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PubMed2025

Epigenetic Regulation in Dilated Cardiomyopathy.

Dilated cardiomyopathy (DCM) is a nonischemic heart muscle disease characterized by impaired contractility, cardiac dilation, and heart failure, with both genetic and nongenetic causes. Emerging evidence highlights epigenetic mechanisms, including deoxyribonucleic acid methylation, histone modifications, chromatin remodeling, and noncoding RNAs, as critical regulators of gene expression in DCM pathogenesis. This article explores familial DCM linked to pathogenic variants in genes like lamin A/C and titin, as well as nongenetic forms such as diabetic and autoimmune DCM. By summarizing recent discoveries, it highlights the epigenetic factors in bridging genetic and environmental influences, offering potential biomarkers and therapeutic targets for improved DCM management.

Humans↗

PubMed2026

Clinical characteristics and prognostic impact of multiple pathogenic variants across the genetic spectrum of arrhythmogenic and dilated cardiomyopathies.

BACKGROUND: Arrhythmogenic and dilated cardiomyopathies (ACM and DCM, respectively) are genetically heterogeneous disorders of the right and/or left ventricles associated with an increased risk of major arrhythmic events (MAE) and end-stage heart failure (ESHF). In arrhythmogenic right ventricular cardiomyopathy (ARVC), the presence of >1 pathogenic or likely pathogenic (P/LP) variant is associated with worse outcomes. Whether this phenomenon occurs for non-desmosomal arrhythmogenic left ventricular cardiomyopathy (ALVC)/DCM genes is unknown. OBJECTIVE: This study aimed to evaluate the impact of single vs multiple P/LP variants on arrhythmic and heart failure outcomes across the ACM/DCM genetic spectrum. METHODS: We retrospectively analyzed 1054 genotype-positive patients with ≥1 P/LP variant in a definitive or strong evidence ARVC- or ALVC/DCM-causative gene. Primary endpoints were MAE (sustained ventricular tachycardia, ventricular fibrillation, aborted cardiac arrest, appropriate implantable cardioverter-defibrillator therapy, and sudden cardiac death) and ESHF (transplant or heart failure death). RESULTS: Of the 1054 patients, 27 (3%) harbored >1 P/LP variants (21 with ≥1 ALVC/DCM gene; 6 with >1 ARVC gene). MAE occurred in 20% of single-variant patients compared with 48% and 50% of those with >1 P/LP variants in ≥1 ALVC/DCM- and >1 ARVC-susceptibility gene(s), respectively. ESHF occurred in 9%, 29%, and 17% of patients, respectively. On adjusted analysis, >1 P/LP variants in ≥1 ALVC/DCM-susceptibility (MAE hazard ratio [HR], 2.46 [1.28-4.72]; P = .01 and ESHF HR, 3.15 [1.35-7.37], P = .01) and >1 ARVC-susceptibility gene(s) (MAE HR, 2.67 [1.28-8.72], P = .03) were independent predictors of the primary endpoints. CONCLUSION: Multiple P/LP variants confer an increased risk of arrhythmic events and heart failure across the ACM/DCM spectrum.

Arrhythmogenic cardiomyopathy↗

PubMed2026

Comparative whole-exome sequencing of ambulatory patients and transplant recipients with idiopathic dilated cardiomyopathy.

BACKGROUND: Idiopathic dilated cardiomyopathy (DCM) is a major cause of advanced heart failure and heart transplantation (HTx), yet the genetic correlates of progression to HTx and transplant-relevant arrhythmic phenotypes remain incompletely defined. We examined the genetics of idiopathic DCM in a Korean population, focusing on HTx/death and arrhythmic outcomes, to identify adverse outcome-linked genotype-phenotype associations. METHODS: Whole-exome sequencing was performed in 202 Korean patients with idiopathic DCM, including 56 HTx recipients and 146 ambulatory patients, and compared the findings with 1093 population-based controls. Genotype-phenotype correlations were analyzed for major clinical outcomes, including HTx, death, arrhythmias, and left ventricular functional recovery. RESULTS: Pathogenic/likely pathogenic variants were identified in 32% of patients (38% in HTx vs 30% in ambulatory patients). TTN was the most frequently affected gene overall (12%), but LMNA variants predominated in HTx recipients (20% vs 4%, p = 0.001). LMNA carriers showed substantially higher odds of HTx/death (OR 14.65, 95% CI 3.32-139.31; FDR p<0.001), and strong association with arrhythmias, including ventricular tachyarrhythmias and atrial fibrillation. Both missense and loss-of-function LMNA variants were associated with adverse outcomes. In contrast, TNNT2 variants were observed exclusively in ambulatory patients and identified a favorable functional-recovery phenotype, with a greater likelihood of LVEF recovery ≥10 percentage points (OR 6.03, 95% CI 1.52-28.71; FDR p = 0.016). CONCLUSIONS: LMNA variants mark a high-risk transplant-trajectory phenotype in Korean idiopathic DCM. Genetic testing may aid early identification and management of candidates for advanced HF therapies, including HTx and durable MCS.

