Circulation: Genomic and Precision Medicine

BackgroundPolygenic risk scores derived from coronary artery disease genome-wide association studies are associated with statin relative risk reduction. ObjectiveExamine the relationship between coronary artery disease polygenic risk scores that include variants below thresholds of genome-wide significance and statin primary prevention of major adverse cardiovascular events. MethodsWe generated coronary artery disease polygenic risk scores for participants with no past evidence of myocardial infarction from three electronic health record-linked genetic biobanks: All of Us Research Program, Genetic Epidemiology Research on Adult Health and Aging, and the Million Veteran Program. We scored each participant using three different polygenic risk scores: two with both genome-wide and sub-genome-wide significant variants (metaGRS and PRS2022) and one with only variants meeting genome-wide significance (164SNP). We used covariate-adjusted Cox regression models to compare risk of major adverse cardiovascular events between statin users and nonusers matched on age, sex, smoking status, type 2 diabetes mellitus, and hypertension within strata defined by polygenic risk. For the primary analysis, we performed a meta-analysis across the three cohorts for the delta hazard ratio of statin effectiveness between high and low polygenic risk. ResultsAcross all cohorts, statin use was more strongly associated with reduced risk of major adverse cardiovascular events among participants with no myocardial infarction at index in the highest versus lowest polygenic risk score group for the PRS2022 (interaction beta 0.19, standard error 0.07, interaction P=2.3E-3) and metaGRS (interaction beta 0.14, standard error 0.07, interaction P=.02) scores. However, the association was not statistically significant (interaction beta 0.09, standard error 0.07, interaction P=.08) for the 164SNP risk score. ConclusionsWe demonstrated that the association between coronary artery disease polygenic risk scores and statin relative risk reduction can by enhanced with the inclusion of sub-genome-wide variants, paving the way for more research to establish clinical utility.

BackgroundAnnually 300,000 Americans experience sudden cardiac arrest (SCA). Studies in referral SCA cohorts have observed rare variants in genes associated with arrhythmia and cardiomyopathy. We sought to: (1) establish the population prevalence of rare disease-causing variants in a set of candidate genes and (2) confirm the association of disease-causing variants in these genes with SCA in two prospective population-based studies. MethodsSCA patients (n=3264) were accrued from the Oregon Sudden Unexpected Death Study and the PREdiction of Sudden death in mulTi-ethnic cOmmunities (PRESTO) study and compared to control patients (n=13713) from the Atherosclerosis Risk in Communities (ARIC) study. Whole genome sequencing was performed. Disease-causing (likely pathogenic or pathogenic) variants in candidate genes associated with arrhythmia/cardiomyopathy were identified using updated American College of Medical Genetics and Genomics criteria. Gene- collapsing case-control analysis was performed using the conditional logistic regression-sequence kernel association test. ResultsWe identified 300 disease-causing variants, the majority of which were in cardiomyopathy genes (71%). There were 136 patients (4.2%) in the SCA group and 351 patients (2.6%) in the control group with one or more disease-causing variants (OR 1.66, 95% confidence interval 1.33-2.07, p<0.001). We identified 13 genes associated with an increased risk of SCA, nine associated with cardiomyopathy (BAG3, DSC2, DSG2, FLNC, LMNA, MYBPC3, TNNI3, TNNT2, TTN) and four with arrhythmia (CACNA1C, CASQ2, KCNH2, KCNQ1). ConclusionsDisease-causing variants in cardiomyopathy genes were the predominant genetic cause of SCA. These findings inform which genes to include in genetic screening for SCA.

Background and Aims: Polygenic risk scores (PRSs) for atherosclerotic cardiovascular disease (ASCVD) can perform equivalently at the population level yet disagree for individual patients. We examined whether such intra-individual variability reflects genuinely complementary risk information or mainly statistical and methodological uncertainty, and whether it affects clinical classification once PRSs are integrated into SCORE2-OP. Methods: In 4,137 ASCVD-free participants of the CoLaus|PsyCoLaus cohort (478 incident events over a median 14.4 years), we identified 16 ASCVD-PRSs with practically equivalent population-level performance using Bayesian equivalence testing. We quantified intra-individual variability (standard deviation, coefficient of variation, intraclass correlation, Cohen's kappa, extreme discordance), tested whether discordance exceeded chance, decomposed scores into shared and unique genetic components, and assessed variability after integration into SCORE2-OP, benchmarked against perturbation of systolic blood pressure. Results: For a typical individual, risk estimates varied by 18 percentile points across PRSs. Discordance matched chance expectations under a shared-signal model, with no distinct phenotypic profile among discordant individuals, and predictive power resided overwhelmingly in the shared genetic component. Variability tracked PRS size and weighting rather than distinct variants. After integration into SCORE2-OP, 75.6% of participants were placed in different categories by at least one model and 54.6% as both low and high risk; instability was concentrated near guideline thresholds and far exceeded that from blood-pressure measurement error. Conclusions: Equivalent population-level performance is not sufficient to treat PRSs as interchangeable at the individual level, and methodological standardisation and pragmatic clinical trials remain necessary to determine whether PRS integration improves long-term cardiovascular outcomes.

