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Genomic medicine holds great promise for improving health care, but integrating searchable and actionable genetic data into electronic health records (EHRs) remains a challenge. Here we describe Neptune, a system for managing the interaction between a clinical laboratory and an EHR system during the clinical reporting process. We developed Neptune and applied it to two clinical sequencing projects that required report customization, variant reanalysis, and EHR integration. Neptune has been applied for the generation and delivery of over 15,000 clinical genomic reports. This work spans two clinical tests based on targeted gene panels that contain 68 and 153 genes respectively. These projects demanded customizable clinical reports that contained a variety of genetic data types including single-nucleotide variants (SNVs), copy-number variants (CNVs), pharmacogenomics, and polygenic risk scores. Two variant reanalysis activities were also supported, highlighting this important workflow. Methods are needed for delivering structured genetic data to EHRs. This need extends beyond developing data formats to providing infrastructure that manages the reporting process itself. Neptune was successfully applied on two high-throughput clinical sequencing projects to build and deliver clinical reports to EHR systems. The software is open source and available at https://gitlab.com/bcm-hgsc/neptune .

Patients with biallelic mutations in the nuclear-encoded mitochondrial gene C1QBP/p32 have been described with syndromic features and autosomal recessive cardiomyopathy. We describe the clinical course in two siblings who developed cardiomyopathy and ventricular fibrillation in infancy. We provide genomic analysis and clinical-pathologic correlation. Both siblings had profound cardiac failure with ventricular arrhythmia. One child died suddenly. The second sibling survived resuscitation but required extracorporeal cardiopulmonary support and died shortly afterward. On cardiac autopsy, the left ventricle was hypertrophied in both children. Histological examination revealed prominent cardiomyocyte cytoplasmic clearing, and electron microscopy confirmed abnormal mitochondrial structure within cardiomyocytes. DNA sequencing revealed compound heterozygous variants in C1QBP (p.Thr40Asnfs*45 and p.Phe204Leu) in both children. Family segregation analysis demonstrated each variant was inherited from an unaffected, heterozygous parent. Inherited loss of C1QBP/p32 is associated with recessive cardiomyopathy, ventricular fibrillation, and sudden death in early life. Ultrastructural mitochondrial evaluation in the second child was similar to findings in engineered C1qbp-deficient mice. Rapid trio analysis can define rare biallelic variants in genes that may be implicated in sudden death and facilitate medical management and family planning. (184/200).

Background: Cardiomyopathy is a highly heritable disorder that carries a significant risk for heart failure and arrhythmias. Most inherited cardiomyopathies are characterized by variable penetrance and expressivity, which in part arises from additional genetic variation, known as genetic modifiers. Methods and Results: Genomic profiling of human cardiomyopathy cases identified enriched genetic variation in the gene MTCH2. Specifically, a truncating variant was found to be overrepresented in patients with cardiomyopathy compared to controls. MTCH2 encodes a mitochondrial carrier protein that has a role in regulating oxidative phosphorylation. To investigate fundamental mechanisms by which MTCH2 contributes to cardiac and metabolic phenotypes, we generated a knockdown model of the Drosophila MTCH2 ortholog, Mtch. We found that cardiac-specific Mtch reduction in flies produced heart tube dilation and reduced function as well as a shortened life span, documenting a clear role Mtch in the myocardium. Metabolomic profiling demonstrated cardiac deficiency of Mtch lowered the flux of glucose-derived metabolites to the citric acid cycle associated with reduced downstream oxygen consumption and ATP synthesis, causing an energy deficit. We generated a deletion of MTCH2 using gene editing in HEK293 cells. Similar to the fly model, these cells demonstrated reduced oxygen consumption in the presence of glucose, but not fatty acids, and had a higher level of inhibitory phosphorylation of pyruvate dehydrogenase, a critical regulator of glucose metabolism. These data suggest MTCH2 influences the efficiency of glucose oxidation and substrate usage, an important mode of cardiac energy generation, especially in the setting of heart failure. Conclusions: We identified MTCH2 as a modifier of the cardiomyopathy phenotype in humans. Reduction of MTCH2 resulted in impaired cardiac function with reduced oxygen consumption and increased glycolysis in a substrate dependent manner. Since failed hearts are more dependent on glycolysis, these data support that reduction of MTCH2 promotes heart failure and provides a mechanism by which MTCH2 acts as a deleterious genetic modifier in heart failure.

