A genetic association study of circulating coagulation factor VIII and von Willebrand factor levels.

ABSTRACT: Coagulation factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are critical to coagulation and platelet aggregation. We leveraged whole-genome sequence data from the Trans-Omics for Precision Medicine (TOPMed) program along with TOPMed-based imputation of genotypes in additional samples to identify genetic associations with circulating FVIII and VWF levels in a single-variant meta-analysis, including up to 45 289 participants. Gene-based aggregate tests were implemented in TOPMed. We identified 3 candidate causal genes and tested their functional effect on FVIII release from human liver endothelial cells (HLECs) and VWF release from human umbilical vein endothelial cells. Mendelian randomization was also performed to provide evidence for causal associations of FVIII and VWF with thrombotic outcomes. We identified associations (P < 5 × 10-9) at 7 new loci for FVIII (ST3GAL4, CLEC4M, B3GNT2, ASGR1, F12, KNG1, and TREM1/NCR2) and 1 for VWF (B3GNT2). VWF, ABO, and STAB2 were associated with FVIII and VWF in gene-based analyses. Multiphenotype analysis of FVIII and VWF identified another 3 new loci, including PDIA3. Silencing of B3GNT2 and the previously reported CD36 gene decreased release of FVIII by HLECs, whereas silencing of B3GNT2, CD36, and PDIA3 decreased release of VWF by HVECs. Mendelian randomization supports causal association of higher FVIII and VWF with increased risk of thrombotic outcomes. Seven new loci were identified for FVIII and 1 for VWF, with evidence supporting causal associations of FVIII and VWF with thrombotic outcomes. B3GNT2, CD36, and PDIA3 modulate the release of FVIII and/or VWF in vitro.

Redefining tissue specificity of genetic regulation of gene expression in the presence of allelic heterogeneity.

Uncovering the functional impact of genetic variation on gene expression is important in understanding tissue biology and the pathogenesis of complex traits. Despite large efforts to map expression quantitative trait loci (eQTLs) across many human tissues, our ability to translate those findings to understanding human disease has been incomplete, and the majority of disease loci are not explained by association with expression of a target gene. Cell-type specificity and the presence of multiple independent causal variants for many eQTLs are potential confounders contributing to the apparent discrepancy with disease loci. In this study, we investigate the tissue specificity of genetic effects on gene expression and the overlap with disease loci while considering the presence of multiple causal variants within and across tissues. We find evidence of pervasive tissue specificity of eQTLs, often masked by linkage disequilibrium that misleads traditional meta-analytic approaches. We propose CAFEH (colocalization and fine-mapping in the presence of allelic heterogeneity), a Bayesian method that integrates genetic association data across multiple traits, incorporating linkage disequilibrium to identify causal variants. CAFEH outperforms previous approaches in colocalization and fine-mapping. Using CAFEH, we show that genes with highly tissue-specific genetic effects are under greater selection, enriched in differentiation and developmental processes, and more likely to be involved in human disease. Last, we demonstrate that CAFEH can efficiently leverage the widespread allelic heterogeneity in genetic regulation of gene expression to prioritize the target tissue in genome-wide association complex trait loci, thereby improving our ability to interpret complex trait genetics.

Peroxisome Proliferator-Activated Receptor Gamma Regulates Interleukin-6-Induced Lipoprotein (a) Gene Expression in Human HepG2 Cells.

Lipoprotein(a) [Lp(a)] is a risk factor for coronary disease. Although levels are primarily genetically determined, data from patients with inflammatory diseases indicate that the inflammatory milieu is associated with increased Lp(a) levels. Lp(a) is synthesized in the liver and the LPA gene promoter contains an interleukin-6 (IL-6) responsive binding site, but the regulatory steps linking inflammation with hepatic Lp(a) synthesis are not well clarified. We explored the interplay between IL-6, peroxisome proliferator-activated receptor gamma (PPARγ), and Lp(a) synthesis in HepG2 cells. Through genetic mapping, a regulatory variant within the LPA promoter overlapping with a PPARγ binding site was identified. In in vitro experiments, IL-6-mediated LPA gene transcription was heightened with PPARγ knock-down and suppressed with pioglitazone, a PPARγ agonist. These results demonstrate an important role of PPARγ as a negative regulator of IL-6 induced hepatic Lp(a) production and may represent a new therapeutic target for patients with inflammatory conditions characterized by elevated Lp(a).

Dyslipidemia.

