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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.

Background: \ud Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene.\ud \ud Objectives: \ud This study sought to test the association between the rs9349379 genotype and SCAD.\ud \ud Methods: \ud Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD.\ud \ud Results: \ud The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence.\ud \ud Conclusions: \ud The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD.

Background: Hypoplastic left heart syndrome (HLHS) with risk of poor outcome has been linked to MYH6 variants, implicating overlap in genetic etiologies of structural and myopathic heart disease. Methods: Whole genome sequencing was performed in 197 probands with HLHS, 43 family members, and 813 controls. Data were filtered for rare, segregating variants in 3 index families comprised of an HLHS proband and relative(s) with cardiomyopathy. Whole genome sequencing data from cases and controls were compared for rare variant burden across 56 cardiomyopathy genes utilizing a weighted burden test approach, accounting for multiple testing using a Bonferroni correction. Results: A pathogenic MYBPC3 nonsense variant was identified in the first proband who underwent cardiac transplantation for diastolic heart failure, her father with left ventricular noncompaction, and 2 fourth-degree relatives with hypertrophic cardiomyopathy. A likely pathogenic RYR2 missense variant was identified in the second proband, a second-degree relative with aortic dilation, and a fourth-degree relative with dilated cardiomyopathy. A pathogenic RYR2 exon 3 in-frame deletion was identified in the third proband diagnosed with catecholaminergic polymorphic ventricular tachycardia and his father with left ventricular noncompaction and catecholaminergic polymorphic ventricular tachycardia. To further investigate HLHS-cardiomyopathy gene associations in cases versus controls, rare variant burden testing of 56 genes revealed enrichment in MYH6 ( P =0.000068). Rare, predicted-damaging MYH6 variants were identified in 10% of probands in our cohort—4 with familial congenital heart disease, 4 with compound heterozygosity (3 with systolic ventricular dysfunction), and 4 with MYH6 – FLNC synergistic heterozygosity. Conclusions: Whole genome sequencing in multiplex families, proband-parent trios, and case-control cohorts revealed defects in cardiomyopathy-associated genes in patients with HLHS, which may portend impaired functional reserve of the single-ventricle circulation.

Idiopathic restrictive cardiomyopathy (IRC) is a rare condition characterized by reduced ventricular compliance. Children with IRC have poor outcomes with most patients proceeding to cardiac transplantation. We sought to analyze our institutional experience and assess contemporary outcomes for children with IRC. We reviewed the medical record for patients (21 years old) evaluated for a primary diagnosis of IRC between 1975 and 2013 at our institution. Demographic, clinical, echocardiographic, and catheterization data were abstracted. The patients were divided into 2 groups comprising a historical cohort (HC) (diagnosis: 1975 to 1993, n = 8) and a contemporary cohort (CC) (diagnosis: 1994 to 2013, n = 12). Twenty children were identified with IRC (mean age at presentation 9.7 ± 6.5 years, 55% female). Mean length of follow-up was 6.5 ± 8.4 years (range 0.1 to 35.6 years). In the CC, 7 of 12 patients (58%) progressed to cardiac transplantation (mean age of 9 ± 4 years at transplant, mean interval from diagnosis of IRC: 1.5 ± 0.9 years). Overall survival was improved significantly in the CC compared with the HC (80% vs. 38%, p = 0.02), but transplantation free survival was no different between the CC and HC over 5 years (38% vs 38%, p = 0.65). In the CC, elevation of mitral valve Doppler E/e' ratio on echocardiography was associated with increased mortality (p = 0.01). In conclusion, IRC continues has a poor prognosis. Early referral for transplantation was associated with improved overall survival in the modern era. Patients with markedly elevated E/e' ratio may have increased risk of death.

Background In patients with bicuspid aortic valve (BAV), complications including progressive aortic stenosis and aortic dilatation develop over time. The morphology of cusp fusion is one of the determinants of the type and severity of these complications. We present the association of morphology of cusp fusion in BAV patients with distinctive genetic syndromes. Methods The Mayo Clinic echocardiography database was retrospectively reviewed to identify patients (age ≤ 22 years) diagnosed with BAV from 1990 to 2016. Cusp fusion morphology was determined from the echocardiographic studies, while coexisting cardiac defects and genetic syndromes were determined from chart review. Results A total of 1,037 patients with BAV were identified: 550 (53%) had an isolated BAV, 299 (29%) had BAV and a coexisting congenital heart defect, and 188 (18%) had BAV and a coexisting genetic syndrome or disorder. There were no differences in distribution of morphology across the three groups. However, right-noncoronary (RN) cusp fusion was the predominant morphology associated with Down syndrome ( P = .002) and right-left (RL) cusp fusion was the predominant morphology associated with Turner syndrome ( P = .02), DiGeorge syndrome ( P = .02), and Shone syndrome ( P = .0007), when compared with valve morphology in patients with isolated BAV. Isolated BAV patients with RN cusp fusion had larger ascending aorta diameter ( P = .001) and higher number of patients with ≥ moderate aortic regurgitation ( P = .02), while those with RL cusp fusion had larger sinus of Valsalva diameter ( P = .0006). Conclusions Morphological subtypes of BAV are associated with different genetic syndromes, suggesting distinct perturbations of developmental pathways in aortic valve malformation.

Ebstein anomaly of the tricuspid valve (EA) can be associated with left ventricular non-compaction (LVNC), a rare congenital cardiomyopathy. We report a 2 year-old female with EA and severe tricuspid regurgitation, LVNC, pulmonary hypertension, and chronic biventricular systolic heart failure, who died during evaluation for cardiac transplantation. Gene panel testing revealed a heterozygous de novo missense mutation in TPM1, which encodes the cardiac sarcomeric thin filament protein α-tropomyosin. The c.475G>A variant results in a p.Asp159Asn substitution, altering a highly conserved residue predicted to be damaging to protein structure and function. TPM1 is the second gene linked to EA with LVNC in humans, implicating overlap in the molecular basis of structural and myopathic heart disease. © 2016 Wiley Periodicals, Inc.

