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Introduction: Preoperative risk stratification in congenital cardiac surgery includes patient and procedure related factors, which may be used in clinical decision making as well program performance evaluation. Despite these tools, unidentified factors contribute to wide variation in outcomes both within and between centers. Identification of latent physiologic risk factors may strengthen predictive models. Hypothesis: Total cell-free DNA (TCF) functions as a biomarker for cellular injury as well as a pro-inflammatory cytokine. We hypothesized that elevated preoperative TCF would be associated with poor outcome following pediatric cardiac surgery requiring cardiopulmonary bypass (CPB). Methods: Prospective observational study of children age < 18 yr and wt > 3 kg undergoing planned CPB surgery. The Children’s Wisconsin Institutional Review Board approved the protocol . A serum TCF sample was obtained after induction of anesthesia prior to surgical incision. The primary outcome measure was a composite of postoperative cardiac arrest, ECMO, or death (CAED). Association of outcome to TCF was assessed by logistic regression with a cutpoint chosen by ROC curve exploration. Odds ratios with 95% CI were calculated. Results: Data were available in 117 patients, median age 0.9 years (range 0-17.4), median weight 7.8kg (range 3.2-98). The primary outcome (CAED) was met in 6/117 (5.1%). Table 1 summarizes characteristics of patients with and without CAED. Risk of CAED was 2% with TCF20 ng/ml (OR=18.2, CI 2.2- 212, p Conclusions: Preoperative TCF has an important association with postoperative cardiac arrest, ECMO, and death. Alternative or intensified treatment strategies could be considered in patients with elevated preoperative TCF.

Congenital Heart Disease (CHD) affects approximately 7-9 children per 1000 live births. Numerous genetic studies have established a role for rare genomic variants at the copy number variation (CNV) and single nucleotide variant level. In particular, the role of de novo mutations (DNM) has been highlighted in syndromic and non-syndromic CHD. To identify novel haploinsufficient CHD disease genes we performed an integrative analysis of CNVs and DNMs identified in probands with CHD including cases with sporadic thoracic aortic aneurysm (TAA). We assembled CNV data from 7,958 cases and 14,082 controls and performed a gene-wise analysis of the burden of rare genomic deletions in cases versus controls. In addition, we performed mutation rate testing for DNMs identified in 2,489 parent-offspring trios. Our combined analysis revealed 21 genes which were significantly affected by rare genomic deletions and/or constrained non-synonymous de novo mutations in probands. Fourteen of these genes have previously been associated with CHD while the remaining genes (FEZ1, MYO16, ARID1B, NALCN, WAC, KDM5B and WHSC1) have only been associated in singletons and small cases series, or show new associations with CHD. In addition, a systems level analysis revealed shared contribution of CNV deletions and DNMs in CHD probands, affecting protein-protein interaction networks involved in Notch signaling pathway, heart morphogenesis, DNA repair and cilia/centrosome function. Taken together, this approach highlights the importance of re-analyzing existing datasets to strengthen disease association and identify novel disease genes.

Elevated total cell-free DNA (TCF) concentration has been associated with critical illness in adults and elevated donor fraction (DF), the ratio of donor specific cell-free DNA to total cell-free DNA present in the recipient's plasma, is associated with rejection following cardiac transplantation. This study investigates relationships between TCF and clinical outcomes after heart transplantation.A prospective, blinded, observational study of 87 heart transplantation recipients was performed. Samples were collected at transplantation, prior to endomyocardial biopsy, during treatment for rejection, and at hospital readmissions. Longitudinal clinical data were collected and entered into a RedCAP (Vanderbilt University) database. TCF and DF levels were correlated with endomyocardial biopsy and angiography results, as well as clinical outcomes. Logistic regression for modeling and repeated measures analysis using generalized linear modeling was used. The standard receiver operating characteristic curve, hazard ratios, and odds ratios were calculated.There were 257 samples from 87 recipients analyzed. TCF greater than 50 ng/mL were associated with increased mortality (P = .01, area under the curve 0.93, sensitivity 0.44, specificity 0.97) and treatment for infection (P.005, area under the curve 0.68, sensitivity 0.45, specificity 0.96). Increased DF was not correlated with treatment for infection. DF was associated with rejection and cardiac allograft vasculopathy (P.001), but TCF was not.TCF elevation predicted death and treatment for infection. DF elevation predicted histopathologic acute rejection and cardiac allograft vasculopathy. Surveillance of TCF and DF levels may inform treatment after heart transplantation.