dilated cardiomyopathy↗

PubMed2025

Identification of Biomarkers for Right Ventricular Dysfunction in Idiopathic Dilated Cardiomyopathy Via Urinary Proteomics and Machine Learning.

BACKGROUND: Right ventricular dysfunction (RVD) is a common complication of idiopathic dilated cardiomyopathy linked to poor outcomes. However, reliable noninvasive biomarkers for RVD remain lacking. This study aimed to identify urinary proteomic markers using mass spectrometry and machine learning. METHODS: In this prospective cohort, patients with idiopathic dilated cardiomyopathy were classified by cardiac magnetic resonance imaging into groups with RVD (RV ejection fraction <45%) and without RVD groups. Baseline urine samples were profiled by data-independent acquisition mass spectrometry. Differentially expressed proteins were identified and selected by least absolute shrinkage and selection operator regression to build a diagnostic model, developed in a training set, and validated in a test set. The primary end point was a composite of cardiovascular death, heart failure rehospitalization, left ventricular assist device implantation, or heart transplantation. RESULTS: The study enrolled 147 patients with idiopathic dilated cardiomyopathy (64 with RVD, 83 without), with a median follow-up of 19.3 months. Of 3579 quantified urinary proteins, 46 were differentially expressed between groups. A 3-protein panel (RARRES1 [retinoic acid receptor responder protein 1], MVB12B [multivesicular body subunit 12B], GSK3A [glycogen synthase kinase 3 alpha]) was identified and showed excellent diagnostic accuracy (training area under the curve 0.946; validation area under the curve0.935), outperforming both NT-proBNP (N-terminal pro-brain natriuretic peptide) and tricuspid annular plane systolic excursion. The risk score derived from this panel effectively stratified patients, with the high-risk group exhibiting significantly worse outcomes than the low-risk group (hazard ratio, 3.24 [95% CI, 1.56-6.71], P=0.002). CONCLUSIONS: The urinary proteomic panel developed in this study demonstrates diagnostic and prognostic potential for identifying RVD in idiopathic dilated cardiomyopathy, providing a promising noninvasive tool for precise detection and clinical risk stratification.

Humans↗

PubMed2026

Dysregulated Ribonucleoprotein Granules Impair Mitochondrial Function in RBM20-Related Dilated Cardiomyopathy.

BACKGROUND: Pathogenic variants in RBM20 cause severe dilated cardiomyopathy. Loss-of-function variants disrupt splicing; neomorphic gain-of-function (GoF) variants also mislocalize RBM20 to cytoplasmic ribonucleoprotein granules and are associated with more aggressive disease. The mechanism by which RBM20 mislocalization drives cardiac dysfunction remains unknown. METHODS: We investigated the effects of Rbm20 GoF and loss-of-function (LoF) variants using proteomic profiling, protein solubility assays, mitochondrial respiration and calcium flux analyses, and ultrastructural imaging in mouse models. Human induced pluripotent stem cell-derived cardioids were used to validate variant-specific phenotypes. RESULTS: Rbm20 GoF, but not LoF, variants caused posttranscriptional downregulation of soluble mitochondrial proteins, including the calcium efflux regulator TMEM65 (transmembrane protein 65), and reduced solubility of mitochondrial membrane proteins. Electron microscopy revealed enlarged mitochondria with cristae disorganization. Functional assays confirmed impaired oxidative phosphorylation, reduced mitochondrial membrane potential, and abnormal calcium handling in Rbm20 GoF models. Human cardioids reproduced these findings, demonstrating that cytoplasmic mislocalization, rather than splicing deficiency, drives mitochondrial dysfunction. CONCLUSIONS: Cytoplasmic mislocalization of RBM20 disrupts mitochondrial function by reducing mitochondrial protein abundance, leading to oxidative phosphorylation failure and abnormal mitochondrial calcium handling. This mechanism distinguishes RBM20 GoF from LoF variants and may explain the more severe heart failure phenotype observed in patients with RBM20 GoF variants. These insights advance the mechanistic understanding of RBM20-related cardiomyopathy and identify mitochondrial mRNA/protein regulation as a key node in cardiac energetics.

cardiomyopathy, dilated↗

PubMed2026

The bidirectional genetic causality between immunocyte phenotypes and dilated cardiomyopathy: A bidirectional Mendelian randomization study.