Dyslipidemia is an important risk factor for coronary artery disease and stroke. All persons with dyslipidemia should be advised to focus on lifestyle interventions, including regular aerobic exercise, a healthy diet, maintenance of a healthy weight, and abstinence from smoking. In addition to lifestyle interventions, lipid-lowering therapy should be considered for persons at moderate to high risk for atherosclerotic cardiovascular disease based on validated risk equations. Statin therapy is the first-line medical treatment for dyslipidemia due to its effectiveness and favorable adverse effect profile, but newer treatments provide additional tools for clinicians to effectively treat dyslipidemia.

CCRL2 affects the sensitivity of myelodysplastic syndrome and secondary acute myeloid leukemia cells to azacitidine.

Better understanding of the biology of resistance to DNA methyltransferase (DNMT) inhibitors is required to identify therapies that can improve their efficacy for patients with high-risk myelodysplastic syndrome (MDS). CCRL2 is an atypical chemokine receptor that is upregulated in CD34+ cells from MDS patients and induces proliferation of MDS and secondary acute myeloid leukemia (sAML) cells. In this study, we evaluated any role that CCRL2 may have in the regulation of pathways associated with poor response or resistance to DNMT inhibitors. We found that CCRL2 knockdown in TF-1 cells downregulated DNA methylation and PRC2 activity pathways and increased DNMT suppression by azacitidine in MDS/sAML cell lines (MDS92, MDS-L and TF-1). Consistently, CCRL2 deletion increased the sensitivity of these cells to azacitidine in vitro and the efficacy of azacitidine in an MDS-L xenograft model. Furthermore, CCRL2 overexpression in MDS-L and TF-1 cells decreased their sensitivity to azacitidine. Finally, CCRL2 levels were higher in CD34+ cells from MDS and MDS/myeloproliferative neoplasm patients with poor response to DNMT inhibitors. In conclusion, we demonstrated that CCRL2 modulates epigenetic regulatory pathways, particularly DNMT levels, and affects the sensitivity of MDS/sAML cells to azacitidine. These results support CCRL2 targeting as having therapeutic potential in MDS/sAML.

Linear and Nonlinear Mendelian Randomization Analyses of the Association Between Diastolic Blood Pressure and Cardiovascular Events: The J-Curve Revisited.

BACKGROUND: Recent clinical guidelines support intensive blood pressure treatment targets. However, observational data suggest that excessive diastolic blood pressure (DBP) lowering might increase the risk of myocardial infarction (MI), reflecting a J- or U-shaped relationship. METHODS: We analyzed 47 407 participants from 5 cohorts (median age, 60 years). First, to corroborate previous observational analyses, we used traditional statistical methods to test the shape of association between DBP and cardiovascular disease (CVD). Second, we created polygenic risk scores of DBP and systolic blood pressure and generated linear Mendelian randomization (MR) estimates for the effect of DBP on CVD. Third, using novel nonlinear MR approaches, we evaluated for nonlinearity in the genetic relationship between DBP and CVD events. Comprehensive MR interrogation of DBP required us to also model systolic blood pressure, given that the 2 are strongly correlated. RESULTS: Traditional observational analysis of our cohorts suggested a J-shaped association between DBP and MI. By contrast, linear MR analyses demonstrated an adverse effect of increasing DBP increments on CVD outcomes, including MI (MI hazard ratio, 1.07 per unit mm Hg increase in DBP; P<0.001). Furthermore, nonlinear MR analyses found no evidence for a J-shaped relationship; instead confirming that MI risk decreases consistently per unit decrease in DBP, even among individuals with low values of baseline DBP. CONCLUSIONS: In this analysis of the genetic effect of DBP, we found no evidence for a nonlinear J- or U-shaped relationship between DBP and adverse CVD outcomes; including MI.

Fecal Colonization With Extended-spectrum Beta-lactamase-Producing Enterobacteriaceae and Risk Factors Among Healthy Individuals: A Systematic Review and Metaanalysis.