We previously reported that the cardiomyocyte-specific leucine-rich repeat containing protein (LRRC)10 has critical functions in the mammalian heart. In the present study, we tested the role of LRRC10 in the response of the heart to biomechanical stress by performing transverse aortic constriction on Lrrc10-null ( Lrrc10−/−) mice. Mild pressure overload induced severe cardiac dysfunction and ventricular dilation in Lrrc10−/−mice compared with control mice. In addition to dilation and cardiomyopathy, Lrrc10−/−mice showed a pronounced increase in heart weight with pressure overload stimulation and a more dramatic loss of cardiac ventricular performance, collectively suggesting that the absence of LRRC10 renders the heart more disease prone with greater hypertrophy and structural remodeling, although rates of cardiac fibrosis and myocyte dropout were not different from control mice. Lrrc10−/−cardiomyocytes also exhibited reduced contractility in response to β-adrenergic stimulation, consistent with loss of cardiac ventricular performance after pressure overload. We have previously shown that LRRC10 interacts with actin in the heart. Here, we show that His150of LRRC10 was required for an interaction with actin, and this interaction was reduced after pressure overload, suggesting an integral role for LRRC10 in the response of the heart to mechanical stress. Importantly, these experiments demonstrated that LRRC10 is required to maintain cardiac performance in response to pressure overload and suggest that dysregulated expression or mutation of LRRC10 may greatly sensitize human patients to more severe cardiac disease in conditions such as chronic hypertension or aortic stenosis.

IMPORTANCE: Spontaneous coronary artery dissection (SCAD), an idiopathic disorder that predominantly affects young to middle-aged women, has emerged as an important cause of acute coronary syndrome, myocardial infarction, and sudden cardiac death. OBJECTIVE: To identify common single-nucleotide variants (SNVs) associated with SCAD susceptibility. DESIGN, SETTING, AND PARTICIPANTS: This single-center genome-wide association study examined approximately 5 million genotyped and imputed SNVs and subsequent SNV-targeted replication analysis results in individuals enrolled in the Mayo Clinic SCAD registry from August 30, 2011, to August 2, 2018. Data analysis was performed from June 21, 2017, to December 30, 2019. MAIN OUTCOMES AND MEASURES: Genetic loci and positional candidate genes associated with SCAD. RESULTS: This study included 484 white women with SCAD (mean [SD] age, 46.6 [9.2] years) and 1477 white female controls in the discovery cohort (mean [SD] age, 64.0 [14.5] years) and 183 white women with SCAD (mean [SD] age, 47.1 [9.9] years) and 340 white female controls in the replication cohort (mean [SD] age, 51.0 [15.3] years). Associations with SCAD risk reached genome-wide significance at 3 loci (1q21.3 [OR, 1.78; 95% CI, 1.51-2.09; P = 2.63 × 10(−12)], 6p24.1 [OR, 1.77; 95% CI, 1.51-2.09; P = 7.09 × 10(−12)], and 12q13.3 [OR, 1.67; 95% CI, 1.42-1.97; P = 3.62 × 10(−10)]), and 7 loci had evidence suggestive of an association (1q24.2 [OR, 2.10; 95% CI, 1.58-2.79; P = 2.88 × 10(−7)], 3q22.3 [OR, 1.47; 95% CI, 1.26-1.71; P = 6.65 × 10(−7)], 4q34.3 [OR, 1.84; 95% CI, 1.44-2.35; P = 9.80 × 10(−7)], 8q24.3 [OR, 2.57; 95% CI, 1.76-3.75; P = 9.65 × 10(−7)], 15q21.1 [OR, 1.75; 95% CI, 1.40-2.18; P = 7.23 × 10(−7)], 16q24.1 [OR, 1.91; 95% CI, 1.49-2.44; P = 2.56 × 10(−7)], and 21q22.11 [OR, 2.11; 95% CI, 1.59-2.82; P = 3.12 × 10(−7)]) after adjusting for the top 5 principal components. Associations were validated for 5 of the 10 risk alleles in the replication cohort. In a meta-analysis of the discovery and replication cohorts, associations for the 5 SNVs were significant, with relatively large effect sizes (1q21.3 [OR, 1.77; 95% CI, 1.54-2.03; P = 3.26 × 10(−16)], 6p24.1 [OR, 1.71; 95% CI, 1.49-1.97; P = 4.59 × 10(−14)], 12q13.3 [OR, 1.69; 95% CI, 1.47-1.94; P = 1.42 × 10(−13)], 15q21.1 [OR, 1.79; 95% CI, 1.48-2.17; P = 2.12 × 10(−9)], and 21q22.11 [OR, 2.18; 95% CI, 1.70-2.81; P = 1.09 × 10(−9)]). Each index SNV was within or near a gene highly expressed in arterial tissue and previously linked to SCAD (PHACTR1) and/or other vascular disorders (LRP1, LINC00310, and FBN1). CONCLUSIONS AND RELEVANCE: This study revealed 5 replicated risk loci and positional candidate genes for SCAD, most of which are associated with extracoronary arteriopathies. Moreover, the alternate alleles of 3 SNVs have been previously associated with atherosclerotic coronary artery disease, further implicating allelic susceptibility to coronary artery atherosclerosis vs dissection.

The increased workload on single right ventricle (sRV) leads to increased risk of Fontan failure due to ventricular dysfunction. Conventional heart failure therapy has mixed results. This has led to increased interest in seeking alternative therapeutic strategies to improve ventricular function

Obstructive left-sided congenital heart lesions exhibit familial clustering, and familial echocardiographic screening for bicuspid aortic valve has become standard practice. Hypoplastic left heart syndrome (HLHS) is a severe left-sided obstructive lesion; however, familial screening is not universally recommended. The purpose of this study was to define the incidence of cardiovascular malformations (CVMs) in first-degree relatives of HLHS probands. First-degree relatives were screened for CVM by transthoracic echocardiography. Screening was completed in 152 family members (97 parents and 55 siblings) of 52 probands. Of these, 17 of 152 (11%) had CVM. Anomalies detected included: bicuspid aortic valve in 5 (3%), isolated dilated ascending aorta in 4 (3%), coarctation of the aorta in 1, partial anomalous pulmonary venous connection in 1, anomalous, intramural coronary artery in 1, bicuspid pulmonary valve in 1, and other anomalies in 4. Most were previously undiagnosed (11 of 17, 65%). Fourteen of 52 families (27%) had ≥1 relative with CVM. Overall, 7 of 55 siblings (13%), 5 of 46 fathers (11%) and 5 of 51 mothers (10%) had CVM. Although the incidence of CVM in first-degree relatives of HLHS probands was lower in this cohort than previously reported, it remained substantial, with at least one additional member having CVM in 27% of families. The frequent occurrence of undiagnosed CVM highlights the importance of routine familial screening in HLHS. In fact, even if screening was done in childhood, it may be appropriate to screen again in the third or fourth decade to exclude isolated enlargement of the ascending aorta.