The advancement of precision medicine requires new methods to coordinate and deliver genetic data from heterogeneous sources to physicians and patients. The eMERGE III Network enrolled >25,000 participants from biobank and prospective cohorts of predominantly healthy individuals for clinical genetic testing to determine clinically actionable findings. The network developed protocols linking together the 11 participant collection sites and 2 clinical genetic testing laboratories. DNA capture panels targeting 109 genes were used for testing of DNA and sample collection, data generation, interpretation, reporting, delivery, and storage were each harmonized. A compliant and secure network enabled ongoing review and reconciliation of clinical interpretations, while maintaining communication and data sharing between clinicians and investigators. A total of 202 individuals had positive diagnostic findings relevant to the indication for testing and 1,294 had additional/secondary findings of medical significance deemed to be returnable, establishing data return rates for other testing endeavors. This study accomplished integration of structured genomic results into multiple electronic health record (EHR) systems, setting the stage for clinical decision support to enable genomic medicine. Further, the established processes enable different sequencing sites to harmonize technical and interpretive aspects of sequencing tests, a critical achievement toward global standardization of genomic testing. The eMERGE protocols and tools are available for widespread dissemination.

Importance Postmortem genetic testing of young individuals with sudden death has previously identified pathogenic gene variants. However, prior studies primarily considered highly penetrant monogenic variants, often without detailed decedent and family clinical information. Objective To assess genotype and phenotype risk in a diverse cohort of young decedents with sudden death and their families. Design, Setting, and Participants Pathological and whole-genome sequence analysis was conducted in a cohort referred from a national network of medical examiners. Cases were accrued prospectively from May 2015 to March 2019 across 24 US states. Analysis began September 2016 and ended November 2020. Exposures Evaluation of autopsy and clinical data integrated with whole-genome sequence data and family member evaluation. Results A total of 103 decedents (mean [SD] age at death, 23.7 [11.9] years; age range, 1-44 years), their surviving family members, and 140 sex- and genetic ancestry–matched controls were analyzed. Among 103 decedents, autopsy and clinical data review categorized 36 decedents with postmortem diagnoses, 23 decedents with findings of uncertain significance, and 44 with sudden unexplained death. Pathogenic/likely pathogenic (P/LP) genetic variants in arrhythmia or cardiomyopathy genes were identified in 13 decedents (12.6%). A multivariable analysis including decedent phenotype, ancestry, and sex demonstrated that younger decedents had a higher burden of P/LP variants and select variants of uncertain significance (effect size, −1.64;P = .001). These select, curated variants of uncertain significance in cardiac genes were more common in decedents than controls (83 of 103 decedents [86%] vs 100 of 140 controls [71%];P = .005), and decedents harbored more rare cardiac variants than controls (2.3 variants per individual vs 1.8 in controls;P = .006). Genetic testing of 31 parent-decedent trios and 14 parent-decedent dyads revealed 8 transmitted P/LP variants and 1 de novo P/LP variant. Incomplete penetrance was present in 6 of 8 parents who transmitted a P/LP variant. Conclusions and Relevance Whole-genome sequencing effectively identified P/LP variants in cases of sudden death in young individuals, implicating both arrhythmia and cardiomyopathy genes. Genomic analyses and familial phenotype association suggest potentially additive, oligogenic risk mechanisms for sudden death in this cohort.