Congenital heart disease (CHD) occurs in over half of individuals with 22q11.2 deletion syndrome (22q11.2DS) and the types of lesions range from mild to severe. To determine the basis of variation in cardiac phenotypes we analyzed demographic data from 3,016 unrelated individuals with 22q11.2DS from centers in the Northeast US, Canada, Europe, South America, Israel and Australia. Most individuals in this cohort had a 3 million base pair hemizygous deletion between low copy repeat, LCR22 A-D (87.2%), while some had nested deletions. We performed multivariable mixed-effects logistic regression and uncovered significant differences between CHD phenotypes and basic demographic features. Individuals with the A-D deletion had a lower risk of persistent truncus arteriosus (OR = 0.37, 95% CI 0.18-0.75) but a higher risk of septal defects (OR = 4.7, 95% CI 1.7-12.8) compared to those with the smaller A-B deletion, suggesting distinct developmental pathways sensitive to 22q11.2 gene dosage. In addition, genome-wide genetic principal components (PCs) were associated with specific CHD subtypes, including reduced risk of pulmonary stenosis or atresia with other heart lesions (PC2; OR = 0.73, 95% CI 0.61-0.87) and increased risk of abnormal origin of the subclavian arteries (PC4; OR = 2.6, 95% CI 1.4-4.9), indicating that background genetic variation modifies heart lesion-specific susceptibility. Together, these results suggest that both deletion size and background genetic variation shape the highly variable cardiac phenotypes in 22q11.2DS.

Background: Cardiovascular disease (CVD) is the leading cause of mortality in New Zealand, with significant inequities affecting M[a]ori and Pacific peoples. Familial hypercholesterolaemia (FH) affects approximately 1 in 313 individuals globally, yet over 90% remain undiagnosed. Standard polygenic risk scores (PRS) derived from European cohorts may not be portable to diverse ancestries. We developed the HoloQ Omniscan Waka Te Ira, a custom Illumina Global Screening Array (GSA) v3 enriched with FH mutations, coronary artery disease (CAD) PRS markers, and network medicine-derived content. Methods: We customised the GSA v3 by adding 43,437 single nucleotide polymorphisms (SNPs) targeting FH and CAD. Content included 6,717 unique variants in primary FH genes; 14,005 pathogenic or likely pathogenic cardiovascular and pharmacogene variants; and 5,845 copy number variant probes. We further incorporated 5,232 network medicine derived CAD SNPs, 14,806 rare variants for a multiancestry PRS, and 407 globally diverse and population-specific variants. The final design comprised 47,027 target SNPs. Validation utilised large-scale genotype and whole-genome sequencing (WGS) datasets with PRS benchmarking. Results: In a large European-ancestry dataset, we observed high recovery for common PRS loci but low recovery for population-specific founder variants. The array captured 938 (84%) of all pathogenic or likely pathogenic FH variants catalogued in ClinVar, representing a 26.4% expansion beyond the standard backbone array. WGS validation identified additional carriers of rare high impact variants present only in the custom content. The selected CAD PRS model achieved an adjusted area under the receiver operating characteristic curve of 0.786. Conclusion: The HoloQ Omniscan Waka Te Ira enhances detection of clinically relevant FH variants and provides robust PRS coverage. The low recovery of population-specific alleles underscores the necessity of this custom array for equitable genomic medicine in New Zealand's multi-ethnic population.

ImportanceThe effect of high percentage spliced in (hiPSI) TTN truncating variants (TTNtvs) on risk of dilated cardiomyopathy (DCM) has historically been studied among population subgroups defined by genetic similarity to European reference populations. This has raised questions about the effect of TTNtvs in diverse populations, especially among individuals genetically similar to African reference populations. ObjectiveTo determine the effect of TTNtvs on risk of DCM in diverse population as measured by genetic distance (GD) in principal component (PC) space. DesignCohort study SettingPenn Medicine Biobank (PMBB) is a large, diverse biobank. ParticipantsParticipants were recruited from across the Penn Medicine healthcare system and volunteered to have their electronic health records linked to biospecimen data including DNA which has undergone whole exome sequencing. Main Outcomes and MeasuresRisk of DCM among individuals carrying a hiPSI TTNtv. ResultsCarrying a hiPSI TTNtv was associated with DCM among PMBB participants across a range of GD deciles from the 1000G European centroid; the effect estimates ranged from odds ratio (OR) = 3.29 (95% confidence interval [CI] 1.26 to 8.56) to OR = 9.39 (95% CI 3.82 to 23.13). When individuals were assigned to population subgroups based on genetic similarity to the 1000G reference populations, hiPSI TTNtvs conferred significant risk of DCM among those genetically similar to the 1000G European reference population (OR = 7.55, 95% CI 4.99 to 11.42, P<0.001) and individuals genetically similar to the 1000G African reference population (OR 3.50, 95% CI 1.48 to 8.24, P=0.004). Conclusions and RelevanceTTNtvs are associated with increased risk of DCM among a diverse cohort. There is no significant difference in effect of TTNtvs on DCM risk across deciles of GD from the 1000G European centroid, suggesting genetic background should not be considered when screening individuals for titin-related DCM. Key Points QuestionDo high percentage spliced in (hiPSI) titin truncating variants (TTNtvs) confer similar levels of risk for dilated cardiomyopathy (DCM) across diverse populations? FindingsIn a cohort study that comprised 43,731 individuals of diverse genetic background with electronic health records linked to whole exome sequencing data, hiPSI TTNtvs conferred increased risk of DCM across all individuals irrespective of genetic background as measured by genetic distance from the 1000 Genomes Project European centroid. MeaningThe findings of this study suggest that TTNtvs increase risk of DCM among individuals independent of genetic background and that genetic similarity to a reference population should not play a role in screening for genetic causes of dilated cardiomyopathy.

