Hypoplastic left heart syndrome (HLHS) is the most lethal congenital heart disease (CHD) whose genetic basis remains elusive, likely due to oligogenic complexity. To identify regulators of cardiomyocyte (CM) proliferation relevant to HLHS, we performed a genome-wide siRNA screen in human iPSC-derived CMs, revealing ribosomal protein (RP) genes as the most prominent effectors of CM proliferation. Whole-genome sequencing of 25 HLHS proband–parent trios similarly showed enrichment of rare RP gene variants, including a damaging RPS15A promoter variant shared in a familial CHD case. Cross-species functional analyses demonstrated that perturbation of RP genes impairs cardiac growth: knockdown of RPS15A, RPS17, RPL26L1, RPL39, or RPS15 reduced CM proliferation, caused cardiac malformations in Drosophila, and produced hypoplastic or dysfunctional hearts in zebrafish. Genetic interactions between RP genes and key cardiac transcription factors (TBX5 and NKX2–7) further support their developmental role. Importantly, p53 suppression or Hippo activation partially rescued RP deficiency phenotypes. Together, these findings implicate RP genes as critical regulators of cardiogenesis and candidate contributors to HLHS.

Drs. Thompson and Kwiatkowski contributed equally. Introduction: Beti-cel gene therapy is a one-time treatment for transfusion-dependent β-thalassemia (TDT) that adds functional copies of the β-globin gene (βT87Q) to address the underlying cause of disease. Here, we report long-term outcomes of participants treated with beti-cel with up to 10 years of follow-up. Methods: After completion of a 2-year phase 1/2 (HGB-204 [NCT01745120]; HGB-205 [NCT02151526]) or phase 3 (HGB-207 [NCT02906202]; HGB-212 [NCT03207009]) beti-cel parent study, treated participants were eligible for the long-term, 13-year follow-up study LTF-303 (NCT02633943). Clinical efficacy, iron homeostasis, health-related quality of life (HRQOL), and safety are reported through last follow-up visit. Key outcomes were also examined by genotype (β0/β0 vs non-β0/β0) and by participant age at enrollment (pediatric: <12 years; adolescent: ≥12 years to <18 years; adult: ≥18 years). Results:As of Feb 2024, 63 participants (median [range] age: 17 [4-35] years) had received beti-cel and subsequently enrolled in LTF-303 (median [range] follow-up: 71.2 [34.5-121.4] months); 2 participants had 10 years of follow-up, 51 (81.0%) participants had at least 5 years of follow-up, and 1 participant withdrew consent after 39 months of follow-up due to personal reasons. Peripheral blood vector copy number (PB VCN) and HbAT87Q levels were stable by month 6 after infusion, sustained across studies up to 10 years, and were higher in phase 3 versus phase 1/2 studies following beti-cel drug product manufacturing optimization, which is similar to the commercial process. At last follow-up, median (range) PB VCN was 0.4 (0.1-4.9) c/dg and 1.6 (0.1-4.8) c/dg in phase 1/2 and phase 3, respectively. Among participants who achieved transfusion independence (TI) in phase 1/2 studies (15/22 [68.2%]), median (range) HbAT87Q was 7.6 (3.9-10.8) g/dL and weighted average hemoglobin (Hb) during TI was 10.24 (9.1-13.1) g/dL. In phase 3 studies, 37/41 (90.2%) participants achieved TI, median (range) HbAT87Q was 9.8 (5.1-14.3) g/dL, and weighted average Hb during TI was 11.24 (9.8-13.9) g/dL. Transduction efficiency, pharmacodynamics, TI rate, and weighted average Hb were similar across genotypes and ages. While iron overload management was at the physician's discretion, 28/37 (78.4%) phase 3 participants who achieved TI are no longer receiving iron-chelation therapy, and of those 28, 22 (78.6%) had liver iron concentration (LIC) <5 mg Fe/g dry weight (dw). Among phase 1/2 and phase 3 participants who achieved and maintained TI and had baseline data, median (range) change from baseline in serum ferritin at month 24 was -907.9 (-5014 to 5539) ng/mL (n=51). At month 60, median (range) change from baseline in serum ferritin and LIC were -1951.0 (-7079 to 1345) ng/mL (n=39) and -2.2 (-20.6 to 9.6) mg Fe/g dw (n=30), respectively, indicating improvement in iron overload. Cardiac T2* remained stable and was >20 msec at last follow-up in all participants who achieved TI, including 2 participants with cardiac T2* ≤20 msec at baseline. Among participants who achieved TI and had HRQOL data, clinically meaningful improvements were reported in Short Form-36 Health Survey Questionnaire (SF-36) scores at month 24 for the mental component summary and at month 36 for physical component summary (mean score increase >2). Participants had sustained SF-36 physical and emotional scores above the normative population mean (50) at month 60. Clinically meaningful improvements in Pediatric Quality of Life Inventory total scores were reported at month 36, and scores remained above the normative population mean (81) at month 60. All 26 participants who achieved TI and completed a questionnaire reported an overall benefit with beti-cel. No beti-cel-related serious adverse events were reported >2 years after infusion through last follow-up. No malignancies, insertional oncogenesis, or vector-derived replication-competent lentivirus were reported. Conclusion: These data provide evidence of the sustained favorable benefit-risk profile of gene addition therapy with beti-cel in participants with TDT and will inform real-world treatment decisions.Beti-cel is a potentially curative gene addition therapy for patients with TDT across genotypes and ages through achievement of durable TI, normal or near-normal Hb, and a favorable long-term safety profile with up to 10 years of follow-up.