AIMS : Our objective was to better understand the genetic bases of dilated cardiomyopathy (DCM), a leading cause of systolic heart failure. METHODS AND RESULTS : We conducted the largest genome-wide association study performed so far in DCM, with 2719 cases and 4440 controls in the discovery population. We identified and replicated two new DCM-associated loci on chromosome 3p25.1 [lead single-nucleotide polymorphism (SNP) rs62232870, P = 8.7 × 10(−11) and 7.7 × 10(−4) in the discovery and replication steps, respectively] and chromosome 22q11.23 (lead SNP rs7284877, P = 3.3 × 10(−8) and 1.4 × 10(−3) in the discovery and replication steps, respectively), while confirming two previously identified DCM loci on chromosomes 10 and 1, BAG3 and HSPB7. A genetic risk score constructed from the number of risk alleles at these four DCM loci revealed a 3-fold increased risk of DCM for individuals with 8 risk alleles compared to individuals with 5 risk alleles (median of the referral population). In silico annotation and functional 4C-sequencing analyses on iPSC-derived cardiomyocytes identify SLC6A6 as the most likely DCM gene at the 3p25.1 locus. This gene encodes a taurine transporter whose involvement in myocardial dysfunction and DCM is supported by numerous observations in humans and animals. At the 22q11.23 locus, in silico and data mining annotations, and to a lesser extent functional analysis, strongly suggest SMARCB1 as the candidate culprit gene. CONCLUSION : This study provides a better understanding of the genetic architecture of DCM and sheds light on novel biological pathways underlying heart failure.

Background Inherited cardiomyopathies display variable penetrance and expression, and a component of phenotypic variation is genetically determined. To evaluate the genetic contribution to this variable expression, we compared protein coding variation in the genomes of those with hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Methods and Results Nonsynonymous single‐nucleotide variants (nsSNVs) were ascertained using whole genome sequencing from familial cases of HCM (n=56) or DCM (n=70) and correlated with echocardiographic information. Focusing on nsSNVs in 102 genes linked to inherited cardiomyopathies, we correlated the number of nsSNVs per person with left ventricular measurements. Principal component analysis and generalized linear models were applied to identify the probability of cardiomyopathy type as it related to the number of nsSNVs in cardiomyopathy genes. The probability of having DCM significantly increased as the number of cardiomyopathy gene nsSNVs per person increased. The increase in nsSNVs in cardiomyopathy genes significantly associated with reduced left ventricular ejection fraction and increased left ventricular diameter for individuals carrying a DCM diagnosis, but not for those with HCM. Resampling was used to identify genes with aberrant cumulative allele frequencies, identifying potential modifier genes for cardiomyopathy. Conclusions Participants with DCM had more nsSNVs per person in cardiomyopathy genes than participants with HCM. The nsSNV burden in cardiomyopathy genes did not correlate with the probability or manifestation of left ventricular measures in HCM. These findings support the concept that increased variation in cardiomyopathy genes creates a genetic background that predisposes to DCM and increased disease severity.

Background: Inherited cardiomyopathy associates with a range of phenotypes, mediated by genetic and nongenetic factors. Noninherited cardiomyopathy also displays varying progression and outcomes. Expression of cardiomyopathy genes is under the regulatory control of promoters and enhancers, and human genetic variation in promoters and enhancers may contribute to this variability. Methods: We superimposed epigenomic profiling from hearts and cardiomyocytes, including promoter-capture chromatin conformation information, to identify enhancers for 2 cardiomyopathy genes, MYH7 and LMNA . Enhancer function was validated in human cardiomyocytes derived from induced pluripotent stem cells. We also conducted a genome-wide search to ascertain genomic variation in enhancers positioned to alter cardiac expression and correlated one of these variants to cardiomyopathy progression using biobank data. Results: Multiple enhancers were identified and validated for LMNA and MYH7 , including a key enhancer that regulates the switch from MYH6 expression to MYH7 expression. Deletion of this enhancer resulted in a dose-dependent increase in MYH6 and faster contractile rate in engineered heart tissues. We searched for genomic variation in enhancer sequences across the genome, with a focus on nucleotide changes that create or interrupt transcription factor binding sites. The sequence variant, rs875908, disrupts a T-Box Transcription Factor 5 binding motif and maps to an enhancer region 2 kilobases from the transcriptional start site of MYH7. Gene editing to remove the enhancer that harbors this variant markedly reduced MYH7 expression in human cardiomyocytes. Using biobank-derived data, rs875908 associated with longitudinal echocardiographic features of cardiomyopathy. Conclusions: Enhancers regulate cardiomyopathy gene expression, and genomic variation within these enhancer regions associates with cardiomyopathic progression over time. This integrated approach identified noncoding modifiers of cardiomyopathy and is applicable to other cardiac genes.