BackgroundInherited cardiomyopathies can present with broad variation of phenotype. Data are limited regarding genetic screening strategies and outcomes associated with putative pathogenic variants (PuPV) in cardiomyopathy-associated genes in the general population. ObjectiveWe aimed to determine the risk of mortality and cardiomyopathy-related outcomes associated with PuPV in cardiomyopathy-associated genes in UK Biobank. MethodsUsing whole exome sequencing data, variants in dilated, hypertrophic and arrhythmogenic cardiomyopathy-associated genes with at least limited evidence of disease causality according to ClinGen Expert Panel curations, were annotated using REVEL ([&ge;]0.65) and ANNOVAR (predicted loss of function) to identify PuPVs. Individuals with PuPV comprised the genotype-positive (G+) and those without PuPV the genotype-negative (G-) cohorts. Group comparisons were made using time-to-event analyses for the primary (all-cause mortality) and secondary outcomes (diagnosis of cardiomyopathy; composite outcome of diagnosis of cardiomyopathy, heart failure, arrhythmia, stroke, and death). ResultsAmong 200,619 participants, 22,401 (11.2%) were found to host [&ge;]1 PuPV in cardiomyopathy-associated genes (G+). After adjusting for age and sex, G+ individuals had increased all-cause mortality [HR 1.07 (95%CI 1.02-1.13; p=0.011)] and increased rates of diagnosis of cardiomyopathy later in life [HR 2.37 (95%CI 1.98-2.85; p<0.0001)], which further increased in those with PuPV in definitive/strong evidence ClinGen genes [3.25 (95%CI 2.63-4.00; p<0.0001)]. G+ individuals had a higher risk of developing the composite outcome [HR 1.11 (95%CI 1.06-1.15; p<0.0001)]. ConclusionsAdults with PuPV in cardiomyopathy-associated genes have higher all-cause mortality and increased risk of developing cardiomyopathy-associated features and complications, compared to genotype-negative controls. Condensed AbstractLeveraging the UK Biobank prospective cohort, we analyzed whole exome sequencing data in dilated, hypertrophic and arrhythmogenic cardiomyopathy-associated genes using a population screening genotype-first approach. Individuals with putative pathogenic variants in genes implicated in cardiomyopathies showed an increased risk of all-cause mortality, higher risk of developing clinical cardiomyopathy later in life, and higher risk of a composite outcome (cardiomyopathy, heart failure, arrhythmia, stroke, and death) compared to genotype-negative controls. These findings highlight the potential role of genotype-first approach in elevating personalized medicine into population level precision health in the future.

Polygenic scores (PGS) have emerged as important modifiers of disease risk, drug response, and rare variant penetrance, but the biological mechanisms underlying these associations remain poorly understood. To experimentally investigate these relationships, we derived induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from individuals at the 1st, 50th, and 99th percentiles of a genome-wide QT interval polygenic score (QT-PGS). We examined baseline repolarization, drug response to the hERG inhibitor E4031, and penetrance of two KCNH2 variants (p.Arg148Trp and p.Arg823Trp) in these cellular models. While baseline field potential durations (FPDs) did not differ across PGS levels, high-PGS iPSC-CMs showed exaggerated prolongation in response to E4031 and increased phenotypic expression of both KCNH2 variants. These findings provide the first experimental demonstration that polygenic background can shape cardiac electrophysiologic phenotypes and modulate the functional impact of both pharmacologic and genetic perturbations. This work establishes a scalable platform for mechanistic studies of polygenic risk.