Background: Deciphering hypoplastic left heart syndrome (HLHS) pathogenesis is confounded by its genetic heterogeneity and oligogenic underpinnings. Methods: Whole genome sequences were analyzed by 3 independent strategies to identify HLHS gene candidates, ranked by variant, gene, and disease-level metrics. Results: First, a genome-wide association study of 174 cases and 853 controls revealed suggestive association with a MYO18B intron 33 variant (rs2269628-G; frequency=0.55 versus 0.39; OR, 1.97 [95% CI, 1.54–2.52]; P =6.70×10 − 8 ). Second, transmission disequilibrium testing of 161 HLHS proband-parent trios revealed overrepresentation of a MYO18B intron 42 variant (rs73154186-A; frequency=0.05; OR, 24 [95% CI, 3.2–177.4]; P =4.23×10 − 6 ). Third, rare, predicted-damaging variants were filtered in 2 multiplex families. In 141H, 2 fifth-degree relatives with HLHS shared a paternally-inherited MYO5A missense variant (p.Arg801Trp; frequency=0.00003; combined annotation-dependent depletion score=29), each with a maternally-inherited or de novo candidate modifier variant in a MYO5A-interacting conventional myosin. In 442H, a HLHS proband was compound heterozygous for MYO15A variants—a maternally-inherited pathogenic stop-gain variant co-segregating with tetralogy of Fallot and bicuspid aortic valve in maternal relatives (p.Tyr2819Ter; frequency=0.00003) and a paternally-inherited intronic variant altering a canonical transcription factor binding site (rs1277068603; frequency=0.00001; position weight matrix score=0.98). Conclusions: Collectively, these findings suggest that common and rare alleles within unconventional myosin genes are associated with HLHS susceptibility. The identified candidate MYO18B regulates cardiac sarcomerogenesis, supporting the hypothesis of intrinsic myogenic perturbation in arrested left heart development.