Introduction: Inherited cardiomyopathy is caused by mutations in more than 100 genes. A well-recognized clinical feature of genetic cardiomyopathy is varying phenotypic expression. Even with identical primary mutations, there is a range of clinical outcomes. Genetic variants in protein coding regions have been shown to alter the phenotypic expression of primary cardiomyopathy-causing mutations. However, the contribution of noncoding variation has been less well studied. Methods and Results: We used an integrative analysis of >20 publicly-available heart enhancer function and enhancer target datasets to identify genomic regions predicted to regulate the cardiomyopathy genes, MYH7 and LMNA . We identified two candidate enhancer clusters around the MYH7 gene and three clusters around the LMNA gene. We tested enhancers in these clusters using reporter assays and CRISPr-mediated deletion in human cardiomyocytes derived from induced pluripotent stem cells (iCMs). We identified a super enhancer upstream of MYH7 that is necessary for high MYH7 expression in iCMs. These regulatory regions contained sequence variants within transcription factor binding sites that altered enhancer function. We created an informatic pipeline that extended this strategy genomewide to identify an additional enhancer modifying variant upstream of MYH7 . This variant disrupts a transcription factor binding site upstream of MYH7 and limits MYH7 upregulation. We extended these analyses by examining clinical correlates, finding that this variant correlated with a more dilated left ventricle over time in patients with cardiomyopathy. Conclusions: We identified two enhancer regions important for MYH7 expression in iCMs. These enhancer regions may be utilized to induce MYH7 during human development and heart failure. MYH7 changes in heart failure have been linked to cardiomyopathy phenotypes. The variant upstream of MYH7 likely alters these changes and results in a more severe phenotype. These findings demonstrate that noncoding variants have clinical utility and targeted assessment of noncoding modifiers may become integrated into clinical care.

Introduction: Genetic testing after sudden death in the young can identify pathogenic cardiac gene variants. Hypothesis: Genomic methods, coupled with phenotype evaluation, reveal non-Mendalian risks. Methods: We conducted clinical analysis and whole genome sequencing on 103 decedents aged 1-40 (mean age at death 23.7 years) accrued prospectively from 2015 to 2019 across 22 states. Postmortem pathological findings were classified as: known cardiac disorders, findings of uncertain significance (FUS), or sudden unexplained death (SUD, indicating no postmortem pathological diagnosis). Parental DNA and clinical data were obtained where possible. Variants were classified by an independent clinical genetic laboratory. Results: Among the 103 decedents, 34 had a postmortem clinical diagnosis, 23 had FUS, and 46 were classified as SUD. Pathogenic/likely pathogenic (P/LP) variants in arrhythmia or cardiomyopathy genes were identified in 17 (16.5%) decedents. The distribution of P/LP variants was not associated with age at death (OR 1.01 [0.97, 1.05], p=0.54); however, a multivariable analysis including decedent phenotype, ancestry and sex demonstrated that younger decedents had a higher burden of curated P/LP/VUS variants (effect size -1.5, p=0.0019). DNA from 31 parent-decedent trios and 14 parent-decedent dyads revealed 9 transmitted P/LP variants and 1 de novo P/LP variant. More than half of parents transmitting a P/LP variant (5/9) did not have clinical findings associated with the genotype. Conclusions: Whole genome sequencing effectively revealed P/LP variants in cases of sudden death in the young, implicating both arrhythmia and cardiomyopathy genes. In addition, both genotype and phenotype analyses suggest additional non-Mendelian risk mechanisms.