Background: The clinical significance of sarcomere variants of uncertain significance (VUS) in hypertrophic cardiomyopathy (HCM) remains unclear, and VUS are currently regarded as clinically non-actionable despite their increasing prevalence. This study aimed to evaluate genotype?phenotype and genotype?outcome associations according to variant pathogenicity in patients with HCM, with a particular focus on the clinical relevance of sarcomere VUS. Methods: This multicenter retrospective cohort study included 438 patients with HCM who underwent next-generation sequencing-based genetic testing at two tertiary hospitals. Patients were classified into three groups: pathogenic or likely pathogenic (P/LP) variants, VUS, and no sarcomere mutations. Clinical characteristics, imaging phenotypes, and outcomes were compared across groups. The primary endpoint was a composite of cardiovascular death, aborted sudden cardiac death, appropriate implantable cardioverter-defibrillator therapy, and heart transplantation. Time-to-event analyses were performed using Kaplan-Meier methods and Cox proportional hazards models with Firth's penalized partial likelihood approach. Results: P/LP variants were identified in 171 patients (39.0%) and sarcomere VUS in 159 patients (36.3%). Patients with VUS demonstrated intermediate clinical and phenotypic features between P/LP carriers and genotype-negative patients. Kaplan?Meier analysis showed a graded difference in event-free survival across variant classifications. While VUS were not independently associated with adverse outcomes when modeled as a categorical variable, increasing pathogenicity from genotype-negative to VUS and P/LP variants was associated with a stepwise increase in risk of the primary endpoint (hazard ratio 2.05, 95% confidence interval 1.11?4.16 p=0.019). Identified VUS were preferentially enriched in Z-disc and giant sarcomere scaffolding proteins. Conclusion: Sarcomere VUS represent intermediate characteristics along a continuum of sarcomere dysfunction, associated with distinct phenotypic features and clinical outcomes compared with both P/LP variants and the absence of sarcomere mutations. These findings suggest that sarcomere VUS may not be entirely clinically neutral and should be interpreted within a broader genetic and structural context in patients with HCM.

BackgroundThoracic aortic aneurysm and dissection (TAAD) can have catastrophic health consequences. Eleven genes have strong or definitive evidence for causing heritable TAAD (HTAAD). However, patients are seldom tested for rare pathogenic (P) or likely pathogenic (LP) variants in these HTAAD genes absent a strong family history or syndromic features, and little is known about either their prevalence in the general population or the associated TAAD risk. Furthermore, the degree to which common genetic variation associated with TAAD modifies rare variant pathogenicity is unknown. MethodsPenn Medicine Biobank (PMBB) and MyCode participants volunteered to have electronic health records linked to biospecimen data including DNA which has undergone genome-wide genotyping and whole exome sequencing. P/LP HTAAD gene variants were adjudicated according to American College of Medical Genetics and Genomics standards, and logistic regression was performed to determine the associated risk of prevalent TAAD. An ascending aortic diameter (AscAoD) polygenic risk score (PRS) was derived from a genome-wide association study (GWAS) of aortic diameter to assess common variant TAAD risk, and regression analyses were performed to determine the modifying effect this PRS had on penetrance of rare variants. ResultsAcross the two analytic cohorts, 0.2-0.3% of participants carried a P/LP HTAAD gene variant. Compared to individuals without a P/LP variant, carrying a P/LP HTAAD variant was associated with a 13.5-fold increased risk of a diagnosis of TAAD (95% confidence interval [CI] 5.3 to 34.6, P<0.001) with variable effects when stratified by gene. A one standard deviation increase in the AscAoD PRS was associated with a 1.43-fold increased risk of TAAD (95% CI 1.39 to 1.47, P<0.001). TAAD prevalence was higher among individuals carrying a P/LP HTAAD gene variant in the highest PRS quintile compared to carriers in the lowest PRS quintile (relative risk = 2.32, 95% CI 1.29 to 4.17, P<0.01) suggesting that common variant risk may be an important modifier of rare variant risk for TAAD. ConclusionsOur results indicate that P/LP HTAAD gene variants confer a significant increased risk of TAAD in the population at-large, and that polygenic risk may be an important modifier of rare variant risk.

2.TEXT ABSTRACT AND KEYWORDSO_ST_ABSBackground and AimsC_ST_ABSPeople with monogenic familial hypercholesterolaemia (FH) are at an increased risk of premature coronary heart disease and death. Currently there is no population screening strategy for FH, and most carriers are identified late in life, delaying timely and cost-effective interventions. The aim was to derive an algorithm to improve detection of people with monogenic FH. MethodsA penalised (LASSO) logistic regression model was used to identify predictors that most accurately identified people with a higher probability of FH in 139,779 unrelated participants of the UK Biobank, including 488 FH carriers. Candidate predictors included information on medical and family history, anthropometric measures, blood biomarkers, and an LDL-C polygenic score (PGS). Model derivation and evaluation was performed using a random split of 80% training and 20% testing data. ResultsA 14-variable algorithm for FH was derived, where the top five variables included triglyceride, LDL-C, and apolipoprotein A1 concentrations, self-reported statin use, and an LDL-C PGS. Model evaluation in the test data resulted in an area under the curve (AUC) of 0.77 (95% CI: 0.71; 0.83), and appropriate calibration (calibration-in-the-large: -0.07 (95% CI: -0.28; 0.13); calibration slope: 1.02 (95% CI: 0.85; 1.19)). Employing this model to prioritise people with suspected monogenic FH is anticipated to reduce the number of people requiring sequencing by 88% compared to a population-wide sequencing screen, and by 18% compared to prioritisation based on LDL-C and statin use. ConclusionsThe detection of individuals with monogenic FH can be improved with the inclusion of additional non-genetic variables and a PGS for LDL-C.