Rare familial spontaneous coronary artery dissection (SCAD) kindreds implicate genetic disease predisposition and provide a unique opportunity for candidate gene discovery. Whole-genome sequencing was performed in fifteen probands with non-syndromic SCAD who had a relative with SCAD, eight of whom had a second relative with extra-coronary arteriopathy. Co-segregating variants and associated genes were prioritized by quantitative variant, gene, and disease-level metrics. Curated public databases were queried for functional relationships among encoded proteins. Fifty-four heterozygous coding variants in thirteen families co-segregated with disease and fulfilled primary filters of rarity, gene variation constraint, and predicted-deleterious protein effect. Secondary filters yielded 11 prioritized candidate genes in 12 families, with high arterial tissue expression (n = 7), high-confidence protein-level interactions with genes associated with SCAD previously (n = 10), and/or previous associations with connective tissue disorders and aortopathies (n = 3) or other vascular phenotypes in mice or humans (n = 11). High-confidence associations were identified among 10 familial SCAD candidate-gene-encoded proteins. A collagen-encoding gene was identified in five families, two with distinct variants in COL4A2. Familial SCAD is genetically heterogeneous, yet perturbations of extracellular matrix, cytoskeletal, and cell–cell adhesion proteins implicate common disease-susceptibility pathways. Incomplete penetrance and variable expression suggest genetic or environmental modifiers.

Cell Therapy and Transplant Section, Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA

Revaccination after hematopoietic cell transplantation (HCT) is critical to prevent morbidity and mortality from vaccine-preventable illnesses. The global aim of our quality improvement initiative was to enhance timely, correct, and effective revaccination after pediatric HCT. The SMART aim of our project was to decrease median unvaccinated time by 4 months by decreasing the time to vaccine eligibility, time from eligibility to vaccine initiation, and time to completion of the vaccine series. A multidisciplinary group performed a cross-sectional quantitative and qualitative evaluation of revaccination practices at our institution. We identified factors associated with delayed, incorrect, or incomplete revaccination. Several plan-do-study-act interventions were implemented to address these drivers, including revising immune readiness criteria, increasing auditing of primary care administered immunizations, and, importantly, establishing a dedicated revaccination clinic within the HCT clinic at our center. The time to vaccine eligibility decreased from 12.6 months to 10 months (a 20% decrease), and the time to complete the vaccine series decreased from 19.3 months to 15.7 months (a 19% decrease). With a quality improvement initiative, we addressed the many causes of delayed or incomplete revaccination post-HCT and through a team-based approach successfully decreased the time to vaccine start and time to vaccine completion at our center.

The use of thiotepa-treosulfan-fludarabine conditioning regimen and peripheral blood stem cell grafts is associated with improved outcomes of hematopoietic stem cell transplantation (HCT) in patients with high-risk thalassemia major. However, there remains a need to identify predictors of poor outcomes in this cohort to further optimize outcomes. The Endothelial Activation and Stress Index (EASIX) is a biomarker shown to predict survival in various settings, including graft-versus-host disease, veno-occlusive disease, and nonrelapse mortality following allogeneic HCT. In this retrospective analysis, we evaluated the role of EASIX-PreTx (measured before conditioning therapy) as a biomarker in predicting day +100 transplantation-related mortality (TRM+100) in 281 patients with thalassemia major who underwent HCT with a uniform conditioning regimen using thiotepa-treosulfan-fludarabine at our center between January 2012 and December 2019. The median patient age was 9 years (range, 1 to 25 years), and 109 (38.8%) were females. According to the Pesaro classification (with Vellore modification), 3 patients (1.1%) were class I, 34 (12.1%) were class II, 134 (47.7%) were class III low risk, and 110 (39.1%) were class III high risk. Stem cell donors were matched sibling (n = 218; 77.6%), matched related nonsibling (n = 23; 8.2%), or matched unrelated (n = 40; 14.2%). Five patients (1.8%) received a bone marrow graft, and the others received a peripheral blood stem cell graft. Thirty-eight patients (13.5%) had TRM+100. EASIX-PreTx was available for 184 patients (65.5%). The median EASIX-PreTx was significantly higher in patients with TRM+100 compared with those without TRM+100 (1.09 versus .75; P = .008). An EASIX-PreTx cutoff of .85 had 70.4% sensitivity and 62% specificity for predicting TRM+100. The TRM+100 for patients with EASIX-PreTx >.85 was significantly higher than those with EASIX <.85 (24.4% versus 7.5%; P = .003). In a uniform subgroup of class III patients undergoing allogeneic HCT (n = 156), EASIX-PreTx was an independent predictor of TRM+100.