Background: The failing heart is characterized by changes in gene expression. However, the regulatory regions of the genome that drive these gene expression changes have not been well defined in human hearts. Methods: To define genome-wide enhancer and promoter use in heart failure, cap analysis of gene expression sequencing was applied to 3 healthy and 4 failed human hearts to identify promoter and enhancer regions used in left ventricles. Healthy hearts were derived from donors unused for transplantation and failed hearts were obtained as discarded tissue after transplantation. Results: Cap analysis of gene expression sequencing identified a combined potential for ≈23 000 promoters and ≈5000 enhancers active in human left ventricles. Of these, 17 000 promoters and 1800 enhancers had additional support for their regulatory function. Comparing promoter usage between healthy and failed hearts highlighted promoter shifts which altered aminoterminal protein sequences. Enhancer usage between healthy and failed hearts identified a majority of differentially used heart failure enhancers were intronic and primarily localized within the first intron, revealing this position as a common feature associated with tissue-specific gene expression changes in the heart. Conclusions: This data set defines the dynamic genomic regulatory landscape underlying heart failure and serves as an important resource for understanding genetic contributions to cardiac dysfunction. Additionally, regulatory changes contributing to heart failure are attractive therapeutic targets for controlling ventricular remodeling and clinical progression.

BackgroundAfter sudden cardiac death in people aged Methods and ResultsWe surveyed medical examiner offices to determine which tools were used to assess heart weight norms. The survey determined that there was no gold standard for cardiomegaly (52 centers reported 22 different methods). We used a collection of heart weight data from sudden deaths in the Northwestern Sudden Death Collaboration (NSDC) to test the 22 methods. We found that the methods reported in our survey had little consistency: they classified between 18% and 81% of NSDC hearts with cardiomegaly. Therefore, we obtained biometric and postmortem data from a reference population of 3398 decedents aged ConclusionsMedical examiner offices use a variety of tools to classify cardiomegaly. These approaches produce inconsistent results, and many overinterpret cardiomegaly. We recommend the model proposed to classify postmortem cardiomegaly in cases of sudden cardiac death in young people.

Background: Cardiomyopathy is a highly heritable disorder that carries a significant risk for heart failure and arrhythmias. The onset, severity, and progression of cardiomyopathy is influenced by genetic variation, with the most common form of inheritance in familial cases being autosomal dominant. All inherited cardiomyopathies are characterized by variable penetrance and expressivity, which in part arises from additional genetic variation, known as genetic modifiers. Methods and Results: Broad genomic profiling of human cardiomyopathy cases identified enriched genetic variation in the gene MTCH2. Specifically, a loss of function variant was found to be enriched in patients with cardiomyopathy. MTCH2 single nucleotide polymorphisms have also been linked to obesity, underscoring a critical role for MTCH2 in metabolic regulation. MTCH2 encodes a mitochondrial carrier protein that has a role in regulating oxidative phosphorylation. In order to investigate fundamental mechanisms by which MTCH2 contributes to cardiac and metabolic phenotypes, we generated a knockdown model of the Drosophila MTCH2 ortholog, Mtch. This knockdown model mimics what is seen in human carriers with the heterozygous loss of function allele. In the Drosophila model, Mtch RNA was reduced by approximately half. We found that cardiac-specific Mtch deficiency in flies produced heart tube dilated and reduced function as well as a shortened life span, documenting a clear role for cardiac Mtch. Cardiac deficiency of Mtch increased circulating lactate levels in flies. Oxygen consumption was reduced in cardiac Mtch deficiency flies in the presence of glucose, but not palmitate. Thus, loss of Mtch2 alters oxygen consumption in a substrate dependent manner. Conclusions: We identified MTCH2 as a modifier of the cardiomyopathy phenotype in humans. Reduction of Mtch in flies resulted in impaired cardiac function and reduced oxygen consumption under certain metabolic condition. As failed hearts are more dependent on glycolysis, these data support that reduction of MTCH2 promotes heart failure and provides a mechanism by which MTCH2 acts as a deleterious genetic modifier in heart failure.