Heart transplantation is a well‐established therapy for end‐stage heart failure in children and young adults. The highest risk of graft loss occurs in the first 60 days post‐transplant. Donor fraction of cell‐free DNA is a highly sensitive marker of graft injury. Changes in cell‐free DNA levels have not previously been studied in depth in patients early after heart transplant. A prospective study was conducted among heart transplant recipients at a single pediatric heart center. Blood samples were collected from children and young adult transplant patients at three time points within 10 days of transplantation. DF and total cell‐free DNA levels were measured using a targeted method (myTAIHEART). In 17 patients with serial post‐transplant samples, DF peaks in the first 2 days after transplant (3.5%, [1.9‐10]%) and then declines toward baseline (0.27%, [0.19‐0.52]%) by 6‐9 days. There were 4 deaths in the first year among the 10 patients with complete sample sets, and 3 out of 4 who died had a late rise or blunted decline in donor fraction. Patients who died trended toward an elevated total cell‐free DNA at 1 week (41.5, [34‐65] vs 13.6, [6.2‐22] P = .07). Donor fraction peaks early after heart transplant and then declines toward baseline. Patients without sustained decline in donor fraction and/or elevated total cell‐free DNA at 1 week may have worse outcomes.

Background Ebstein's anomaly (EA) is a rare congenital heart disease of the tricuspid valve and right ventricle. Patients with EA often manifest with left ventricular noncompaction (LVNC), a cardiomyopathy. Despite implication of cardiac sarcomere genes in some cases, very little is understood regarding the genetic etiology of EA/LVNC. Our study describes a multigenerational family with at least 10 of 17 members affected by EA/LVNC. Methods We performed echocardiography on all family members and conducted exome sequencing of six individuals. After identifying candidate variants using two different bioinformatic strategies, we confirmed segregation with phenotype using Sanger sequencing. We investigated structural implications of candidate variants using protein prediction models. Results Exome sequencing analysis of four affected and two unaffected members identified a novel, rare, and damaging coding variant in the Kelch‐like family member 26 (KLHL26) gene located on chromosome 19 at position 237 of the protein (GRCh37). This variant region was confirmed by Sanger sequencing in the remaining family members. KLHL26 (c.709C > T p.R237C) segregates only with EA/LVNC‐affected individuals (FBAT p, Patient's Ebstein's anomaly (EA), a rare congenital heart disease of the tricuspid valve and right ventricle often manifest with left ventricular noncompaction (LVNC), a cardiomyopathy. Our study identifies a novel, rare, and damaging coding variant c.709C > T (p.R237C) in the Kelch‐like family member 26 (KLHL26) gene with 10 affected out of 17 affected members using Sanger sequencing. Through structural modeling, we show that the KLHL26 variant may affect protein binding to Cullin3 (CUL3), a component of E3 ubiquitin ligase in the ubiquitin‐mediated protein degradation.