Dilated cardiomyopathy (DCM) is a leading cause of heart failure. In families with autosomal-dominant DCM, heterozygous missense mutations were identified in RNA-binding motif protein 20 (RBM20), a spliceosome protein induced during early cardiogenesis. Dermal fibroblasts from two unrelated patients harboring an RBM20 R636S missense mutation were reprogrammed to human induced pluripotent stem cells (hiPSCs) and differentiated to beating cardiomyocytes (CMs). Stage-specific transcriptome profiling identified differentially expressed genes ranging from angiogenesis regulator to embryonic heart transcription factor as initial molecular aberrations. Furthermore, gene expression analysis for RBM20-dependent splice variants affected sarcomeric (TTN and LDB3) and calcium (Ca(2+)) handling (CAMK2D and CACNA1C) genes. Indeed, RBM20 hiPSC-CMs exhibited increased sarcomeric length (RBM20: 1.747 ± 0.238 µm versus control: 1.404 ± 0.194 µm; P < 0.0001) and decreased sarcomeric width (RBM20: 0.791 ± 0.609 µm versus control: 0.943 ± 0.166 µm; P < 0.0001). Additionally, CMs showed defective Ca(2+) handling machinery with prolonged Ca(2+) levels in the cytoplasm as measured by greater area under the curve (RBM20: 814.718 ± 94.343 AU versus control: 206.941 ± 22.417 AU; P < 0.05) and higher Ca(2+) spike amplitude (RBM20: 35.281 ± 4.060 AU versus control:18.484 ± 1.518 AU; P < 0.05). β-adrenergic stress induced with 10 µm norepinephrine demonstrated increased susceptibility to sarcomeric disorganization (RBM20: 86 ± 10.5% versus control: 40 ± 7%; P < 0.001). This study features the first hiPSC model of RBM20 familial DCM. By monitoring human cardiac disease according to stage-specific cardiogenesis, this study demonstrates RBM20 familial DCM is a developmental disorder initiated by molecular defects that pattern maladaptive cellular mechanisms of pathological cardiac remodeling. Indeed, hiPSC-CMs recapitulate RBM20 familial DCM phenotype in a dish and establish a tool to dissect disease-relevant defects in RBM20 splicing as a global regulator of heart function.

Background— The molecular underpinnings of hypoplastic left heart are poorly understood. Staged surgical palliation has dramatically improved survival, yet eventual failure of the systemic right ventricle necessitates cardiac transplantation in a subset of patients. We sought to identify genetic determinants of hypoplastic left heart with latent right ventricular dysfunction in individuals with a Fontan circulation. Methods and Results— Evaluation of cardiac structure and function by echocardiography in patients with hypoplastic left heart and their first-degree relatives identified 5 individuals with right ventricular ejection fraction ≤40% after Fontan operation. Whole genome sequencing was performed on DNA from 21 family members, filtering for genetic variants with allele frequency MYH6 , encoding myosin heavy chain 6, in 2 patients who developed right ventricular dysfunction 3 to 11 years postoperatively. Parents and siblings who were heterozygous carriers had normal echocardiograms. Protein modeling of the 4 highly conserved amino acid substitutions, residing in both head and tail domains, predicted perturbation of protein structure and function. Conclusions— In contrast to dominant MYH6 mutations with variable penetrance identified in other congenital heart defects and dilated cardiomyopathy, this study reveals compound heterozygosity for recessive MYH6 mutations in patients with hypoplastic left heart and reduced systemic right ventricular ejection fraction. These findings implicate a shared molecular basis for the developmental arrest and latent myopathy of left and right ventricles, respectively.

Background— The goal of this study was to identify genetic determinants of plasma N-terminal proatrial natriuretic peptide (NT-proANP) in the general community by performing a large-scale genetic association study and to assess its functional significance in in vitro cell studies and on disease susceptibility. Methods and Results— Genotyping was performed across 16 000 genes in 893 randomly selected individuals, with replication in 891 subjects from the community. Plasma NT-proANP 1–98 concentrations were determined using a radioimmunoassay. Thirty-three genome-wide significant single-nucleotide polymorphisms were identified in the MTHFR-CLCN6-NPPA-NPPB locus and were all replicated. To assess the significance, in vitro functional genomic studies and clinical outcomes for carriers of a single-nucleotide polymorphism rs5063 (V32M) located in NPPA that represented the most significant variation in this genetic locus were assessed. The rs5063 variant allozyme in transfected HEK293 cells was decreased to 55±8% of wild-type protein ( P =0.01) as assessed by quantitative western blots. Carriers of rs5063 had lower NT-proANP levels (1427 versus 2291 pmol/L; P P =0.009) and were at an increased risk of stroke when compared with wild-type subjects independent of age, sex, diabetes mellitus, hypertension, atrial fibrillation, and cholesterol levels (hazard ratio, 1.6; P =0.004). Conclusions— This is the first large-scale genetic association study of circulating NT-proANP levels performed with replication and functional assessment that identified genetic variants in the MTHFR-CLCN6-NPPA-NPPB cluster to be significantly associated with NT-proANP levels. The clinical significance of this variation is related to lower NT-proANP levels, higher blood pressures, and an increased risk of stroke in the general community.