Background: Cardiomyopathy and arrhythmias are under significant genetic influence. Here, we studied a family with dilated cardiomyopathy and associated conduction system disease in whom prior clinical cardiac gene panel testing was unrevealing. Methods: Whole-genome sequencing and induced pluripotent stem cells were used to examine a family with dilated cardiomyopathy and atrial and ventricular arrhythmias. We also characterized a mouse model with heterozygous and homozygous deletion of Mybphl . Results: Whole-genome sequencing identified a premature stop codon, R255X, in the MYBPHL gene encoding MyBP-HL (myosin-binding protein-H like), a novel member of the myosin-binding protein family. MYBPHL was found to have high atrial expression with low ventricular expression. We determined that MyBP-HL protein was myofilament associated in the atria, and truncated MyBP-HL protein failed to incorporate into the myofilament. Human cell modeling demonstrated reduced expression from the mutant MYBPHL allele. Echocardiography of Mybphl heterozygous and null mouse hearts exhibited a 36% reduction in fractional shortening and an increased diastolic ventricular chamber size. Atria weight normalized to total heart weight was significantly increased in Mybphl heterozygous and null mice. Using a reporter system, we detected robust expression of Mybphl in the atria, and in discrete puncta throughout the right ventricular wall and septum, as well. Telemetric electrocardiogram recordings in Mybphl mice revealed cardiac conduction system abnormalities with aberrant atrioventricular conduction and an increased rate of arrhythmia in heterozygous and null mice. Conclusions: The findings of reduced ventricular function and conduction system defects in Mybphl mice support that MYBPHL truncations may increase risk for human arrhythmias and cardiomyopathy.

Background Genome sequencing coupled with electronic heath record data can uncover medically important genetic variation. Interpretation of rare genetic variation and its role in mediating cardiovascular phenotypes is confounded by variants of uncertain significance. Methods and Results We analyzed the whole genome sequence of 900 racially and ethnically diverse biobank participants selected from a single US center. Participants were equally divided among European, African, Hispanic, and mixed races/ethnicities. We evaluated the American College of Medical Genetics and Genomics medically actionable list of 59 genes, focusing on the cardiac genes. Variation was interpreted using the most recent reports in ClinVar, a database of medically relevant human variation. We identified 19 individuals with pathogenic or likely pathogenic variants in cardiac actionable genes (2%) and found evidence of related clinical correlates in the electronic health record. Participants of African ancestry, compared with those of European ancestry, had more variants of uncertain significance in the medically actionable genes including the 30 cardiac actionable genes, even when normalized to total variant count per person. Longitudinal measures of left ventricle size from ≈400 biobank participants (1723 patient‐years) were correlated with genetic findings. The presence of ≥1 uncertain variant in the actionable cardiac genes and a cardiomyopathy diagnosis correlated with increased left ventricular internal diameter in diastole and in systole. In particular, MYBPC 3 was identified as a gene with excess variants of uncertain significance. Conclusions These data indicate that a subset of uncertain genetic variants may confer risk and should not be considered benign.

Background Randomised controlled trials (RCTs) of vitamin D to prevent COPD exacerbations have yielded conflicting results. Individual participant data meta-analysis could identify factors that explain this variation. Methods PubMed, Embase, the Cochrane Central Register of Controlled Trials and Web of Science were searched from inception up to and including 5 October 2017 to identify RCTs of vitamin D supplementation in patients with COPD that reported incidence of acute exacerbations. Individual participant data meta-analysis was performed using fixed effects models adjusting for age, sex, Global Initiative for Chronic Obstructive Lung Disease spirometric grade and trial. Results Four eligible RCTs (total 560 participants) were identified; individual participant data were obtained for 469/472 (99.4%) participants in three RCTs. Supplementation did not influence overall rate of moderate/severe COPD exacerbations (adjusted incidence rate ratio (aIRR) 0.94, 95% CI 0.78 to 1.13). Prespecified subgroup analysis revealed that protective effects were seen in participants with baseline 25-hydroxyvitamin D levels Conclusions Vitamin D supplementation safely and substantially reduced the rate of moderate/severe COPD exacerbations in patients with baseline 25-hydroxyvitamin D levels Trial registration number CRD42014013953.