Lifelong noninvasive rejection monitoring in heart transplant patients is a critical clinical need historically poorly met in adults and unavailable for children and infants. Cell-free DNA (cfDNA) donor-specific fraction (DF), a direct marker of selective donor organ injury, is a promising analytical target. Methodological differences in sample processing and DF determination profoundly affect quality and sensitivity of cfDNA analyses, requiring specialized optimization for low cfDNA levels typical of transplant patients. Using next-generation sequencing, we previously correlated elevated DF with acute cellular and antibody-mediated rejection (ACR and AMR) in pediatric and adult heart transplant patients. However, next-generation sequencing is limited by cost, TAT, and sensitivity, leading us to clinically validate a rapid, highly sensitive, quantitative genotyping test, myTAIHEART®, addressing these limitations. To assure pre-analytical quality and consider interrelated cfDNA measures, plasma preparation was optimized and total cfDNA (TCF) concentration, DNA fragmentation, and DF quantification were validated in parallel for integration into myTAIHEART reporting. Analytical validations employed individual and reconstructed mixtures of human blood-derived genomic DNA (gDNA), cfDNA, and gDNA sheared to apoptotic length. Precision, linearity, and limits of blank/detection/quantification were established for TCF concentration, DNA fragmentation ratio, and DF determinations. For DF, multiplexed high-fidelity amplification followed by quantitative genotyping of 94 SNP targets was applied to 1168 samples to evaluate donor options in staged simulations, demonstrating DF call equivalency with/without donor genotype. Clinical validation studies using 158 matched endomyocardial biopsy-plasma pairs from 76 pediatric and adult heart transplant recipients selected a DF cutoff (0.32%) producing 100% NPV for ≥2R ACR. This supports the assay’s conservative intended use of stratifying low versus increased probability of ≥2R ACR. myTAIHEART is clinically validated for heart transplant recipients ≥2 months old and ≥8 days post-transplant, expanding opportunity for noninvasive transplant rejection assessment to infants and children and to all recipients >1 week post-transplant.

Coarctation of the aorta (CoA) is a common congenital cardiovascular (CV) defect characterized by a stenosis of the descending thoracic aorta. Treatment exists, but many patients develop hypertension (HTN). Identifying the cause of HTN is challenging because of patient variability (e.g., age, follow-up duration, severity) and concurrent CV abnormalities. Our objective was to conduct RNA sequencing of aortic tissue from humans with CoA to identify a candidate gene for mechanistic studies of arterial dysfunction in a rabbit model of CoA devoid of the variability seen with humans. We present the first known evidence of natriuretic peptide receptor C ( NPR-C; aka NPR3) downregulation in human aortic sections subjected to high blood pressure (BP) from CoA versus normal BP regions (validated to PCR). These changes in NPR-C, a gene associated with BP and proliferation, were replicated in the rabbit model of CoA. Artery segments from this model were used with human aortic endothelial cells to reveal the functional relevance of altered NPR-C activity. Results showed decreased intracellular calcium ([Ca2+]i) activity to C-type natriuretic peptide (CNP). Normal relaxation induced by CNP and atrial natriuretic peptide was impaired for aortic segments exposed to elevated BP from CoA. Inhibition of NPR-C (M372049) also impaired aortic relaxation and [Ca2+]i activity. Genotyping of NPR-C variants predicted to be damaging revealed that rs146301345 was enriched in our CoA patients, but sample size limited association with HTN. These results may ultimately be used to tailor treatment for CoA based on mechanical stimuli, genotyping, and/or changes in arterial function.

Numerous genetic studies have established a role for rare genomic variants in Congenital Heart Disease (CHD) at the copy number variation (CNV) and de novo variant (DNV) level. To identify novel haploinsufficient CHD disease genes, we performed an integrative analysis of CNVs and DNVs identified in probands with CHD including cases with sporadic thoracic aortic aneurysm. We assembled CNV data from 7,958 cases and 14,082 controls and performed a gene-wise analysis of the burden of rare genomic deletions in cases versus controls. In addition, we performed variation rate testing for DNVs identified in 2,489 parent-offspring trios. Our analysis revealed 21 genes which were significantly affected by rare CNVs and/or DNVs in probands. Fourteen of these genes have previously been associated with CHD while the remaining genes (FEZ1, MYO16, ARID1B, NALCN, WAC, KDM5B and WHSC1) have only been associated in small cases series or show new associations with CHD. In addition, a systems level analysis revealed affected protein-protein interaction networks involved in Notch signaling pathway, heart morphogenesis, DNA repair and cilia/centrosome function. Taken together, this approach highlights the importance of re-analyzing existing datasets to strengthen disease association and identify novel disease genes and pathways., Author summary Congenital heart disease (CHD) is the most common congenital anomaly and represents a major global health burden. Multiple studies have identified a key genetic component contributing to the aetiology of CHD. However, despite the advances in the field of CHD within the last three decades, the genetic causes underlying CHD are still not fully understood. Herein we have assembled a large patient CHD cohort and performed a data-driven meta-analysis of genomic variants in CHD. This analysis has allowed us to strengthen the disease association of known CHD genes, as well as identifying novel haploinsufficient CHD candidate genes.