Spontaneous coronary artery dissection (SCAD) is an understudied cause of myocardial infarction primarily affecting women. It is not known to what extent SCAD is genetically distinct from other cardiovascular diseases, including atherosclerotic coronary artery disease (CAD). Here we present a genome-wide association meta-analysis (1,917 cases and 9,292 controls) identifying 16 risk loci for SCAD. Integrative functional annotations prioritized genes that are likely to be regulated in vascular smooth muscle cells and artery fibroblasts and implicated in extracellular matrix biology. One locus containing the tissue factor gene F3, which is involved in blood coagulation cascade initiation, appears to be specific for SCAD risk. Several associated variants have diametrically opposite associations with CAD, suggesting that shared biological processes contribute to both diseases, but through different mechanisms. We also infer a causal role for high blood pressure in SCAD. Our findings provide novel pathophysiological insights involving arterial integrity and tissue-mediated coagulation in SCAD and set the stage for future specific therapeutics and preventions.

Intravitreal anti-vascular endothelial growth factor (VEGF) injections are commonly used to treat eyes with macular edema secondary to hemiretinal vein occlusion (HRVO) or central retinal vein occlusion (CRVO). Information on whether differences exist in outcomes after anti-VEGF therapy can help guide treatment for each of the different disease types.To compare baseline characteristics, treatment burden, and outcomes of macular edema treatment in participants with HRVO with those of participants with CRVO.This post hoc outcome analysis from the Study of Comparative Treatments for Retinal Vein Occlusion 2 randomized clinical trial included 362 participants with macular edema caused by HRVO or CRVO treated at 66 US sites. Randomization began in September 2014, and the last month 24 follow-up visit occurred in February 2018. Data were analyzed from April 2020 to May 2021.Eyes were initially randomized to 6 monthly intravitreal injections of aflibercept or bevacizumab and were treated according to protocol between months 6 to 12 depending on 6-month outcome. After month 12, patients were treated per investigator discretion and observed through month 60.Mean visual acuity letter score (VALS).Of 362 included patients, 157 (43.4%) were female, and the mean (SD) age was 68.9 (12.0) years. Outcome data were analyzed up to month 24 owing to substantial missing data at later visits. A significantly greater proportion of participants with HRVO than those with CRVO were Black (37% vs 11%). Treatment rates between months 12 to 23 were 0.36 (95% CI, 0.32-0.40) injections per month for patients with CRVO and 0.28 (95% CI, 0.19-0.36) for patients with HRVO (P = .11). The mean VALS from months 1 to 24 of an HRVO study eye exceeded that of a CRVO study eye by 5.5 (95% CI, 1.5-9.5; P = .01), consistent with the magnitude of the VALS difference between eyes with CRVO and HRVO at baseline. Eyes with CRVO presented at baseline with more macular edema than eyes with HRVO (difference in central subfield thickness [CST], 86 μm; 95% CI, 48-124; P < .001), with no difference in CST between the groups throughout months 1 to 24.Black race was more prevalent among participants with HRVO than CRVO, and no differences were observed in the frequency of treatments for macular edema between eyes with CRVO and HRVO. Although eyes with CRVO presented with worse visual acuity and more macular edema on average than did eyes with HRVO, the magnitude of VALS improvement, central retinal thickness in response to anti-VEGF therapy, and treatment burden were similar between the groups.