Importance Cardiac fibrosis is exceedingly rare in young adults. Identification of genetic variants that cause early-onset cardiomyopathy may inform novel biological pathways. Experimental models and a single case report have linked genetic deficiency of plasminogen activator inhibitor-1 (PAI-1), a downstream target of cardiac transforming growth factor β, with cardiac fibrosis. Objective To perform detailed cardiovascular phenotyping and genotyping in young adults from an Amish family with a frameshift variant (c.699_700dupTA) inSERPINE1, the gene that codes for PAI-1. Design, Setting, and Participants This observational study included participants from 3 related nuclear families from an Amish community in the primary analysis and participants from the extended family in the secondary analysis. Participants were recruited from May 2015 to December 2016, and analysis took place from June 2015 to June 2020. Main Outcomes and Measures (1) Multimodality cardiovascular imaging (transthoracic echocardiography and cardiac magnetic resonance imaging), (2) whole-exome sequencing, and (3) induced pluripotent stem cell–derived cardiomyocytes. Results Among 17 participants included in the primary analysis, the mean (interquartile range) age was 23.7 (20.9-29.9) years and 9 individuals (52.9%) were confirmed to be homozygous for theSERPINE1c.699_700dupTA variant. Late gadolinium enhancement was present in 6 of 9 homozygous participants (67%) with absolute PAI-1 deficiency vs 0 of 8 in the control group (P = .001). Late gadolinium enhancement patterns tended to be dense and linear, usually subepicardial but also midmyocardial and transmural with noncoronary distributions. Targeted whole-exome sequencing analysis identified that homozygosity for c.699_700dupTASERPINE1was the only shared pathogenic variant or variant of uncertain significance after examination of cardiomyopathy genes among those with late gadolinium enhancement. Induced pluripotent stem cell–derived cardiomyocytes from participants homozygous for theSERPINE1c.699_700dupTA variant exhibited susceptibility to cardiomyocyte injury in response to angiotensin II (increased transforming growth factor β1 secretion and release of lactate dehydrogenase) compared with control induced pluripotent stem cell–derived cardiomyocytes. In a secondary analysis based on echocardiography in 155 individuals across 3 generations in the extended family, no difference in global longitudinal strain was observed in carriers for theSERPINE1c.699_700dupTA variant compared with wild-type participants, supporting an autosomal recessive inheritance pattern. Conclusions and Relevance In this study, a highly penetrant, autosomal recessive, cardiac fibrosis phenotype among young adults with homozygous frameshift variant forSERPINE1was identified, suggesting an optimal range of PAI-1 levels are needed for cardiac homeostasis.

Dilated cardiomyopathy is under significant genetic influence. Using whole-genome sequencing, we found a premature stop variant (R255X) in the MYBPHL gene in a family with DCM and conduction system disease. A Mybphl null mouse model revealed systolic dysfunction with atrial and ventricular conduction system (VCS) abnormalities. We found MyBP-HL protein highly expressed in both human and mouse atria and in a subset of ventricular cardiomyocytes. We hypothesize that MyBP-HL regulates VCS function and loss of MyBP-HL causes ventricular arrhythmia and cardiac dysfunction. We now examined hearts and isolated VCMs from Mybphl WT, het, and null mice using immunofluorescence microscopy (IFM). Clusters of MyBP-HL+ ventricular cardiomyocytes were evident in WT hearts (~1/200,000), with only 10% as many MyBP-HL+ cardiomyocytes in het samples. In WT hearts, MyBP-HL+ cells localized in the right ventricular free wall, with significantly fewer MyBP-HL+ cells in the right ventricular free wall in het hearts. The VCS marker contactin-2 (Cntn2) was used to assess MyBP-HL co-localization in the VCS. MyBP-HL co-localized with Cntn2+ cardiomyocytes in the transition zone between the atria and ventricle near the AV node, as well as in a subset of Cntn2+ Purkinje fibers. MyBP-HL+ ventricular cardiomyocytes were also found outside the VCS, suggesting other roles for those cells in regulating ventricular function. To discern MyBP-HL myofilament localization, we used super-resolution structured illumination microscopy on atrial cardiomyocytes. MyBP-HL co-localized with cMyBP-C in the C-zone of the A-band but also occupied space in the inner portion of the A-band near the M-line. This localization was not altered in het mice; however, the ratio of MyBP-HL in the inner portion of the A-band was diminished in het mice compared to WT. This suggests that MyBP-HL may bind the light meromyosin coiled-coil tail that originates from the M-line. Following the discovery that loss of MyBP-HL is associated with DCM and arrhythmia, we identified that MyBP-HL associates with the VCS and reduced MyBP-HL levels reduce the amount of MyBP-HL positive VCMs. These data suggest that loss of MyBP-HL may impair the development and function of the VCS, resulting in arrhythmias.