The association between immunocyte phenotypes and dilated cardiomyopathy (DCM) has been explored, however the exact pathogenesis of the relationship between immune cells and DCM is unclear. This bidirectional two-sample Mendelian randomization (MR) research aims to further validate the causal link between 731 immunocyte phenotypes and DCM. Summary statistics from a genome-wide association study data of individuals with European ancestry were utilized, including 1444 DCM cases and 353,937 controls, as well as 3757 European adults for the 731 immunocyte phenotypes. Causal effects were estimated using inverse variance weighted, MR-Egger regression, weight median estimator, weighted mode, and simple mode. Sensitivity analysis was conducted to confirm data robustness and feasibility. Based on the inverse variance weighted findings, 14 immunocyte phenotypes were risk factors for DCM (P < .05, odds ratio [OR] > 1), while 15 immunocyte phenotypes exhibited a protective effect on DCM (P < .05, OR < 1). The results of reverse MR analysis suggested evidence that DCM occurrence might elevate the levels of 17 immunocyte phenotypes (P < .05, OR > 1) and decrease the levels of 9 immunocyte phenotypes (P < .05, OR < 1). Our research indicated that CD28 on secreting regulatory T cell could mitigate the occurrence of DCM, and reciprocally, the progression of DCM could reduce the level of CD28 on secreting regulatory T cell. This study confirmed the bidirectional genetic predictive relationship between immunocyte phenotypes and DCM, underscoring the complex interplay between DCM and the immune system.

Cardiomyopathy, Dilated↗

PubMed2026

Novel association of NAV3 with dilated cardiomyopathy and its role in cardiac fibrosis.

A genome-wide association study (GWAS) identified neuron navigator 3 (NAV3) as a potential genetic determinant of myocardial recovery in dilated cardiomyopathy (DCM). This study aimed to understand its functional role in cardiac pathophysiology by leveraging omics approaches. Single-cell RNA-seq transcriptomic data from previously published adult human hearts indicate that NAV3 expression is highest in cardiac fibroblasts, suggesting its functional role in these cells. In vitro, stimulation of primary human ventricular cardiac fibroblasts with transforming growth factor β1 (TGF-β1) induced NAV3 expression in a dose and time-dependent manner. Small-interfering-RNA-mediated knockdown of NAV3 significantly attenuated TGF-β1-induced fibroblast activation, reducing the expression of α-smooth muscle actin (α-SMA), collagens, and fibronectin. RNA sequencing of NAV3-silenced fibroblasts, confirmed by Western blot, revealed upregulation of cell cycle regulators and downregulation of profibrotic markers, suggesting that NAV3 facilitates TGF-β1-induced cell cycle arrest and fibroblast-to-myofibroblast transition. Notably, NAV3 silencing did not alter canonical SMAD2/3 phosphorylation, implying a role for NAV3 in modulating fibrotic signaling through other pathways. Our findings provide functional and mechanistic insights into NAV3's novel role in cardiac fibrosis, showing that reduced NAV3 expression attenuates TGF-β1-mediated fibroblast activation by regulating cell cycle signaling. These results support further investigation of NAV3 as a potential modulator of cardiac fibrosis and myocardial recovery in DCM.NEW & NOTEWORTHY This study uncovers a previously unrecognized role for NAV3 in TGF-β1-driven cardiac fibroblast activation. We show that NAV3 facilitates profibrotic remodeling through noncanonical signaling and cell cycle arrest, independently of SMAD2/3. These findings position NAV3 as a novel regulator of fibroblast phenotype and a potential modulator of cardiac fibrosis.

Humans↗

PubMed2026

Care Models for the Genetic Evaluation of Dilated Cardiomyopathy at Sites of the DCM Consortium.