BACKGROUND: Gut colonization is a risk factor for infections with extended-spectrum beta-lactamase (ESBL)-producing organisms. We aimed to determine the ESBL class A reservoir among healthy individuals. METHODS: We searched PubMed and EMBASE (through 10 July 2015) looking for studies that contained data for fecal colonization with ESBL class A bacteria among healthy individuals for each World Health Organization-defined region. Distribution of isolates among cefotaximase (CTX-M), sulfhydryl variable, and temoneira enzymes and data on previous antibiotic use, international travel, previous hospitalization, and animal contacts were extracted. RESULTS: Sixty-six of 17 479 studies on 28 909 healthy individuals were included. The pooled prevalence of ESBL class A colonization was 14% (95% confidence interval [CI], 9, 20), with an increasing trend of 5.38% annually (P = .003). The pooled prevalence was higher in Asia and Africa (ranging from 46%, 95% CI, 29, 63 to 15%, 95% CI, 4, 31) and lower but still significant in central (3%, 95% CI, 1, 5), northern (4%, 95% CI, 2, 6), and southern Europe (6%, 95% CI, 1, 12) and the Americas (2%, 95% CI, 0, 5). CTX-Ms were the prevalent ESBL enzyme (69%). Antibiotic use for the prior 4 or 12 months was associated with a high colonization risk (risk ratio [RR] = 1.63; 95% CI, 1.19, 2.24 and RR = 1.58; 95% CI, 1.16, 2.16, respectively). International travel was also correlated with ESBL colonization [(RR = 4.06, (95% CI, 1.33, 12.41)]. CONCLUSIONS: The ESBL colonization rate among healthy individuals is significant worldwide. This should be taken into consideration in infection control and antibiotic management decisions.

Fungal-bacterial interactions and their relevance in health.

Cross-kingdom interactions between bacteria and fungi are a common occurrence in the environment. Recent studies have identified various types of interactions that either can take the form of a synergistic relationship or can result in an antagonistic interplay with the subsequent destruction or inhibition of growth of bacteria, fungi or both. This cross-kingdom communication is of particular significance in human health and disease, as bacteria and fungi commonly colonize various human surfaces and their interactions can at times alter the outcome of invasive infections. Moreover, mixed infections from both bacteria and fungi are relatively common among critically ill patients and individuals with weak immune responses. The purpose of this review is to summarize our knowledge on the type of interactions between bacteria and fungi and their relevance in human infections.

Molecular and nonmolecular diagnostic methods for invasive fungal infections.

Invasive fungal infections constitute a serious threat to an ever-growing population of immunocompromised individuals and other individuals at risk. Traditional diagnostic methods, such as histopathology and culture, which are still considered the gold standards, have low sensitivity, which underscores the need for the development of new means of detecting fungal infectious agents. Indeed, novel serologic and molecular techniques have been developed and are currently under clinical evaluation. Tests like the galactomannan antigen test for aspergillosis and the ß-glucan test for invasive Candida spp. and molds, as well as other antigen and antibody tests, for Cryptococcus spp., Pneumocystis spp., and dimorphic fungi, have already been established as important diagnostic approaches and are implemented in routine clinical practice. On the other hand, PCR and other molecular approaches, such as matrix-assisted laser desorption ionization (MALDI) and fluorescence in situ hybridization (FISH), have proved promising in clinical trials but still need to undergo standardization before their clinical use can become widespread. The purpose of this review is to highlight the different diagnostic approaches that are currently utilized or under development for invasive fungal infections and to identify their performance characteristics and the challenges associated with their use.

A multi-host approach for the systematic analysis of virulence factors in Cryptococcus neoformans.

A multi-host approach was followed to screen a library of 1201 signature-tagged deletion strains of Cryptococcus neoformans mutants to identify previously unknown virulence factors. The primary screen was performed using a Caenorhabditis elegans-C. neoformans infection assay. The hits among these strains were reconfirmed as less virulent than the wild type in the insect Galleria mellonella-C. neoformans infection assay. After this 2-stage screen, and to prioritize hits, we performed serial evaluations of the selected strains, using the C. elegans model. All hit strains identified through these studies were validated in a murine model of systemic cryptococcosis. Twelve strains were identified through a stepwise screening assay. Among them, 4 (CSN1201, SRE1, RDI1, and YLR243W) were previously discovered, providing proof of principle for this approach, while the role of the remaining 8 genes (CKS101, CNC5600, YOL003C, CND1850, MLH3, HAP502, MSL5, and CNA2580) were not previously described in cryptococcal virulence. The multi-host approach is an efficient method of studying the pathogenesis of C. neoformans. We used diverse model hosts, C. elegans, G. mellonella, and mice, with physiological differences and identified 12 genes associated with mammalian infection. Our approach may be suitable for large pathogenesis screens.

Characteristics, Clinical Relevance, and the Role of Echinocandins in Fungal-Bacterial Interactions.