IMPORTANCE: The genetic variant MYBPC3(Δ25bp) occurs in 4% of South Asian descendants, with an estimated 100 million carriers worldwide. MYBPC3 (Δ25bp) has been linked to cardiomyopathy and heart failure. However, the high prevalence of MYBPC3(Δ25bp) suggests that other stressors act in concert with MYBPC3(Δ25bp). OBJECTIVE: To determine whether there are additional genetic factors that contribute to the cardiomyopathic expression of MYBPC3(Δ25bp). DESIGN, SETTING, ANDPARTICIPANTS: South Asian individuals living in the United States were screened for MYBPC3(Δ25bp), and a subgroup was clinically evaluated using electrocardiograms and echocardiograms at Loyola University, Chicago, Illinois, between January 2015 and July 2016. MAIN OUTCOMES AND MEASURES: Next-generation sequencing of 174 cardiovascular disease genes was applied to identify additional modifying gene mutations and correlate genotype-phenotype parameters. Cardiomyocytes derived from human-induced pluripotent stem cells were established and examined to assess the role of MYBPC3(Δ25bp). RESULTS: In this genotype-phenotype study, individuals of South Asian descent living in the United States from both sexes (36.23% female) with a mean population age of 48.92 years (range, 18-84 years) were recruited. Genetic screening of 2401 US South Asian individuals found an MYBPC3(Δ25bp)carrier frequency of 6%. A higher frequency of missense TTN variation was found in MYBPC3(Δ25bp) carriers compared with noncarriers, identifying distinct genetic backgrounds within the MYBPC3(Δ25bp) carrier group. Strikingly, 9.6% of MYBPC3(Δ25bp) carriers also had a novel MYBPC3 variant, D389V. Family studies documented D389V was in tandem on the same allele as MYBPC3(Δ25bp), and D389V was only seen in the presence of MYBPC3(Δ25bp). In contrast to MYBPC3(Δ25bp), MYBPC3(Δ25bp/D389V) was associated with hyperdynamic left ventricular performance (mean [SEM] left ventricular ejection fraction, 66.7 [0.7%]; left ventricular fractional shortening, 36.6 [0.6%]; P

Cardiovascular disease is a major health concern affecting over 80,000,000 people in the U.S. alone. Heart failure, cardiomyopathy, heart rhythm disorders, atherosclerosis and aneurysm formation have significant heritable contribution. Supported by familial aggregation and twin studies, these cardiovascular diseases are influenced by genetic variation. Family-based linkage studies and population-based genome-wide association studies (GWAS) have each identified genes and variants important for the pathogenesis of cardiovascular disease. The advent of next generation sequencing has ushered in a new era in the genetic diagnosis of cardiovascular disease, and this is especially evident when considering cardiomyopathy, a leading cause of heart failure. Cardiomyopathy is a genetically heterogeneous disorder characterized by morphologically abnormal heart with abnormal function. Genetic testing for cardiomyopathy employs gene panels, and these panels assess more than 50 genes simultaneously. Despite the large size of these panels, the sensitivity for detecting the primary genetic defect is still only approximately 50%. Recently, there has been a shift towards applying broader exome and/or genome sequencing to interrogate more of the genome to provide a genetic diagnosis for cardiomyopathy. Genetic mutations in cardiomyopathy offer the capacity to predict clinical outcome, including arrhythmia risk, and genetic diagnosis often provides an early window in which to institute therapy. This discussion is an overview as to how genomic data is shaping the current understanding and treatment of cardiovascular disease.

In this issue, Bierzynska et al. report the results of analyzing a cohort of children with steroid-resistant nephrotic syndrome (SRNS) of childhood, correlating genetic studies with clinical outcomes. This approach has the potential to advance both our research into the causes and treatments of childhood SRNS and our ability to stratify patients into groups that are likely to be responsive to specific treatments. Here, we discuss some of the strengths and limitations of this report.

We thank Iascone et al for their thoughtful comments on our survey of potentially pathological or reported pathological genetic variation found in the 1000 Genomes database. …