The aims of this study are to evaluate the impact of a novel immunization curriculum based on the Preferred Cognitive Styles and Decision Making Model (PCSDM) on internal medicine (IM) resident continuity clinic patient panel immunization rates, as well as resident immunization knowledge, attitudes, and practices (KAP).A cluster-randomized controlled trial was performed among 143 IM residents at Mayo Clinic to evaluate the PCSDM curriculum plus fact-based immunization curriculum (intervention) compared to fact-based immunization curriculum alone (control) on the outcomes of resident continuity clinic patient panel immunization rates for influenza, pneumococcal, tetanus, pertussis, and zoster vaccines. Pre-study and post-study immunization KAP surveys were administered to IM residents.Ninety-nine residents participated in the study. Eighty-two residents completed pre-study and post-study surveys. Influenza and pertussis immunization rates improved for both intervention and control groups. There was no significant difference in immunization rate improvement between the groups. Influenza immunization rates improved significantly by 33.4% and 32.3% in the intervention and control groups, respectively. The odds of receiving influenza immunization at the end of the study relative to pre-study for the entire study cohort was 4.6 (p 0.0001). The odds of having received pertussis immunization at the end of the study relative to pre-study for the entire study cohort was 1.2 (p = 0.0002). Both groups had significant improvements in immunization knowledge. The intervention group had significant improvements in multiple domains that assessed confidence in counseling patients on immunizations.Fact-based immunization education was useful in improving IM resident immunization rates for influenza and pertussis. The PCSDM immunization curriculum did not lead to increases in immunization rates compared with the fact-based curriculum, but it did significantly increase resident confidence in communicating with patients about vaccines.

Hypoplastic left heart syndrome (HLHS) has been shown to exhibit familial clustering with other congenital heart lesions, such as bicuspid aortic valve and other left-sided lesions. This study demonstrates inheritance of cardiomyopathies in family members of patients with HLHS, a previously

ATP-sensitive K+(KATP) channels are nucleotide-gated bioenergy sensors that enable high-fidelity feedback communication between cellular energy dynamics and membrane electric activity.1–4 Particularly dense in cardiac sarcolemma where they are composed through heteromultimeric assembly of inwardly rectifying K+channel pores, typically KCNJ11 -encoded Kir6.2 proteins, and regulatory ATP-binding cassette (ABC) proteins, namely ABCC9 -encoded SUR2A subunits, KATP channels are increasingly recognized as integral to tissue energy conservation and optimization of energy use.5 Integrated with intracellular energy pathways, sarcolemmal KATP channels are established cardioprotectors implicated in the sustenance of wellness.6–8 Knockout of the Kir6.2 KATP channel pore induces inefficient cardiac energetics associated with altered metabolic fuel selection and remodeling of the myocardial proteome, highlighting a distinct role of the channel in heart energy homeostasis.9,10 KATP channel ablation alters the expression of one tenth of largely metabolism-related protein species, exposing within the KATP channel-deficient ventricle markers of cardiovascular disease susceptibility.9,11 Indeed, disruption of the Kir6.2 KATP channel compromises cardiac protection afforded by ischemic preconditioning, impairs myocardial tolerance to sympathetic surge, and aggravates the impact of endurance challenge or hemodynamic overload precipitating heart failure under stress.12 Conversely, overexpression of channel subunits generates a protective phenotype at cellular and organ levels.13,14 High-throughput molecular technologies applied to phenotypically characterized patient and population cohorts have contributed to the deciphering of human KATP channelopathies, disease entities caused by genetic disruption of ion channel function.15–19 In cardiovascular medicine, mutations in the regulatory SUR2A subunit have been linked to KATP channelopathy-associated electric and cardiomyopathic disorders, namely the syndromes of adrenergic atrial fibrillation and dilated cardiomyopathy with tachycardia.19–21 Moreover, in clinical heart failure, a common polymorphism in …

OBJECTIVE: To assess in a US general adult population the ef- fect of the functional single-nucleotide polymorphism rs198389 in the promoter region of the gene of brain-type natriuretic peptide (BNP) on 3 commonly used BNP assays, clinical phenotype, dis- ease prevalence, overall survival, and diagnostic test characteris- tics of BNP as a biomarker. PATIENTS AND METHODS: We genotyped for rs198389 in a random sample of the general population (aged ≥45 years; n=1970; en- rolled between June 1, 1997, and September 30, 2000) from Olm- sted County, Minnesota. Patients were characterized biochemical- ly, clinically, echocardiographically, and regarding BNP molecular forms (2 assays for BNP and 1 assay for amino-terminal proBNP). Median follow-up was 9 years. RESULTS: Genotype frequencies were in Hardy-Weinberg equilib- rium (P=.98): TT genotype, n=645 (32.7%); TC genotype, n=983 (49.9%); and CC genotype, n=342 (17.4%). The C allele indepen- dently predicted higher BNP forms (P

Assembly of an inward rectifier K+ channel pore (Kir6.1/Kir6.2) and an adenosine triphosphate (ATP)-binding regulatory subunit (SUR1/SUR2A/SUR2B) forms ATP-sensitive K+ (KATP) channel heteromultimers, widely distributed in metabolically active tissues throughout the body. KATP channels are metabolism-gated biosensors functioning as molecular rheostats that adjust membrane potential-dependent functions to match cellular energetic demands. Vital in the adaptive response to (patho)physiological stress, KATP channels serve a homeostatic role ranging from glucose regulation to cardioprotection. Accordingly, genetic variation in KATP channel subunits has been linked to the etiology of life-threatening human diseases. In particular, pathogenic mutations in KATP channels have been identified in insulin secretion disorders, namely, congenital hyperinsulinism and neonatal diabetes. Moreover, KATP channel defects underlie the triad of developmental delay, epilepsy, and neonatal diabetes (DEND syndrome). KATP channelopathies implicated in patients with mechanical and/or electrical heart disease include dilated cardiomyopathy (with ventricular arrhythmia; CMD1O) and adrenergic atrial fibrillation. A common Kir6.2 E23K polymorphism has been associated with late-onset diabetes and as a risk factor for maladaptive cardiac remodeling in the community-at-large and abnormal cardiopulmonary exercise stress performance in patients with heart failure. The overall mutation frequency within KATP channel genes and the spectrum of genotype–phenotype relationships remain to be established, while predicting consequences of a deficit in channel function is becoming increasingly feasible through systems biology approaches. Thus, advances in molecular medicine in the emerging field of human KATP channelopathies offer new opportunities for targeted individualized screening, early diagnosis, and tailored therapy.