Importance Dilated cardiomyopathy (DCM) is a major cause of heart failure that disproportionately affects individuals of African genetic ancestry (AFR), among whom familial clustering of disease is also more pronounced relative to those of European ancestry (EUR). However, established monogenic DCM genes, identified primarily in EUR populations, explain a smaller proportion of DCM cases in AFR populations. A recent study identified a common AFR-specific nonsense variant in CD36 that accounts for a substantial burden of DCM in AFR. How the risk and population impact of this variant compare with those of established genetic causes of DCM is unknown. Objective To compare the contribution of a CD36 nonsense variant to DCM risk with that of truncating variants in TTN and pathogenic or likely pathogenic (P/LP) variants in other established DCM genes. Design, Setting, and Participants Multicohort genetic association study including AFR and EUR participants with exome or genome sequence and DCM case status from four datasets: All of Us, Million Veteran Program, Penn Medicine Biobank, and the DCM Precision Medicine Study. Exposure Carrier status for TTN truncating variants, P/LP variants in 11 high confidence DCM genes, and the CD36 nonsense variant (Y325*; 0, 1, or 2 copies). Main Outcomes and Measures Odds of DCM; prevalence of risk-variant carriers among DCM cases; and population attributable fraction (PAF) for DCM. Results Among 82,623 AFR individuals across four studies, the mean age was 53.4 years and 1,625 had DCM. CD36 Y325* risk-allele homozygotes had 4.8-fold (95% CI, 3.1-7.3) increased odds of DCM, and CD36 Y325* heterozygotes had 1.4-fold (95% CI, 1.2-1.7) increased odds. TTN truncating variants also conferred elevated risk of DCM in AFR participants (OR, 8.46; 95% CI, 5.3-12.3). Among AFR DCM cases, 2.5% were CD36 homozygotes, second only to TTN truncating variants (4.3%) and exceeding all other high-confidence DCM genes combined (1.5%). In population-level analyses incorporating both heterozygous and homozygous CD36 Y325* carriers, the population-attributable fraction for CD36 (9.0%) surpassed that of TTN truncating variants (3.6%). Conclusions and Relevance An ancestry-specific CD36 variant contributes more to DCM burden in AFR ancestry than established DCM genes, including TTN truncating variants, typically considered the most common genetic cause of DCM. These findings reshape the known genetic architecture of DCM in individuals of African ancestry and highlight the importance of representation in genomic research.

BackgroundEvidence of the diverse genetic architecture of dilated cardiomyopathy (DCM) continues to emerge and requires reassessment of the clinical relevance of implicated disease genes. Building on the 2019-2020 Clinical Genome Resource (ClinGen) evaluation, the DCM Gene Curation Expert Panel (GCEP) reconvened in 2024-2025 to conduct a reassessment of genes in DCM. MethodsThe ClinGen semi-quantitative clinical validity classification framework was applied with specifications to DCM to classify genes into categories based upon strength of published evidence for a DCM phenotype. Previously curated genes were reassessed and newly reported gene-disease-mode of inheritance (MOI) relationships, termed "curations," were evaluated. ResultsSixty-eight genes were evaluated, inclusive of 72 unique gene-disease-MOI relationships across 51 previously evaluated and 17 newly assessed genes. Thirty-five curations were classified as high evidence (16 Definitive, 10 Strong, 9 Moderate), increasing by 16 from the prior assessment. Nine newly assessed genes were classified as high evidence, including BAG5, FLII, LMOD2, MYLK3, MYZAP, NRAP, PPA2, PPP1R13L, and RPL3L. Twelve genes (11 newly appraised) were rated as high evidence with an autosomal recessive (AR) MOI. Five re-evaluated genes from 2019-2020 had clinically significant changes in classification. Except for JPH2, for which curation was modified to separate autosomal dominant (-AD) and -AR MOI curations, clinically significant changes involved upgrades from low to high evidence categories (PLEKHM2, PRDM16, TBX20, TNNI3K), demonstrating the robustness of the ClinGen gene curation process over time. An additional 29 gene-disease-MOI curations were classified as Limited, including six newly evaluated genes and one new MOI for a previously evaluated gene, MYBPC3-AR; four were classified as No Known Disease Relationship, and four remained Disputed. Four previously evaluated genes were curated for both AD and AR MOIs, including JPH2 (AD-Strong, AR-Limited), LDB3 (AD-Limited, AR-Strong), MYBPC3 (AD-Limited, AR-Limited), and TNNI3 (AD- and AR- Strong). ConclusionsWith substantial new evidence, the genetic architecture of DCM has rapidly expanded. This updated assessment of genes reported in DCM yielded 35 high evidence curations, an increase from 19 only five years ago. The results of this evidence-based evaluation process informs clinical interpretation of genetic information in the care of DCM patients and families. CLINICAL PERSPECTIVEO_ST_ABSWhats new?C_ST_ABSO_LIThe Clinical Genome Resource (ClinGen) Dilated Cardiomyopathy (DCM) Gene Curation Expert Panel reconvened to update the evidence for genes in DCM using the ClinGen clinical validity framework. C_LIO_LIA total of 35 genes were classified into clinically actionable, high evidence categories of Definitive, Strong, or Moderate evidence, an increase of 16 from the 2019-2020 curation. C_LIO_LIOf the 16 newly classified high evidence curations, 11 (69%) had an autosomal recessive mode of inheritance and were observed primarily in pediatric DCM. C_LI What are the clinical implications?O_LIThis update has substantially expanded the complex and diverse genetic architecture of DCM spanning 18 gene ontologies (8 new) identified in both adult and pediatric patients. C_LIO_LIThe 19 genes classified as high evidence in the 2019-2020 curations were adopted by the clinical genetics community as the key genes for clinical genetic testing and care for DCM patients and families. The 35 high evidence curations from the current assessment are recommended to be used as an updated list for clinical genetics care for DCM. C_LIO_LIDCM gene curation will require ongoing reassessments due to the continuing expansion of high-quality research data. C_LI