Hypoplastic left heart syndrome (HLHS) is a clinically and anatomically severe form of congenital heart disease (CHD). Although prior studies suggest that HLHS has a complex genetic inheritance, its etiology remains largely unknown. The goal of this study was to characterize a risk gene in HLHS and its effect on HLHS etiology and outcome. We performed next-generation sequencing on a multigenerational family with a high prevalence of CHD/HLHS, identifying a rare variant in the α-myosin heavy chain ( MYH6) gene. A case-control study of 190 unrelated HLHS subjects was then performed and compared with the 1000 Genomes Project. Damaging MYH6 variants, including novel, missense, in-frame deletion, premature stop, de novo, and compound heterozygous variants, were significantly enriched in HLHS cases ( P < 1 × 10−5). Clinical outcomes analysis showed reduced transplant-free survival in HLHS subjects with damaging MYH6 variants ( P < 1 × 10−2). Transcriptome and protein expression analyses with cardiac tissue revealed differential expression of cardiac contractility genes, notably upregulation of the β-myosin heavy chain ( MYH7) gene in subjects with MYH6 variants ( P < 1 × 10−3). We subsequently used patient-specific induced pluripotent stem cells (iPSCs) to model HLHS in vitro. Early stages of in vitro cardiomyogenesis in iPSCs derived from two unrelated HLHS families mimicked the increased expression of MYH7 observed in vivo ( P < 1 × 10−2), while revealing defective cardiomyogenic differentiation. Rare, damaging variants in MYH6 are enriched in HLHS, affect molecular expression of contractility genes, and are predictive of poor outcome. These findings indicate that the etiology of MYH6-associated HLHS can be informed using iPSCs and suggest utility in future clinical applications.

There is a compelling clinical need for a noninvasive alternative to endomyocardial biopsy (EMB) for the surveillance of rejection in heart transplant recipients. We and others have reported on donor cell-free deoxyribonucleic acid (cfDNA), which is shed from the donor allograft and is elevated

The clinical significance of copy number variants (CNVs) in congenital heart disease (CHD) continues to be a challenge. Although CNVs including genes can confer disease risk, relationships between gene dosage and phenotype are still being defined. Our goal was to perform a quantitative analysis of CNVs involving 100 well-defined CHD risk genes identified through previously published human association studies in subjects with anatomically defined cardiac malformations. A novel analytical approach permitting CNV gene frequency “spectra” to be computed over prespecified regions to determine phenotype-gene dosage relationships was employed. CNVs in subjects with CHD ( n = 945), subphenotyped into 40 groups and verified in accordance with the European Paediatric Cardiac Code, were compared with two control groups, a disease-free cohort ( n = 2,026) and a population with coronary artery disease ( n = 880). Gains (≥200 kb) and losses (≥100 kb) were determined over 100 CHD risk genes and compared using a Barnard exact test. Six subphenotypes showed significant enrichment ( P ≤ 0.05), including aortic stenosis (valvar), atrioventricular canal (partial), atrioventricular septal defect with tetralogy of Fallot, subaortic stenosis, tetralogy of Fallot, and truncus arteriosus. Furthermore, CNV gene frequency spectra were enriched ( P ≤ 0.05) for losses at: FKBP6, ELN, GTF2IRD1, GATA4, CRKL, TBX1, ATRX, GPC3, BCOR, ZIC3, FLNA and MID1; and gains at: PRKAB2, FMO5, CHD1L, BCL9, ACP6, GJA5, HRAS, GATA6 and RUNX1. Of CHD subjects, 14% had causal chromosomal abnormalities, and 4.3% had likely causal (significantly enriched), large, rare CNVs. CNV frequency spectra combined with precision phenotyping may lead to increased molecular understanding of etiologic pathways.