Fungal-bacterial interactions are common in the environment. The interactions between invasive fungi (eg, Candida species and Aspergillus species) and pathogenic bacteria can be particularly significant in the outcome of human infections. Study of these interactions in vivo using murine or invertebrate models, such as Caenorhabditis elegans or Galleria mellonella, has been very helpful in increasing our understanding of the pathogenesis of mixed infections and in identifying ways to use this between-kingdom interplay to our advantage. Based on their effect against fungal biofilms and their immunomodulatory properties, the newer class of antifungal agents, known as echinocandins, has the potential to be useful in polymicrobial infections and in high-risk complex infections such as ventilator-associated pneumonia or sepsis where colonization by fungi can lead to worse outcomes.

Galactomannan and Polymerase Chain Reaction-Based Screening for Invasive Aspergillosis Among High-Risk Hematology Patients: A Diagnostic Meta-analysis.

BACKGROUND: Screening of high-risk patients for invasive aspergillosis (IA) has the potential to decrease the use of empiric antifungal agents. However, the performance of different screening methods has not been studied. METHODS: We performed a meta-analysis of published studies to assess the diagnostic performance of galactomannan (GM) and polymerase chain reaction (PCR) as weekly screening tests in high-risk populations. The sensitivity and specificity of 6 approaches combining GM and PCR were estimated using the bivariate model. RESULTS: Thirteen studies with 1670 patients met our inclusion criteria. Single positive test results had modest sensitivity and specificity for screening (respectively, 92% and 90% for GM; 84% and 76% for PCR). The screening approach with the highest sensitivity was the one that used at least 1 GM- or PCR-positive result to define a positive episode, achieving a sensitivity of 99%, significantly higher than any single test (P = .0018 compared with GM and P < .0001 compared with PCR). Meanwhile, when both GM and PCR were positive for the same patient, the specificity increased to 98%, which was not significantly different compared to the specificity of at least 2 positive GM (95%, P = .56 for the comparison) or PCR results (93%, P = .07 for the comparison). CONCLUSIONS: When screening high-risk patients for IA with GM and PCR tests, the absence of any positive test can obviate the need for antifungal agents with a negative predictive value of 100%, whereas the presence of at least 2 positive results is highly suggestive of an active infection with a positive predictive value of 88%.

Diagnosis of invasive aspergillosis: recent developments and ongoing challenges.

BACKGROUND: Invasive aspergillosis is an infection with high morbidity and mortality that affects mostly immunocompromised individuals. Early identification and targeted treatment of the infection is essential to improve survival of affected patients. The purpose of our review is to highlight the most recent developments in diagnosis and screening for invasive aspergillosis (IA) along with the challenges associated with the development and validation of novel diagnostic approaches. METHODS: Ovid MEDLINE and The Cochrane library were searched for studies that evaluated serologic, molecular and novel methodologies for the diagnosis of IA. RESULTS: Traditional diagnostic approaches, such as histopathology and culture, are still considered the gold standard but lack sufficient sensitivity. Newer serologic techniques, such as galactomannan (GM) and beta-glucan, have already been incorporated into clinical guidelines, but recent evidence suggests that their performance might be limited in certain clinical settings. Molecular methods, such as the Aspergillus spp. polymerase chain reaction (PCR), have not yet found their place in clinical practice mainly due to lack of standardization. Novel methodologies, such as volatile organic compound detection and lateral flow devices, have recently been developed and promise noninvasive and rapid diagnosis of aspergillosis, while diagnostic algorithms that incorporate both GM and PCR have proven to be effective in early randomized trials as screening methods and can reduce the use of antifungal agents. CONCLUSIONS: Diagnosis of IA remains challenging. Novel methodologies and the standardization of GM and PCR might provide more reliable diagnostic tools in the future.

Invertebrate models of fungal infection.

The morbidity, mortality and economic burden associated with fungal infections, together with the emergence of fungal strains resistant to current antimicrobial agents, necessitate broadening our understanding of fungal pathogenesis and discovering new agents to treat these infections. Using invertebrate hosts, especially the nematode Caenorhabditis elegans and the model insects Drosophila melanogaster and Galleria mellonella, could help achieve these goals. The evolutionary conservation of several aspects of the innate immune response between invertebrates and mammals makes the use of these simple hosts an effective and fast screening method for identifying fungal virulence factors and testing potential antifungal compounds. The purpose of this review is to compare several model hosts that have been used in experimental mycology to-date and to describe their different characteristics and contribution to the study of fungal virulence and the detection of compounds with antifungal properties. This article is part of a Special Issue entitled: Animal Models of Disease.