Introduction: Epidemiological studies report a male predominance in lone atrial fibrillation (LAF). Phenotypic differences between sporadic and familial LAF could aid in deciding which cases should undergo family screening. We sought to determine gender distribution in sporadic and familial LAF, gender-based differences, and phenotypic differences between sporadic and familial LAF. Methods: Since November 2000, 192 unrelated LAF probands were recruited. Sporadic LAF was defined as the absence of a family history of LAF. Familial LAF was classified as possible if one first- or second-degree relative had LAF, or confirmed if ≥ 2 relatives had LAF. Affected relatives (n = 87) of 34 confirmed familial probands were also evaluated. For unrelated LAF probands, differences in proportions and means were tested using χ2 and ANOVA, respectively. Difference in gender ratio among the family history groups was tested using mixed models. Results: Male proportion was greater among sporadic (82%) and possible familial probands (84%) than confirmed familial probands (62%), and affected relatives (54%), P < 0.001. Sporadic LAF was more common in men (62%) than women (51%), P = 0.03. More women were affected by palpitation and nocturnal symptoms than men. More patients had permanent AF in the confirmed familial group (27%), compared with the possible familial (7%) and the sporadic LAF group (8%), P = 0.05, but no other phenotypic discriminators were identified. Conclusions: Male predilection for LAF is attenuated as the likelihood of dominant Mendelian inheritance increases. Increased frequency of “sporadic” LAF among men could be partially due to X-linked recessive inheritance. Finally, sporadic and familial LAF are clinically indistinguishable.

Atrial fibrillation is a common arrhythmia that is hereditary in a small subgroup of patients. In a family with 11 clinically affected members, we mapped an atrial fibrillation locus to chromosome 1p36-p35 and identified a heterozygous frameshift mutation in the gene encoding atrial natriuretic peptide. Circulating chimeric atrial natriuretic peptide (ANP) was detected in high concentration in subjects with the mutation, and shortened atrial action potentials were seen in an isolated heart model, creating a possible substrate for atrial fibrillation. This report implicates perturbation of the atrial natriuretic peptide-cyclic guanosine monophosphate (cGMP) pathway in cardiac electrical instability.

Dilated cardiomyopathy (DCM) is a primary heart muscle disease characterized by ventricular dilatation and impaired systolic function. DCM is the most common form of cardiomyopathy, and is also the commonest cause for heart failure and cardiac transplantation in adults and children. The frequency of familial occurrence of DCM had been significantly underestimated in the past, but extensive family studies showed that 35–45% of cases are familial. This recognition led to molecular genetic investigations that have further enhanced the understanding of the molecular pathogenesis of DCM. In this review, we discuss these new insights into the genetics of DCM which will have important implications for the diagnosis, risk stratification and treatment of DCM.

Background A 53-year-old female presented with a 10-year history of paroxysmal atrial fibrillation (AF), precipitated by activity and refractory to medical therapy. In the absence of traditional risk factors for disease, a genetic defect in electrical homeostasis underlying stress-induced AF was explored. Investigations Echocardiography, cardiac perfusion stress imaging, invasive electrophysiology with isoproterenol provocation, genomic DNA sequencing of KATP channel genes, exclusion of mutation in 2,000 individuals free of AF, reconstitution of channel defect with molecular phenotyping, and verification of pathogenic link in targeted knockout. Diagnosis KATP channelopathy caused by missense mutation (Thr1547Ile) of the ABCC9 gene conferring predisposition to adrenergic AF originating from the vein of Marshall. Management Disruption of arrhythmogenic gene–environment substrate at the vein of Marshall by radiofrequency ablation.

The cardiac sodium channel (SCN5A) is a target for the treatment of arrhythmias. We hypothesized that vulnerability to atrial fibrillation (AF) could be caused by genetic variation in SCN5A. We recruited 157 patients with early-onset AF who lacked traditional risk factors, and 314 matched controls. SCN5A was subject to targeted genotyping of a common loss-of-function H558R polymorphism and comprehensive mutation scanning. Genotype frequencies in the AF cohort vs controls were as follows: HH, 50 vs 63%; HR, 40 vs 33%; and RR, 10 vs 4% (P = 0.008). Additional coding sequence mutations were ruled out. The R558 allele was more common in patients than in controls (30 vs 21%, P = 0.002), conferring an odds ratios for AF of 1.6 (95% confidence interval 1.2-2.2). The SCN5A R558 allele, present in one-third of the population, thus constitutes a risk factor for lone AF and may increase susceptibility to sodium channel blocker-induced proarrhythmia.

For inherited cardiomyopathies, abnormal sensitivity to intracellular calcium (Ca(2+) ), incurred from genetic mutations, initiates subsequent molecular events leading to pathological remodeling. Here, we characterized the effect of β-adrenergic stress in familial dilated cardiomyopathy (DCM) using human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) from a patient with RBM20 DCM. Our findings suggest that β-adrenergic stimulation accelerated defective Ca(2+) homeostasis, apoptotic changes, and sarcomeric disarray in familial DCM hiPSC-CMs. Furthermore, pharmacological modulation of abnormal Ca(2+) handling by pretreatment with β-blocker, carvedilol, or Ca(2+) -channel blocker, verapamil, significantly decreased the area under curve, reduced percentage of disorganized cells, and decreased terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive apoptotic loci in familial DCM hiPSC-CMs after β-adrenergic stimulation. These translational data provide patient-based in vitro analysis of β-adrenergic stress in RBM20-deficient familial DCM hiPSC-CMs and evaluation of therapeutic interventions to modify heart disease progression, which may be personalized, but more importantly generalized in the clinic.

The goal of this study was to identify genetic determinants of plasma N-terminal proatrial natriuretic peptide (NT-proANP) in the general community by performing a large-scale genetic association study and to assess its functional significance in in vitro cell studies and on disease susceptibility.

Importance Spontaneous coronary artery dissection (SCAD) is a major cause of acute coronary syndrome in young women, especially among those without traditional cardiovascular risk factors. Prior efforts to study SCAD have been hampered by underrecognition and lack of registry-based studies. Risk factors and pathogenesis remain largely undefined, and inheritability has not been reported. Observations Using novel research methods, patient champions, and social media, the Mayo Clinic SCAD Registry has been able to better characterize this condition, which was previously considered rare. Of 412 patient enrollees, we identified 5 familial cases of SCAD comprising affected mother-daughter, identical twin sister, sister, aunt-niece, and first-cousin pairs, implicating both recessive and dominant modes of inheritance. The mother-daughter pair also reported fatal myocardial infarction in 3 maternal relatives. None of the participants had other potential risk factors for SCAD, including connective tissue disorders or peripartum status. Conclusions and Relevance To our knowledge, this series is the first to identify a familial association in SCAD suggesting a genetic predisposition. Recognition of SCAD as a heritable disorder has implications for at-risk family members and furthers our understanding of the pathogenesis of this complex disease. Whole-exome sequencing provides a unique opportunity to identify the molecular underpinnings of SCAD susceptibility.