To the Editor: Approximately 20,000 cardiac transplant recipients currently reside in the United States. Rejection remains a major cause of graft failure and requires lifelong surveillance. The current gold standard for monitoring rejection is catheter-based endomyocardial biopsy (EMB), which is

To test the hypothesis that patients with hypoplastic left heart syndrome (HLHS) and developmental delay will have a higher average summative C-score in ciliopathy genes than patients with HLHS without developmental delay.Ciliopathy gene variant burden was determined utilizing a summative C-score for 14 ciliopathy genes in children with HLHS (n = 24). Mean summative C-scores were compared between children with and without developmental delay. Genome-wide randomizing gene sets were evaluated as a scoring control.Children with developmental delay had a mean summative C-score of 4.05 in ciliopathy genes as compared to a mean summative C-score of 2.02 for children without developmental delay. This difference in means was higher than 99.1% (empirical P value0.01) of 2 million random lists of 14 genes.Genetically complex disorders such as ciliopathies can be assessed to determine phenotypic risk with summative C-score in appropriately chosen gene sets. If these results are replicated in subsequent cohorts, a diagnostic gene panel could identify risk for developmental delay and other ciliopathy-related comorbidities in infants with congenital heart disease.Genet Med advance online publication 27 October 2016Genetics in Medicine (2016); doi:10.1038/gim.2016.167.

Donor fraction (DF) of cell-free DNA (cf-DNA) has been proposed as a noninvasive surveillance method in heart transplantation. We present our pilot experience with a novel assay to quantify DF (%) with a clinically practical throughput and turnaround time. A blinded study was performed in which

The use of human pluripotent cell progeny for cardiac disease modeling, drug testing and therapeutics requires the ability to efficiently induce pluripotent cells into the cardiomyogenic lineage. Although direct activation of the Activin-A and/or Bmp pathways with growth factors yields context-dependent success, recent studies have shown that induction of Wnt signaling using low molecular weight molecules such as CHIR, which in turn induces the Activin-A and Bmp pathways, is widely effective. To further enhance the reproducibility of CHIR-induced cardiomyogenesis, and to ultimately promote myocyte maturation, we are using exogenous growth factors to optimize cardiomyogenic signaling downstream of CHIR induction. As indicated by RNA-seq, induction with CHIR during Day 1 (Days 0-1) was followed by immediate expression of Nodal ligands and receptors, followed later by Bmp ligands and receptors. Co-induction with CHIR and high levels of the Nodal mimetic Activin-A (50-100 ng/ml) during Day 0-1 efficiently induced definitive endoderm, whereas CHIR supplemented with Activin-A at low levels (10 ng/ml) consistently improved cardiomyogenic efficiency, even when CHIR alone was ineffective. Moreover, co-induction using CHIR and low levels of Activin-A apparently increased the rate of cardiomyogenesis, as indicated by the initial appearance of rhythmically beating cells by Day 6 instead of Day 8. By contrast, co-induction with CHIR plus low levels (3-10 ng/ml) of Bmp4 during Day 0-1 consistently and strongly inhibited cardiomyogenesis. These findings, which demonstrate that cardiomyogenic efficacy is improved by optimizing levels of CHIR-induced growth factors when applied in accord with their sequence of endogenous expression, are consistent with the idea that Nodal (Activin-A) levels toggle the entry of cells into the endodermal or mesodermal lineages, while Bmp levels regulate subsequent allocation into mesodermal cell types.