BACKGROUND: Clinical genetic evaluation for patients with dilated cardiomyopathy (DCM) is minimally implemented, and models of care are not well defined. To understand current genetic care for DCM, a systematic needs assessment was conducted. METHODS: Principal investigators of the DCM Consortium convened at the Summer Scientific Symposium in July 2025. An electronic needs assessment was conducted among the 24 principal investigators in advance to define current care models by evaluating which genetic evaluation components recommended by the Heart Failure Society of America were conducted, by whom, and the time required for each component. Descriptive statistics were generated to characterize model features. Focus group discussions explored barriers and facilitators to implementing genetic services. RESULTS: Four care models emerged from the principal investigator responses: model 1: Traditional-Synchronous (25%, n=6, requiring the most time per patient); model 2: Traditional-Asynchronous (33%, n=8); model 3: Externally Sourced (17%, n=4); and model 4: Physician/Advanced Practice Provider Conducted (25%, n=6, requiring the least time per patient). All models used genetic testing, whereas other components were implemented variably or not at all. Models 1 (15.7±4.1) and 2 (15.4±3.0) were rated more acceptable than model 4 (9.8±2.9; model 1 versus model 4; P=0.027; model 2 versus model 4; P=0.023). Notably, 88% of principal investigators used genetic information for treatment decisions, including implantable cardioverter defibrillator placement (83%; n=20) and cardiac transplantation (63%; n=15). Major facilitator themes from focus group discussions included having a genetic counselor as part of the heart failure team and developing authoritative standards directing provision of DCM genetic services. Barrier themes included operational challenges, limited personnel, clinician under-recognition, need for new service delivery models, and billing/reimbursement. CONCLUSIONS: DCM genetic care models and components were highly variable across the 24 sites of the DCM Consortium, although all sites discussed similar factors that enable or hinder the implementation of genetic services for DCM. Understanding the basis of practice model variability may provide insight to yield more scalable care approaches.

cardiomyopathy, dilated↗

PubMed2026

An Updated Evidence Assessment of the Genetic Causes of Dilated Cardiomyopathy.

BACKGROUND: Evidence 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 evaluation, the DCM gene curation expert panel reconvened in 2024-2025 to conduct a reassessment of genes in DCM. METHODS: The Clinical Genome Resource semiquantitative clinical validity classification framework was applied with specifications to DCM to classify genes into categories on the basis of 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. RESULTS: Sixty-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: 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 reevaluated genes from 2019-2020 had clinically significant changes in classification. Except for JPH2, for which curation was modified to separate autosomal dominant and AR MOI curations, clinically significant changes involved upgrades from low- to high-evidence categories (PLEKHM2, PRDM16, TBX20, TNNI3K), demonstrating the robustness of the Clinical Genome Resource gene curation process over time. An additional 29 gene-disease-MOI curations were classified as Limited, including 6 newly evaluated genes and 1 new MOI for a previously evaluated gene, MYBPC3-AR; 4 were classified as No Known Disease Relationship, and remained Disputed. Four previously evaluated genes were curated for both AD and AR MOIs: JPH2 (AD-Strong, AR-Limited), LDB3 (AD-Limited, AR-Strong), MYBPC3 (AD-Limited, AR-Limited), and TNNI3 (AD- and AR- Strong). CONCLUSIONS: With 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 5 years ago. The results of this evidence-based evaluation process inform clinical interpretation of genetic information in the care of DCM patients and families.

dilated cardiomyopathy↗

PubMed2026

A Common CD36 Variant and the Genetic Landscape of Dilated Cardiomyopathy in Individuals of African Ancestry.

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.

Journal Article↗

PubMed2026

Generation of two induced pluripotent stem cell lines from dilated cardiomyopathy patients with TTN mutations.

Titin (TTN) encodes the largest protein in the human body and is essential for sarcomere assembly and muscle mechanosensation. Truncating TTN mutations are a leading cause of dilated cardiomyopathy (DCM). Here, we generated two induced pluripotent stem cell (iPSC) lines from female DCM patients, each carrying a heterozygous nonsense point mutation that produces a truncated titin protein. Both lines were reprogrammed from peripheral blood mononuclear cells (PBMCs) and characterized for expression of undifferentiated human iPSC state markers, tri-lineage differentiation capacity, and genomic integrity by copy-number analysis. These lines provide a patient-derived platform for investigating the mechanobiological basis of titin-truncation DCM in vitro.