Atrial fibrillation is a rhythm disorder characterized by chaotic electrical activity of cardiac atria. Predisposing to stroke and heart failure, this common condition is increasingly recognized as a heritable disorder. To identify genetic defects conferring disease susceptibility, patients with idiopathic atrial fibrillation, lacking traditional risk factors, were evaluated. Genomic DNA scanning revealed a nonsense mutation in KCNA5 that encodes Kv1.5, a voltage-gated potassium channel expressed in human atria. The heterozygous E375X mutation, present in a familial case of atrial fibrillation and absent in 540 unrelated control individuals, introduced a premature stop codon disrupting the Kv1.5 channel protein. The truncation eliminated the S4-S6 voltage sensor, pore region and C-terminus, preserving the N-terminus and S1-S3 transmembrane domains that secure tetrameric subunit assembly. Heterologously expressed recombinant E375X mutant failed to generate the ultrarapid delayed rectifier current I(Kur) vital for atrial repolarization and exerted a dominant-negative effect on wild-type current. Loss of channel function translated into action potential prolongation and early after-depolarization in human atrial myocytes, increasing vulnerability to stress-provoked triggered activity. The pathogenic link between compromised Kv1.5 function and susceptibility to atrial fibrillation was verified, at the organism level, in a murine model. Rescue of the genetic defect was achieved by aminoglycoside-induced translational read-through of the E375X premature stop codon, restoring channel function. This first report of Kv1.5 loss-of-function channelopathy establishes KCNA5 mutation as a novel risk factor for repolarization deficiency and atrial fibrillation.

Objectives The aims of this study were to identify and characterize familial cases of atrial fibrillation (AF) in our clinical practice and to determine whether AF is genetically heterogeneous. Background Atrial fibrillation is not generally regarded as a heritable disorder, yet a genetic locus for familial AF was previously mapped to chromosome 10. Methods Of 2,610 patients seen in our arrhythmia clinic during an 18-month study period, 914 (35%) were diagnosed with AF. Familial cases were identified by history and medical records review. Four multi-generation families with autosomal dominant AF (FAF 1 to 4) were tested for linkage to the chromosome 10 AF locus. Results Fifty probands (5% of all AF patients; 15% of lone AF patients) were identified with lone AF (age 41 ± 9 years) and a positive family history (1 to 9 additional relatives affected). In FAF 1 to 3, AF was associated with rapid ventricular response. In contrast, AF in FAF-4 was associated with a slow ventricular response and, with progression of the disease, junctional rhythm and cardiomyopathy. Genotyping of FAF 1 to 4 with deoxyribonucleic acid markers spanning the chromosome 10q22-q24 region excluded linkage of AF to this locus. In FAF-4, linkage was also excluded to the chromosome 3p22-p25 and lamin A/C loci associated with familial AF, conduction system disease, and dilated cardiomyopathy. Conclusions Familial AF is more common than previously recognized, highlighting the importance of genetics in disease pathogenesis. In four families with AF, we have excluded linkage to chromosome 10q22-q24, establishing that at least two disease genes are responsible for this disorder.

CM, Bergin ML, Kiess MC, Marcotte F, et al. Prospective multicenter study of pregnancy outcomes in women with heart disease. Circulation 2001;104:515– 521. 3. Skjaerpe T, Hegrenaes L, Hatle L. Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. Circulation 1985;72:810–818. 4. Hatle L, Angelsen B. Pulsed and continuous wave Doppler in diagnosis and assessment of various heart lesions. In: Hatle L, Angelsen B, eds. Doppler Ultrasound in Cardiology: Physical Principles and Clinical Applications. Philadelphia: Lea & Febiger, 1982:97–292. 5. Bonow RO, Carabello B, de Leon AC Jr, Edmunds LH Jr, Fedderly BJ, Freed MD, Gaasch WH, McKay CR, Nishimura RA, O’Gara PT, et al. ACC/AHA guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease). J Am Coll Cardiol 1998;32:1486–1588. 6. Perry GJ, Helmcke F, Nanda NC, Byard C, Soto B. Evaluation of aortic insufficiency by Doppler color flow mapping. J Am Coll Cardiol 1987;9:952– 959. 7. Stamm RB, Carabello BA, Mayers DL, Martin RP. Two-dimensional echocardiographic measurement of left ventricular ejection fraction: prospective analysis of what constitutes an adequate determination. Am Heart J 1982;104:136– 144. 8. Arias F, Pineda J. Aortic stenosis and pregnancy. J Reprod Med 1978;20:229– 232. 9. Lao TT, Sermer M, MaGee L, Farine D, Colman JM. Congenital aortic stenosis and pregnancy—a reappraisal. Am J Obstet Gynecol 1993;169:540–545. 10. Hameed A, Karaalp IS, Tummala PP, Wani OR, Canetti M, Akhter MW, Goodwin M, Zapadinsky N, Elkayam U. The effect of valvular heart disease on maternal and fetal outcome of pregnancy. J Am Coll Cardiol 2001;37:893–899.

Background — Autosomal dominant hypertrophic cardiomyopathy (HCM) is caused by inherited defects of sarcomeric proteins. We tested the hypothesis that homozygosity for a sarcomeric protein defect can cause recessive HCM. Methods and Results — We studied a family with early-onset cardiomyopathy in 3 siblings, characterized by mid-cavitary hypertrophy and restrictive physiology. Genotyping of DNA markers spanning 8 genes for autosomal dominant HCM revealed inheritance of an identical paternal and maternal haplotype at the essential light chain of myosin locus by the affected children. Sequencing showed that these individuals were homozygous for a Glu143Lys substitution of a highly conserved amino acid that was absent in 150 controls. Family members with one Glu143Lys allele had normal echocardiograms and ECGs, even in late adulthood, whereas those with two mutant alleles developed severe cardiomyopathy in childhood. These findings, coupled with previous studies of myosin light chain structure and function in the heart, suggest a loss-of-function disease mechanism. Conclusions — Distinct mutations affecting the same sarcomeric protein can cause either dominant or recessive cardiomyopathy. Electrostatic charge reversal of a highly conserved amino acid may be benign in the heterozygous state as the result of compensatory mechanisms that preserve cardiac structure and function. By contrast, homozygous carriers of a sarcomeric protein defect may have a malignant course. Recognizing recessive inheritance in children with cardiomyopathy is essential for appropriate family counseling.