BackgroundVariant interpretation can change over time as new knowledge emerges. Our aim was to determine the frequency and causes of variant reinterpretation on systematic re-evaluation in pediatric patients with cardiomyopathy. MethodsOverall, 227 unrelated pediatric patients with cardiomyopathy enrolled in the Heart Centre Biobank harbored a pathogenic/likely pathogenic (P/LP) variant and/or a variant of uncertain significance (VUS) on clinical genetic testing (2005-2022). Variant pathogenicity was re-evaluated using the American College of Medical Genetics and Genomics (ACMG) guidelines. Additional extension cohorts (n=4547, cases) were analyzed to assess variant burden in cases versus controls (gnomAD 4.1.0). Results382 variants (110 P/LP, 272 VUS) in 227 patients were re-evaluated. Forty-nine variants in 49 patients (21.6%) changed classification. Twelve (10.9%) P/LP variants were downgraded to VUS in 14 patients. Leading criteria were high population allele frequency and variant not located in mutational hotspot or critical functional gene domain. Thirty-seven (13.6%) VUS were upgraded to P/LP in 35 patients. Leading criteria were variant location in mutational hotspot for gene, and deleteriousness on in silico prediction. Only 8 reclassified variants had been reported back by the clinical genetic testing laboratory at the time of the study. Ten of the 37 VUS upgraded to P/LP were significantly enriched in cardiomyopathy cases (n=4796) versus controls. ConclusionsOne in five patients with cardiomyopathy had a clinically relevant change in variant pathogenicity on systematic re-evaluation that would require modifying family clinical screening and cascade genetic testing. These findings underscore the clinical importance of regular variant re-interpretation on follow-up.

Congenital heart disease (CHD) is the most common birth defect. We performed Illumina short-read genome sequencing (GS) of 1,101 probands, which identified a genetic cause in 16% of cases. We performed PacBio long-read GS in 43 genotype-elusive patients. Paired analysis revealed higher detection with long-read GS of single nucleotide variants, deletions, duplications, and insertions as well as fewer false-positives for indels and inversions. Long-read GS had higher coverage of nine CHD genes, but a low sequencing depth (<10x) in intragenic regions of four of these genes. Long-read GS was better able to resolve complex structural variants and the size of large repeat expansions in 59 known disease-causing regions. This included a complex de novo structural variant upstream of ZEB2 that was only resolved with long-read GS in a patient with extra-cardiac phenotype overlapping Mowat-Wilson syndrome. Long-read GS may provide an option in CHD patients who remain genotype-elusive on short-read GS.