Humans↗

PubMed2026

Care Models for the Genetic Evaluation of Dilated Cardiomyopathy at Sites of the DCM Consortium.

BACKGROUND: Clinical genetic evaluation for patients with dilated cardiomyopathy (DCM) is minimally implemented and models of care are not defined. To understand current genetics care for DCM, a systematic needs assessment was conducted. METHODS: Principal Investigators (PIs) of the DCM Consortium convened at the Summer Scientific Symposium in July 2025. An electronic needs assessment was collected from the 24 PIs in advance to define current care models by evaluating which Heart Failure Society of America-recommended genetic evaluation components are conducted, by whom, and time required. Descriptive statistics were generated to characterize model features. Focus group discussions explored barriers and facilitators to implementing genetic services. RESULTS: Four care models emerged from the PI responses: 1 - Traditional-Synchronous (25%, n=6, requiring the most time per patient), 2 - Traditional-Asynchronous (33%, n=8), 3 - Externally Sourced (17%, n=4), and 4 - Physician/Advanced Practice Provider Conducted (25%, n=6, requiring the least time per patient). All models used genetic testing, whereas other components were implemented variably or not at all. Models 1 (15.7±4.1) and 2 (15.4±3.0) were rated more acceptable than Model 4 (9.8±2.9; 1 vs 4: p=0.027; 2 vs 4, p=0.023). Notably, 88% of PIs used genetic information for treatment decisions, including ICD placement (83%; n=20) or cardiac transplant (63%; n=15). Major facilitator themes from focus group discussions included having a genetic counselor on the HF team and developing authoritative standards directing provision of DCM genetic services. Barrier themes included operational challenges, limited personnel, clinician under-recognition, need for new service delivery models, and billing/reimbursement. CONCLUSIONS: DCM genetic care models and components were highly variable across the 24 sites of the DCM Consortium, even though all sites discussed similar factors that enable or hinder implementing genetic services for DCM. Understanding the basis of practice model variability may provide insight to yield more scalable care approaches.

clinical genetics↗

PubMed2026

Whole-genome sequencing identifies a c.1282C > T missense variant in Taurine Transporter (TauT) associated with taurine-mediated dilated cardiomyopathy in a family of domestic shorthair cats.

Taurine is a cytoprotectant amino acid critical for a variety of cellular functions, including cell volume and intracellular calcium regulation, bile salt formation, free radical protection, and mitochondrial biogenesis. In most mammals, taurine is synthesized via methionine transsulfuration; albeit, in cats, taurine biosynthesis is blunted due to low enzymatic activity of their encoded cysteine sulfonic acid decarboxylase and, therefore, is an essential amino acid in the species. Taurine deficiency in cats results in retinopathy, coagulopathy, growth retardation, impaired immunological function, and most notably dilated cardiomyopathy (DCM). A three-year-old domestic shorthair cat was evaluated for vomiting, anorexia, and lethargy. Severe dilated cardiomyopathy and taurine deficiency were identified, despite eating a commercial, nutritionally balanced, diet with adequate taurine concentrations. A whole-genome association study (WGAS), under the assumptions of an incomplete dominance mode of inheritance (MOI), was performed on this case and two related cats with mild taurine and echocardiographic abnormalities (i.e., queen and littermate) compared to 18 previously whole-genome sequenced echocardiographically-normal geriatric controls (>10 years-of-age; n = 21). A 'MODERATE' c.1282C > T; p.Arg428Trp variant harbored in Solute Carrier Family 6 Member 6/Taurine Transporter (SLC6A6/TauT) was identified. The variant segregated to the postulated MOI and was not observed in any of the control or in an expanded population of cats (n = 422). Functional analyses involving wildtype and mutant SLC6A6 overexpression in HEK293-derived cells revealed marked reduction in cellular taurine uptake and decreased plasma membrane expression in those harboring the c.1282C > T variant. This represents the first-ever reported genetic variant explaining taurine deficiency in any domestic animal species.

Dilation↗

PubMed2025

Cardiac CT fractal analysis of LV noncompaction and common cardiomyopathies.