Objectives To evaluate the impact of a functional genetic variant in the natriuretic peptide clearance receptor, NPR3, on circulating natriuretic peptides (NPs) and myocardial structure and function in the general community. Background NPR3 plays an important role in the clearance of NPs and through direct signaling mechanisms modulates smooth muscle cell function and cardiac fibroblast proliferation. A NPR3 nonsynonymous single nucleotide polymorphism (SNP) rs2270915, resulting in a N521D substitution in the intracellular catalytic domain that interacts with Gi could affect receptor function. Whether this SNP is associated with alterations in NPs levels and altered cardiac structure and function is unknown. Methods DNA samples of 1931 randomly selected residents of Olmsted County, Minnesota were genotyped. Plasma NT-proANP1-98, ANP1-28, proBNP1-108, NT-proBNP1-76, BNP1-32 and BNP3-32 levels were measured. All subjects underwent comprehensive echocardiography. Results Genotype frequencies for rs2270915 were as follows: (A/A 60%, A/G 36%, G/G 4%). All analyses performed were for homozygotes G/G versus wild type A/A plus the heterozygotes A/G. Diastolic dysfunction was significantly more common (p = 0.007) in the homozygotes G/G (43%) than the A/A+A/G (28%) group. Multivariate regression adjusted for age, sex, body mass index and hypertension demonstrated rs2270915 to be independently associated with diastolic dysfunction (odds ratio 1.94, p = 0.03). There was no significant difference in NPs levels between the 2 groups suggesting that the clearance function of the receptor was not affected. Conclusions A nonsynonymous NPR3 SNP is independently associated with diastolic dysfunction and this association does not appear to be related to alterations in circulating levels of natriuretic peptides.

ATP-sensitive K+ (K(ATP)) channel mutations have been identified in individuals with dilated cardiomyopathy and overt heart failure. Here, a common E23K functional polymorphism in the Kir6.2 channel pore versus cardiac phenotype was studied in a cross-sectional community-based cohort (n = 2,031). The KK genotype was associated with greater left ventricular size among subjects with increased stress load due to hypertension. These findings implicate Kir6.2 K23 as a risk factor for adverse subclinical myocardial remodeling, and underscore the significance of cardiac K(ATP) channels within the population.

Background The cardiac hormone atrial natriuretic peptide (ANP) induces natriuresis, vasodilation and inhibits aldosterone through the activation of the guanylyl cyclase A receptor (GC-A) and the second messenger cGMP. ANP possesses also metabolic properties enhancing lipolysis and release of the adipokine adiponectin. Previous studies in general populations reported that the minor G allele of the ANP genetic variant rs5068 is associated with increased circulating levels of ANP and B-type natriuretic peptide, lower blood pressure (BP), and reduced risk of hypertension. We recently reported that in the general population from Olmsted County, MN, USA the G allele of rs5068 is associated not only with increased levels of ANP and lower BP but also with lower BMI, prevalence of obesity and metabolic syndrome. To advance our understanding of the phenotype associated with rs5068 we analyzed a community-based cohort from Sicily, Italy. Our second aim was to advance a potential therapeutics for cardiometabolic disease employing a novel long-acting ANP, MANP whose biological actions were defined in canines and in a rat model of metabolic syndrome.

ATP-sensitive K+ (KATP) channels integrate cellular energy signals with membrane electrical activity. Heteromultimers of KCNJ11-encoded inwardly rectifying potassium Kir6.2 channels and ABCC9-encoded ATP-binding cassette SUR2A proteins, sarcolemmal KATP channels are vital in heart energy homeostasis. Knockout of the Kir6.2 pore compromises cardioprotection afforded by ischemic preconditioning, impairs tolerance to sympathetic surge, and aggravates the impact of endurance challenge or hemodynamic load precipitating heart failure under stress. In human cardiovascular medicine, mutations in the regulatory SUR2A subunit have been linked to KATP channelopathy-associated electrical and cardiomyopathic disorders, including syndromes of adrenergic atrial fibrillation and dilated cardiomyopathy with tachycardia. In clinical heart failure, a common polymorphism in the Kir6.2 subunit has been identified as a biomarker for impaired performance in stress-test. The Kir6.2 K23 allele, present in over half the population, has been further pinpointed as a risk factor for susceptibility to maladaptive cardiac remodeling in hypertension. Cardiovascular disorders associated with genetic variation in KATP channel genes also include myocardial infarction and ventricular fibrillation. Thus, advances in molecular medicine have enabled a growing understanding of KATP channel function in health and disease, underscoring the impact on individual and public cardiovascular wellness.