Background: Whole-genome sequencing in families enables deciphering of congenital heart disease causes. A shared genetic basis for familial bicuspid aortic valve (BAV) and hypoplastic left heart syndrome (HLHS) was postulated. Methods: Whole-genome sequencing was performed in affected members of 6 multiplex BAV families, an HLHS cohort of 197 probands and 546 relatives, and 813 controls. Data were filtered for rare, predicted-damaging variants that cosegregated with familial BAV and disrupted genes associated with congenital heart disease in humans and mice. Candidate genes were further prioritized by rare variant burden testing in HLHS cases versus controls. Modifier variants in HLHS proband-parent trios were sought to account for the severe developmental phenotype. Results: In 5 BAV families, missense variants in 6 ontologically diverse genes for structural ( SPTBN1 , PAXIP1 , and FBLN1 ) and signaling ( CELSR1 , PLXND1 , and NOS3 ) proteins fulfilled filtering metrics. CELSR1 , encoding cadherin epidermal growth factor laminin G seven-pass G-type receptor, was identified as a candidate gene in 2 families and was the only gene demonstrating rare variant enrichment in HLHS probands ( P =0.003575). HLHS-associated CELSR1 variants included 16 missense, one splice site, and 3 noncoding variants predicted to disrupt canonical transcription factor binding sites, most of which were inherited from a parent without congenital heart disease. Filtering whole-genome sequencing data for rare, predicted-damaging variants inherited from the other parent revealed 2 cases of CELSR1 compound heterozygosity, one case of CELSR1 - CELSR3 synergistic heterozygosity, and 4 cases of CELSR1 - MYO15A digenic heterozygosity. Conclusions: CELSR1 is a susceptibility gene for familial BAV and HLHS, further implicating planar cell polarity pathway perturbation in congenital heart disease.

BACKGROUND The objective of this study is to assess the safety and early impact of intramyocardial delivery of autologous bone marrow-derived mononuclear cells (BM-MNC) at time of surgical Ebstein repair.METHODS Patients with Ebstein anomaly (ages 6 months to 30 years) scheduled to undergo repair of the tricuspid valve were eligible to participate in this open-label, non-randomized phase I clinical trial. BM-MNC target dose was 1-3 million cells/kg. Ten patients have undergone surgical intervention and cell delivery to the right ventricle (RV) and completed 6-month follow-up.RESULTS All patients underwent surgical tricuspid valve repair and uneventful BM-MNC delivery; there were no ventricular arrhythmias and no adverse events related to study product or delivery. Echocardiographic RV myocardial performance index improved and RV fractional area change showed an initial decline and then through study follow-up. There was no evidence of delayed myocardial enhancement or regional wall motion abnormalities at injection sites on 6 month follow-up magnetic resonance imaging.CONCLUSIONS Intramyocardial delivery of BM-MNC after surgical repair in Ebstein anomaly can be performed safely. Echocardiography variables suggest a positive impact of cell delivery on the RV myocardium with improvements in both RV size and wall motion over time. Additional follow-up and comparison to control groups are required to better characterize the impact of cell therapy on the myopathic RV in Ebstein anomaly.(Ann Thorac Surg 2022;113:890-5)(c) 2022 by The Society of Thoracic Surgeons

Ribonucleoprotein (RNP) granules are biomolecular condensates-liquid-liquid phase-separated droplets that organize and manage messenger RNA metabolism, cell signaling, biopolymer assembly, biochemical reactions and stress granule responses to cellular adversity. Dysregulated RNP granules drive neuromuscular degenerative disease but have not previously been linked to heart failure. By exploring the molecular basis of congenital dilated cardiomyopathy (DCM) in genome-edited pigs homozygous for an RBM20 allele encoding the pathogenic R636S variant of human RNA-binding motif protein-20 (RBM20), we discovered that RNP granules accumulated abnormally in the sarcoplasm, and we confirmed this finding in myocardium and reprogrammed cardiomyocytes from patients with DCM carrying the R636S allele. Dysregulated sarcoplasmic RBM20 RNP granules displayed liquid-like material properties, docked at precisely spaced intervals along cytoskeletal elements, promoted phase partitioning of cardiac biomolecules and fused with stress granules. Our results link dysregulated RNP granules to myocardial cellular pathobiology and heart failure in gene-edited pigs and patients with DCM caused by RBM20 mutation.

Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, inherited bone marrow failure syndrome. Hematopoietic stem cell transplantation (HSCT) is considered a curative treatment option, but existing descriptions of patient and transplant characteristics and outcomes after related and unrelated donor HSCT are sparse. We describe outcomes after HSCT for congenital amegakaryocytic thrombocytopenia (CAMT; n = 86) from 2000 to 2018. We conducted an analysis of data collected by the Center for International Blood and Marrow Transplant Research on patients with CAMT receiving therapeutic allogeneic HSCT. The predominant donor type was HLA-matched or mismatched unrelated donors (n = 58, 67%). The remaining included HLA-matched sibling (n = 23, 27%) and HLA-mismatched relative (n = 5, 6%). The predominant graft types were bone marrow (n = 53, 62%) and cord blood (n = 25, 29%). The median age at transplantation was 3 years, with 82 of 86 patients being transplanted aged ≤10 years. The 5-year graft failure-free and overall survival were 83% (95% confidence interval [CI], 74-90) and 86% (95% CI, 78-93), respectively. An examination for risk factors confirmed mortality was higher after HLA-mismatched relative and mismatched unrelated donor HSCT compared to HLA-matched sibling and matched unrelated donor HSCT (hazard ratio 3.52, P = .04; 75% versus 93%). The 1-year incidence of graft failure was 19% after HLA-mismatched HSCT (n = 32) compared to 7% after HLA-matched HSCT (n = 54, P = .15). Day-100 grade II-IV acute graft-versus-host disease was 13%, 26%, and 30% after HLA-matched sibling, HLA-matched and mismatched unrelated donor HSCT. The 5-year incidence of chronic graft-versus-host disease was 33% with 24 of 28 patients having received grafts from HLA-matched (n = 13) and mismatched unrelated (n = 11) donors. Although HLA-matched donors are preferred, HLA-mismatched donors also extend survival for CAMT.

A de novo missense variant in Rag GTPase protein C (RagCS75Y) was recently identified in a syndromic dilated cardiomyopathy (DCM) patient. However, its pathogenicity and the related therapeutic strategy remain unclear. We generated a zebrafish RragcS56Y (corresponding to human RagCS75Y) knock-in (KI) line via TALEN technology. The KI fish manifested cardiomyopathy-like phenotypes and poor survival. Overexpression of RagCS75Y via adenovirus infection also led to increased cell size and fetal gene reprogramming in neonatal rat ventricle cardiomyocytes (NRVCMs), indicating a conserved mechanism. Further characterization identified aberrant mammalian target of rapamycin complex 1 (mTORC1) and transcription factor EB (TFEB) signaling, as well as metabolic abnormalities including dysregulated autophagy. However, mTOR inhibition failed to ameliorate cardiac phenotypes in the RagCS75Y cardiomyopathy models, concomitant with a failure to promote TFEB nuclear translocation. This observation was at least partially explained by increased and mTOR-independent physical interaction between RagCS75Y and TFEB in the cytosol. Importantly, TFEB overexpression resulted in more nuclear TFEB and rescued cardiomyopathy phenotypes. These findings suggest that S75Y is a pathogenic gain-of-function mutation in RagC that leads to cardiomyopathy. A primary pathological step of RagCS75Y cardiomyopathy is defective mTOR–TFEB signaling, which can be corrected by TFEB overexpression, but not mTOR inhibition.

Bicuspid aortic valve (BAV) is the most common congenital heart defect in children, adolescents, and adults. (1) It is a heterogeneous disease that affects both the aortic valve and the aorta. It can lead to many complications, including aortic valve stenosis, regurgitation, or endocarditis. (2)( 3) It also can lead to dilation of the aorta, predisposing individuals to a significantly higher risk of aortic aneurysm and dissection. (4) Althoughmost individuals with BAV present with these long-term complications during adulthood, a considerable number of patients may also present during childhood and adolescence with early-onset disease; that may require interventions in up to 12% to 15% of the patients. (5)(6) Therefore, patients with BAV require lifelong follow-up and surveillance. BAV has multiple implications in terms of sports participation and family screening, making it an important subject for primary care providers. This article reviews the anatomy, genetics, presentation, diagnosis, and management of BAV in infants, children, and adolescents.