Antimicrobial lock solutions as a method to prevent central line-associated bloodstream infections: a meta-analysis of randomized controlled trials.

BACKGROUND: Antimicrobial lock solutions may be an effective strategy to prevent catheter-associated infections. However, there remains concern about their efficacy and safety. METHODS: To investigate the efficacy of antimicrobial lock therapy to prevent central line-associated bloodstream infections (CLABSIs), we performed a systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov, from the earliest date up to 31 December 2013. Studies were eligible if they were randomized controlled trials comparing antimicrobial lock solutions to heparin and if they provided an appropriate definition of infection. RESULTS: The 23 included studies reported data on 2896 patients, who were predominantly adult patients undergoing hemodialysis (16/23 studies), but also adult and pediatric oncology patients, critically ill neonates, and patients receiving total parenteral nutrition. The use of antimicrobial lock solutions led to a 69% reduction in CLABSI rate (relative risk [RR], 0.31; 95% confidence interval [CI], .24-.40) and a 32% reduction in the rate of exit site infections (RR, 0.68; 95% CI, .49-.95) compared with heparin, without significantly affecting catheter failure due to noninfectious complications (RR, 0.83; 95% CI, .65-1.06). All-cause mortality was not different between the groups (RR, 0.84; 95% CI .64-1.12). Neither the type of antimicrobial solution nor the population studied, affected the relative reduction in CLABSIs, which also remained significant among studies reporting baseline infection rates of <1.15 per 1000 catheter-days, and studies providing data for catheter-related bloodstream infections. Publication and selective reporting bias are a concern in our study and should be acknowledged. CONCLUSIONS: Antimicrobial lock solutions are effective in reducing risk of CLABSI, and this effect appears to be additive to traditional prevention measures.

Activity of daptomycin or linezolid in combination with rifampin or gentamicin against biofilm-forming Enterococcus faecalis or E. faecium in an in vitro pharmacodynamic model using simulated endocardial vegetations and an in vivo survival assay using Galleria mellonella larvae.

Enterococci are the third most frequent cause of infective endocarditis. A high-inoculum stationary-phase in vitro pharmacodynamic model with simulated endocardial vegetations was used to simulate the human pharmacokinetics of daptomycin at 6 or 10 mg/kg of body weight/day or linezolid at 600 mg every 12 h (q12h), alone or in combination with gentamicin at 1.3 mg/kg q12h or rifampin at 300 mg q8h or 900 mg q24h. Biofilm-forming, vancomycin-susceptible Enterococcus faecalis and vancomycin-resistant Enterococcus faecium (vancomycin-resistant enterococcus [VRE]) strains were tested. At 24, 48, and 72 h, all daptomycin-containing regimens demonstrated significantly more activity (decline in CFU/g) than any linezolid-containing regimen against biofilm-forming E. faecalis. The addition of gentamicin to daptomycin (at 6 or 10 mg/kg) in the first 24 h significantly improved bactericidal activity. In contrast, the addition of rifampin delayed the bactericidal activity of daptomycin against E. faecalis, and the addition of rifampin antagonized the activities of all regimens against VRE at 24 h. Also, against VRE, the addition of gentamicin to linezolid at 72 h improved activity and was bactericidal. Rifampin significantly antagonized the activity of linezolid against VRE at 72 h. In in vivo Galleria mellonella survival assays, linezolid and daptomycin improved survival. Daptomycin at 10 mg/kg improved survival significantly over that with linezolid against E. faecalis. The addition of gentamicin improved the efficacy of daptomycin against E. faecalis and those of linezolid and daptomycin against VRE. We conclude that in enterococcal infection models, daptomycin has more activity than linezolid alone. Against biofilm-forming E. faecalis, the addition of gentamicin in the first 24 h causes the most rapid decline in CFU/g. Of interest, the addition of rifampin decreased the activity of daptomycin against both E. faecalis and VRE.

PCR in diagnosis of invasive aspergillosis: a meta-analysis of diagnostic performance.