BACKGROUND: Left ventricular noncompaction (LVNC), or hypertrabeculation, is a myocardial condition that remains challenging to diagnose and differentiate from other cardiomyopathies. This study evaluated the ability of cardiac CT to differentiate between LVNC, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and controls using fractal analysis of LV trabeculae. METHODS: Subjects with LVNC, HCM, DCM, as well as controls, who underwent coronary CT angiography were included. LV trabecular structure was quantified using fractal analysis on a stack of 15 short-axis CT images. For each subject, maximum (FDmax) and average (FDglobal) fractal dimensions were reported. A subset of subjects also had clinically acquired cardiac MRI (CMR) exams for comparison. One-way ANOVA, Pearson correlation, and Bland-Altman analysis were used for statistical analysis. RESULTS: The study included 313 subjects (median age: 58.8 [48.1-68.0] years, 153 male) categorized into Control (89), LVNC (46), HCM (106), and DCM (72) cohorts. FDmax was significantly higher in LVNC (1.379 ± 0.047) than in Control (1.305 ± 0.033), HCM (1.321 ± 0.040), and DCM (1.344 ± 0.054) cohorts; all p < 0.001. Similarly, FDglobal was significantly higher in LVNC (1.279 ± 0.041) than in the other cohorts; all p < 0.05. In a subset of 132 subjects with both CT and CMR exams, fractal dimensions from the two modalities were strongly correlated (r = 0.63, p < 0.0001), with CT-derived values being higher (1.337 ± 0.049 vs. 1.262 ± 0.045, p < 0.0001). CONCLUSIONS: CT-derived fractal dimensions of LV trabecular structure were significantly higher in LVNC compared to control subjects, HCM, and DCM. CT-derived fractal dimensions strongly correlated with, but were higher than, those from cardiac MRI in the same subjects.

Humans↗

PubMed2025

Genome sequencing reveals the impact of pseudoexons in rare genetic disease.

PURPOSE: Advancements in sequencing technologies have significantly improved clinical genetic testing; yet, the diagnostic yield remains around 30% to 40%. Emerging technologies are now being deployed to address the remaining diagnostic gap. METHODS: We tested whether short-read genome sequencing could increase the diagnostic yield in individuals enrolled into the UCI-GREGoR research study, who had suspected Mendelian conditions and prior inconclusive testing. Two other collaborative research cohorts, focused on aortopathy and dilated cardiomyopathy, consisted of individuals who were undiagnosed but had not undergone harmonized prior testing. RESULTS: We sequenced 353 families (754 participants) and found a molecular diagnosis in 54 (15.3%) of them. Of these diagnoses, 55.5% were previously missed because the causative variants were in regions not originally interrogated. In 5 cases, they were deep intronic variants, all of which led to abnormal splicing and pseudoexons, as directly shown by RNA sequencing. All 5 of these variants had inconclusive spliceAI scores. In 26% of newly diagnosed cases, the causal variant could have been detected by exome sequencing reanalysis. CONCLUSION: Genome sequencing can overcome limitations of clinical genetic testing, such as the inability to call intronic variants. Our findings highlight pseudoexons as a common mechanism via which deep intronic variants cause Mendelian disease.

Humans↗

PubMed2026

Common Molecular Mechanisms and Candidate Drug Targets in Type 2 Diabetes Mellitus and Atherosclerotic Cardiovascular Disease.

This study examined the mechanisms underlying the comorbidity between type 2 diabetes mellitus (T2DM) and atherosclerotic cardiovascular disease (ASCVD), while identifying potential therapeutic targets. Common differentially expressed genes (C-DEGs) between T2DM and ASCVD were extracted from the GSE78721 and GSE12288 datasets. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, protein-protein interaction (PPI) network construction, hub gene identification, and Drug-Gene Interaction Database (DGIdb) analysis were conducted. The association between hub C-DEGs and immune-infiltrating cells was analyzed using the CIBERSORT method. Expression levels of hub C-DEGs were quantified through qRT-PCR and Western blot analyses. A total of 32 C-DEGs were identified, comprising 20 upregulated and 12 downregulated genes. C-DEGs were predominantly enriched in key pathways, including viral myocarditis, arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, and dilated cardiomyopathy. PPI analysis revealed 29 nodes and 39 edges, leading to the identification of eight hub C-DEGs (HSP90B1, PLAU, SLPI, TOP3A, NCF4, PRF1, TUBA1C, and CS) across both datasets. Furthermore, hub C-DEGs (TOP3A, SLPI, NCF4, PRF1, and PLAU) demonstrated significant correlations with immune-infiltrating cell levels. Drugs specifically targeting these hub C-DEGs present promising candidates for the treatment of T2DM and ASCVD. Additionally, the expression of hub C-DEGs at both mRNA and protein levels was validated in patients with T2DM and ASCVD. An integrated bioinformatics analysis facilitated the screening of candidate therapeutic targets, mechanisms, and drugs for T2DM and ASCVD, offering new insights into molecular therapies for these conditions.