BackgroundA coronary artery calcium (CAC) score of 0 is widely considered to indicate low short- to intermediate-term risk for coronary artery disease (CAD) and is frequently used to defer lipid-lowering therapy. However, a subset of individuals with CAC=0 still experience events, highlighting residual risk not captured by imaging alone. Polygenic risk scores (PRS) quantify lifelong inherited susceptibility, but conventional approaches rely on predefined ancestry labels despite human genetic diversity existing along a continuum. To address this limitation, we developed 8 Billion, a novel, label-free framework that models genetic similarity without pre-labeling individuals by ancestry. We evaluated whether a CAD PRS derived using this approach identifies clinically meaningful residual risk among individuals with baseline CAC=0. MethodsWe analyzed participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with baseline CAC=0. The 8 Billion framework estimates individualized PRS by anchoring each participant to a genetically similar reference neighborhood rather than discrete ancestry groups. Multivariable Cox proportional hazards models assessed associations between PRS-defined risk groups and incident CAD, adjusting for principal components of genetic variation (PC1-PC4), age, sex, smoking status, systolic blood pressure, total and high-density lipoprotein cholesterol, diabetes, and antihypertensive medication use. Two classifications were evaluated: (1) a Top 5% group defined by the highest 5% of PRS-derived odds ratios in the cohort; and (2) an individualized high-risk group defined using a personalized threshold derived from the 8 Billion framework. Ten-year absolute risk estimates were derived from adjusted models. ResultsDespite CAC=0 at baseline, polygenic burden was independently associated with incident CAD. Individuals in the Top 5% PRS group had higher risk of CAD events compared with the remainder (hazard ratio [HR], 3.12; 95% CI, 1.05-9.31; P=0.041). The individualized high-risk group defined through 8 Billion was similarly associated with increased CAD risk (HR, 2.52; 95% CI, 1.12-5.66; P=0.025). Estimated 10-year ASCVD risk among high-PRS individuals exceeded the 7.5% threshold commonly used to guide initiation of lipid-lowering therapy, despite CAC=0. In fully adjusted models, conventional risk factors were not statistically significant within this subset. ConclusionsAmong individuals with CAC=0 in a multi-ethnic cohort, a label-free, ancestry-continuum PRS approach identified subgroups at significantly increased risk of incident CAD and at guideline-relevant 10-year treatment thresholds. Integration of polygenic risk with CAC imaging refines preventive decision-making beyond imaging alone. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIAmong individuals with baseline CAC=0, the Allelica Multi-ancestry CAD PRS calculated with the 8 Billion framework identified subgroups at significantly increased risk of incident CAD. C_LIO_LIIn this CAC=0 population, high polygenic risk was associated with 10-year risk estimates above the 7.5% treatment threshold, whereas conventional risk factors were not statistically significant in adjusted models. C_LI What are the clinical implications?O_LIA CAC score of 0 should not be interpreted as uniformly protective, because genetically high-risk individuals may still experience clinically meaningful coronary events. C_LIO_LIIntegrating PRS with CAC assessment may improve preventive decision-making by identifying patients with residual risk despite reassuring baseline imaging. C_LIO_LIIn selected patients with CAC=0, high polygenic risk may support closer follow-up and earlier consideration of lipid-lowering therapy or other preventive strategies and imaging modalities. C_LI

Background. Polygenic scores (PRS) for coronary artery disease (CAD) are derived almost entirely from European-ancestry data. Their portability to Southeast Asian populations, including the Vietnamese, is largely uncharacterised and clinically consequential when scores are used with risk thresholds. Methods. We evaluated four independent European-derived CAD scores from the PGS Catalog (PGS000058, PGS000349, PGS002809, PGS004198; 70 - 5,723 variants) in 2,504 individuals from the 1000 Genomes Project, focusing on the Vietnamese Kinh (KHV) and Dai (CDX) samples. Per-individual scores were computed with PLINK2 and standardised. We assessed (i) the cross-ancestry distribution (calibration) and (ii) a clinically-relevant consequence: the proportion of each population flagged high genetic risk when the European top-20% threshold is applied (20% if perfectly calibrated). Results. For the primary score (PGS000058) the standardised PRS differed across super-populations (ANOVA F(4, 2499) = 121.1, p < 0.001); the Vietnamese Kinh mean was +0.47 SD above the European mean (Welch t = 7.77, p = 2.0 x 10^ -14). Applying the European top-20% high-risk threshold, the fraction of Vietnamese Kinh flagged ranged from 22.2% to 57.6% across the four scores, and of Dai from 21.5% to 43.0%, versus the intended 20%. Three of the four scores over-flagged Vietnamese (25-58%); the largest score (PGS004198) was approximately calibrated for East/Southeast Asians ([~]22%) but markedly over-flagged Africans (69.3%). Conclusions. European-derived CAD polygenic scores are inconsistently calibrated in Vietnamese and other Southeast Asian samples, and most substantially over-flag high genetic risk when a European threshold is applied. The magnitude and even the direction of miscalibration depend on the specific score, so no such score can be assumed transferable without local validation and recalibration. Distribution shift bounds, but does not by itself quantify, loss of predictive accuracy, which requires phenotyped data.