Invasive aspergillosis is a difficult-to-diagnose infection with a high mortality rate that affects high-risk groups such as patients with neutropenia and hematologic malignancies. We performed a bivariate meta-analysis of diagnostic data for an Aspergillus sp. PCR assay with blood specimens from high-risk hematology patients. We included all studies involving human subjects that assessed the performance of any PCR assay for invasive aspergillosis in whole blood or serum and that used the European Organization for the treatment of Cancer/Mycoses Study Group criteria as a reference standard. Three investigators independently searched the literature for eligible studies and extracted the data. Out of a total of 37 studies, 25 met strict quality criteria and were included in our evidence synthesis. Twenty-five studies with 2,595 patients were analyzed. The pooled diagnostic performance of whole-blood and serum PCR assays was moderate, with a sensitivity and specificity of 84% (95% confidence interval [CI], 75 to 91%) and 76% (95% CI, 65 to 84%), respectively, suggesting that a positive or negative result is unable, on its own, to confirm or exclude a suspected infection. The performance of a PCR assay of serum was not significantly different from that of whole blood. Notably, at least two positive PCR test results were found to have a specificity of 95% and a sensitivity of 64% for invasive infection, achieving a high positive likelihood ratio of 12.8. Importantly, the European Aspergillus PCR Initiative (EAPCRI) recommendations improved the performance of the PCR even further when at least two positive specimens were used to define PCR positivity. In conclusion, two positive PCR results should be considered highly indicative of an active Aspergillus sp. infection. Use of the EAPCRI recommendations by clinical laboratories can further enhance PCR performance.

Neurocardiac Axis Physiology and Clinical Applications.

The neurocardiac axis constitutes the neuronal circuits between the arteries, heart, brain, and immune organs (including thymus, spleen, lymph nodes, and mucosal associated lymphoid tissue) that together form the cardiovascular brain circuit. This network allows the individual to maintain homeostasis in a variety of environmental situations. However, in dysfunctional states, such as exposure to environments with chronic stressors and sympathetic activation, this axis can also contribute to the development of atherosclerotic vascular disease as well as other cardiovascular pathologies and it is increasingly being recognized as an integral part of the pathogenesis of cardiovascular disease. This review article focuses on 1) the normal functioning of the neurocardiac axis; 2) pathophysiology of the neurocardiac axis; 3) clinical implications of this axis in hypertension, atherosclerotic disease, and heart failure with an update on treatments under investigation; and 4) quantification methods in research and clinical practice to measure components of the axis and future research areas.

Expanded genetic testing in familial hypercholesterolemia-A single center's experience.

Objective: Assess the yield of genetic testing for pathogenic variants in ABCG5, ABCG8, LIPA, and APOE in individuals with personal and family histories suggestive of familial hypercholesterolemia. Methods: Retrospective review of patients seen in the Advanced Lipid Disorders Clinic at Johns Hopkins. Results: In the lipid clinic at a single center during the years 2015-2023, 607 patients underwent genetic testing for familial hypercholesterolemia, of which 263 underwent the expanded genetic testing for sitosterolemia. Eighty-eight patients had genetic testing which included APOE, and 22 patients had testing which included LIPA. Among these, one patient was identified to have a pathogenic variant in APOE and another patient with a pathogenic variant in ABCG5 (0.7 % yield). The frequency of a positive result was double that of a variant of uncertain significance. Conclusion: These data suggest in rare cases expanded testing can provide answers for patients and families with a minimal likelihood of a variant of uncertain significance.

A transcriptional enhancer regulates cardiac maturation.

Cardiomyocyte maturation is crucial for generating adult cardiomyocytes and the application of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). However, regulation at the cis-regulatory element level and its role in heart disease remain unclear. Alpha-actinin 2 (ACTN2) levels increase during CM maturation. In this study, we investigated a clinically relevant, conserved ACTN2 enhancer's effects on CM maturation using hPSC and mouse models. Heterozygous ACTN2 enhancer deletion led to abnormal CM morphology, reduced function and mitochondrial respiration. Transcriptomic analyses in vitro and in vivo showed disrupted CM maturation and upregulated anabolic mammalian target for rapamycin (mTOR) signaling, promoting senescence and hindering maturation. As confirmation, ACTN2 enhancer deletion induced heat shock protein 90A expression, a chaperone mediating mTOR activation. Conversely, targeting the ACTN2 enhancer via enhancer CRISPR activation (enCRISPRa) promoted hPSC-CM maturation. Our studies reveal the transcriptional enhancer's role in cardiac maturation and disease, offering insights into potentially fine-tuning gene expression to modulate cardiomyocyte physiology.