Diabetes Mellitus, Type 2↗

PubMed1975

Pathologic anatomy of the cardiomyopathies. Idiopathic dilated and hypertrophic types, infiltrative types, and endomyocardial disease with and without eosinophilia.

This presentation summarizes necropsy observations in patients with three types of cardiomyopathy: idiopathic, infiltrative, and endomyocardial disease. The idiopathic variety is subdivided into two types depending on the size of the ventricular cavity. In the dilated ventricular type the left ventricular wall is frequently less than 1.5 cm. thick, intracardiac thrombi are common, the atrioventricular valve rings usually are mildly dilated, and focal myocardial and endocardial scars are common. In the nondilated type (hypertrophic cardiomyopathy), the ventricular septum is usually thicker than the left ventricular free wall, which also is thick (greater than 1.5 cm.). When the septum is similar in thickness to the left ventricular free wall (symmetric), left ventricular outflow obstruction does not occur. When the septum is thicker than the left ventricular free wall (asymmetric), left or right ventricular outflow obstruction may or may not be present. The orientation of myocardial fibers one to another in the ventricular septum in the nondilated (hypertrophic) type is abnormal, whereas it is normal in the dilated ventricular type. Intracardiac thrombi are rare and atrioventricular valve rings are never dilated in the nondilated type of idiopathic cardiomegaly. The infiltrative types of cardiomyopathies include iron, calcium, lipids, mucopolysaccharides, granulomas, amyloid, and neoplasms. The first four usually are located within myocardial cells and the latter three, between myocardial cells. It is probable that all these myocardial infiltrates are capable of producing cardiac dysfunction, primarily on a restrictive basis. Endomyocardial disease may or may not be associated with eosinophilia. When the latter occurs, the eosinophils are structurally normal. Death is related to congestive cardiac failure. This category is actuality also in idiopathic.

Adolescent↗

PubMed2026

Functional Validation of a Novel Homozygous TTN Splice-Site Variant Reveals Aberrant Splicing in Hypertrophic Cardiomyopathy.

The TTN gene encodes a crucial structural protein within cardiac sarcomeres, and its variants may contribute to hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy; however, phenotype and genotype are different. Whole-exome sequencing (WES) was conducted on a Chinese proband diagnosed with HCM. In silico splicing prediction tools and minigene assays were employed to investigate the impact of the identified variant on mRNA splicing. A literature review was performed to retrieve and analyze previously reported splicing variants in the TTN gene associated with HCM. A 42-year-old male proband presented with nonobstructive HCM and paroxysmal atrial arrhythmias. A novel homozygous TTN variant was found, predicted to cause a 14-base pair deletion at a splice acceptor site. Two asymptomatic offspring were found to carry the heterozygous variant. Based on variant interpretation guidelines, the variant met the PM2_supporting criterion and was classified as a variant of uncertain significance (VUS). The predicted aberrant splicing effect was subsequently confirmed by the minigene splicing assay, demonstrating altered pre-mRNA splicing leading to an in-frame insertion/deletion (p.Arg32498_Glu32504delinsGln). Functional verification confirmed that this mutation conforms to the PM4 criterion, suggesting that it can be reclassified as a tepid VUS (scoring 3 points). The functional result might provide pathogenic evidence. We also reviewed 28 previously reported splicing variants in TTN associated with HCM. Of these, 57.1% (16/28) localized to the I-band region, whereas 21.4% (6/28) were situated in the A-band domain of titin. Notably, 21.4% (6/28) co-occurred with pathogenic variants in other sarcomeric genes (MYH7 or MYBPC3), correlating with more severe clinical phenotypes. Reclassification and reinterpretation of the variants revealed that none met the level of likely pathogenic or higher. The present case contributes a homozygous splice-site variant with experimentally confirmed aberrant splicing and an in-frame protein alteration in titin. The focus of this report is the Mendelian genetic basis of the proband's cardiomyopathy phenotype, and our data provide additional case-level and functional evidence for a possible role of specific TTN splicing defects in HCM.

Humans↗