless, GSK3β protein expression was lower in trained groups. Together, these molecular changes may contribute to a pronounced physiological LVH observed in high-volume aerobic training.

Spontaneous coronary artery dissection: Overview of pathophysiology

The growing use of imaging examinations has led to increased detection of spontaneous coronary artery dissection (SCAD) as a non-atherosclerotic cause of acute coronary syndrome (ACS). Since a greater awareness of pathophysiologic mechanisms has relevant implications in clinical practice, we aim to provide an update to current knowledge of SCAD pathophysiology. We discuss the most common conditions associated with SCAD, including predisposing factors and triggers, and focus on potential mechanisms leading to SCAD development. Furthermore, we report the main genetic research findings that have shed further light on SCAD pathophysiology. Finally, we summarize practical considerations in SCAD management based on pathophysiologic insights.