BackgroundL-2-hydroxyglutarate dehydrogenase (L2HGDH) deletion-induced L-2-hydroxyglutarate accumulation plays a cardioprotective role in hypoxic conditions. However, there has been no causal evidence in real-world clinical data. We aimed to examine the causal effects of L2HGDH inhibition on coronary artery disease (CAD) and myocardial infarction (MI) using Mendelian randomization (MR) analysis. MethodsWe used nine L2HGDH-proxied genetic variants associated with blood 2-hydroxyglutarate levels as genetic instruments, and performed two-sample MR analysis using the CARDIoGRAMplusC4D meta-analysis datasets of CAD (60,801 CAD cases and 123,504 controls) and MI (34,541 MI cases and 261,984 controls). ResultsGenetically proxied inhibition of L2HGDH associated with 2-hydroxyglutarate levels potentially decreased the risk of CAD (odds ratio [OR] 0.486, 95% confidence interval [CI] 0.242-0.977, P=0.043) but was not associated with the risk of MI (OR 0.676, 95% CI 0.312-1.463, P=0.320). This potentially causal association between L2HGDH inhibition and CAD was unlikely to be biased by horizontal pleiotropy, whereas there might be a weak instrument bias. ConclusionOur MR analysis suggests the potential association between genetically proxied inhibition of L2HGDH and CAD. Our findings may have therapeutic implications for L2HGDH inhibitors in CAD, and further large-scale clinical studies are needed.

BACKGROUNDHereditary transthyretin amyloid cardiomyopathy (ATTRv-CM) is being increasingly diagnosed due to enhanced awareness and availability of newer therapeutics. Multiple TTR variants have been described worldwide, but with uncertain disease penetrance. The characteristics and outcomes of "previously undiagnosed" pathogenic-likely pathogenic (P/LP) TTR variant (genotype or G+; cardiac phenotype or P-) carriers are unknown which has important prognostic and therapeutic implications, especially for affected family members. This descriptive study aimed to delineate phenotype and cardiac penetrance in "previously undiagnosed" G+P-family members of ATTRv probands. METHODSDemographic, electrocardiographic (ECG), genetic, and imaging (echocardiography, cardiac technetium-99m pyrophosphate (PYP) and magnetic resonance imaging) data were analyzed. The prediction effect of selected baseline characteristics for ATTRv-CM development was evaluated. Kaplan-Meier and Cox regression methods were used to describe risk and predictors of ATTRv-CM development in family members. RESULTSThere were 85 G+P-family members identified. Mean age was 48.5{+/-}11.7 years, 39% were male, 18% had a diagnosis of peripheral neuropathy, 15% with a history of carpal tunnel syndrome, and 4% had atrioventricular block at baseline. Of these, 55 patients had follow-up imaging studies. After a median 6.8-year follow-up, 22% developed ATTR-CM with a 10-year estimated risk of 29.5% (95% CI 7.9-46.0). Cardiac penetrance increased with increasing family members age. Probands diagnosis age (p=0.0096) and artificial intelligence (AI)-ECG prediction (p=0.0091) were promising baseline predictors of time to ATTRv-CM development. CONCLUSIONIn previously undiagnosed G+P-ATTRv family members, the incidence of subsequent CM is high. Predictors for CM development such as probands diagnosis age and AI-determined ECG probability of ATTR-CM require further investigation.

BackgroundGenetic diagnosis has become increasingly important to guide clinical decision making for patients with dilated cardiomyopathy (DCM). Disease-causing (P/LP) missense variants in the gene RBM20 cause a highly penetrant arrhythmogenic dilated cardiomyopathy (DCM), but the role of truncating RBM20 variants (RBM20tvs) is unclear. ObjectiveAssess the contribution of RBM20tvs to DCM. MethodsWe assembled an international cohort of DCM patients with RBM20 variants and used data from the genome-first UK Biobank (UKB) to assess the etiologic fraction, natural history and penetrance of RBM20tvs. ResultsThe etiologic fraction of RBM20tvs in arrhythmogenic DCM was modest (0.53[0.32,0.67], p=7.5x10-5). RBM20tv DCM patients presented to referral centers later in life than RBM20 P/LP DCM patients (53{+/-}10 vs. 34{+/-}18 years, p=4x10-3), and were less likely to have a family history of sudden cardiac arrest (20% vs. 65%, p= 0.046) or cardiomyopathy (20% vs. 78% p=5.4x10-3). There was no significant difference in age- and sex-adjusted incident major heart failure or arrhythmia events between RBM20tv and RBM20 P/LP DCM patients, though sex-adjusted lifetime hazard was reduced in RBM20tv DCM (HR 0.15[0.03,0.66],p=0.009). In UKB, lifetime incidence of cardiomyopathy, heart failure, or major ventricular arrhythmia diagnosis was lower in participants with RBM20tvs than in those with TTNtvs (HR 0.55 [0.36,0.84], p=5.9x10-3). ConclusionsRBM20tvs contribute to arrhythmogenic DCM phenotypes, but confer milder disease severity alone than RBM20 P/LP variants, and reduced lifetime disease penetrance compared to TTNtvs. Their potential for additive interactions with other damaging variants should be considered in DCM patients and families.