Background We reviewed our experience with the surgical management of supravalvar aortic stenosis (SVAS) to determine long-term outcomes and factors related to late reoperation. Methods Between August 1956 and May 2009, 78 patients (50 males) underwent surgical correction of SVAS. Median age was 10.4 years (range, 16 days to 55.2 years). Mean preoperative gradient was 57.2 ± 21.9 mm Hg with a mean peak gradient of 99.5 ± 34.8 mm Hg. Supravalvar aortic stenosis was discrete in 51 patients (64%) and diffuse in 27 patients (35%). Aortic valve stenosis was present in 22 patients (29%). Williams-Beuren syndrome was present in 32 patients (41%). Results Surgery was either a diamond-shaped patch in 67 patients (85.9%) or a pantaloons-shaped patch in 11 patients (14.1%). Aortic valve intervention was required in 20 patients (25.64%). Mean gradient immediately after repair was 25 ± 25 mm Hg, with 13 patients (16.7%) having a residual gradient. A high residual gradient was more likely in the diffuse group (odds ratio, 3.73; 95% confidence interval, 1.07 to 12.98). There were 2 (2.6%) early deaths, both with diffuse SVAS. Median follow-up was 19.8 years; maximum was 48.5 years. The mean gradient across the left ventricular outflow tract at late follow-up was 8.8 mm Hg (95% confidence interval, 3.7 to 14.01). Overall survival was estimated at 90% ± 7%, 84% ± 9%, and 8%2 ± 10% at 5, 10, and 20 years, respectively. Predictors of mortality were age younger than 2 years ( p = 0.021), diffuse SVAS ( p = 0.045), aortic valve stenosis ( p = 0.032), and high postoperative gradient ( p = 0.023). Presence of Williams-Beuren syndrome did not affect survival ( p = 0.305). Freedom from late reoperation was 97% ± 4%, 93% ± 7%, and 86% ± 10% at 5, 10, and 20 years, respectively. Significant aortic valve disease ( p p = 0.009) were risk factors for late reoperation. Conclusions Surgical repair for SVAS can be performed with a single-patch technique with good long-term outcome. Late mortality and need for reoperation are more likely with diffuse SVAS or the presence of aortic valve stenosis.

Objectives We sought to define the cardiometabolic phenotype associated with rs5068, a genetic variant of the atrial natriuretic peptide (ANP) gene. Background The ANP and B-type natriuretic peptide play an important role in cardiorenal homeostasis but also exert metabolic actions. Methods We genotyped 1,608 randomly selected residents from Olmsted County, Minnesota. Subjects were well-characterized. Results Genotype frequencies were: AA 89.9%, AG 9.7%, and GG 0.4%; all subsequent analyses were AA versus AG+GG. The G allele was associated with increased plasma levels of N-terminal pro-atrial natriuretic peptide (p = 0.002), after adjustment for age and sex. The minor allele was also associated with lower body mass index (BMI) (p = 0.006), prevalence of obesity (p = 0.002), waist circumference (p = 0.021), lower levels of C-reactive protein (p = 0.027), and higher values of high-density lipoprotein cholesterol (p = 0.019). The AG+GG group had a lower systolic blood pressure (p = 0.011) and lower prevalence of myocardial infarction (p = 0.042). The minor allele was associated with a lower prevalence of metabolic syndrome (p = 0.025). The associations between the G allele and high-density lipoprotein cholesterol, C-reactive protein values, myocardial infarction, and metabolic syndrome were not significant, after adjusting for BMI; the associations with systolic blood pressure, BMI, obesity, and waist circumference remained significant even after adjusting for N-terminal pro-atrial natriuretic peptide. Conclusions In a random sample of the general U.S. population, the minor allele of rs5068 is associated with a favorable cardiometabolic profile. These findings suggest that rs5068 or genetic loci in linkage disequilibrium might affect susceptibility for cardiometabolic diseases and support the possible protective role of natriuretic peptides by their favorable effects on metabolic function. Replication studies are needed to confirm our findings.

In 1866, Dr. Wilhelm Ebstein described the postmortem findings of severe malformation of the tricuspid valve and a patent foramen ovale in a patient with a history of cyanosis, dyspnea, and palpitations.’ Since that initial description, the tendency for palpitations, tachycardia, and occasionally sudden death to develop in patients with Ebstein’s anomaly of the tricuspid valve has been recognized.2-10 Furthermore, the important association between preexcitation and Ebstein’s anomaly has been established. Patients with Ebstein’s anomaly are predisposed to arrhythmias because of abnormal cardiac anatomy, and they tend to decompensate hemodynamitally when an arrhythmia occurs. Tachyarrhythmias are poorly tolerated in the setting of right ventricular dysfunction, tricuspid insufficiency, and an atria1 septal defect, resulting in increased right-to-left shunting, hypoxemia, and reduced cardiac output.8u Consequently, anatomic and electrophysiologic abnormalities in Ebstein’s anomaly are interrelated determinants of hemodynamic severity and clinical course. Following is a review of the unique pathologic, electrocardiographic, and electrophysiologic features of Ebstein’s anomaly that predispose patients

Genomewide association studies have reproducibly identified rs2200733T on chromosome 4q25 as a risk factor for the most common sustained arrhythmia, atrial fibrillation (AF). The biologic basis for cardiac electrical instability conferred by this noncoding variant is unknown. The aim of this study was to investigate potential relations between rs2200733 versus clinical and electrocardiographic traits in a cohort of patients with early-onset AF who lack traditional risk factors. Congruent with previous reports, the minor T allele was overrepresented in subjects with lone AF. All genotype groups were statistically similar for age at diagnosis, gender distribution, family history, body mass index, AF type, ventricular rate, QRS duration, corrected QT interval, and use of PR interval--prolonging medications. However, a novel association was identified between the TT genotype and duration of the PR interval. The TT group had a mean PR interval of 189.5 ± 35.8 ms in comparison to mean PR intervals of 172.0 ± 29.0 and 171.0 ± 27.1 ms for the CT and CC groups, respectively (p = 0.013 and p = 0.0056). In conclusion, PR interval length, an established risk factor for AF, represents an rs2200733-associated intermediate phenotype.

PAGOD syndrome is a rare condition characterized by multiple congenital anomalies including pulmonary artery and lung hypoplasia, agonadism, diaphragmatic abnormalities, cardiac defects, omphalocele, and various genital anomalies. The etiology of this condition is unknown but the spectrum of birth defects is similar to the developmental anomalies observed in vitamin A deficiency animal models. We describe an infant with PAGOD syndrome phenotype. The patient had a normal male karyotype and no copy number changes were seen on chromosome genomic hybridization (CGH) microarray. Endocrine evaluation was consistent with primary hypogonadism. The testes and Mullerian structures were absent by imaging studies, raising the possibility of arrest of early gonadogenesis. The plasma free vitamin A was low, consistent with moderate to severe vitamin A deficiency; the maternal plasma vitamin A level was normal. During pregnancy maternal vitamin A is taken up by retinol binding protein 4 (RBP4) which is expressed in the embryonic visceral endoderm from pregastrulational stages. This transport is mediated via the specific membrane receptor for RBP, stimulated by retinoic acid 6 (STRA6). STRA6 is widely expressed in human organ systems including the placenta during embryonic development. Mutations in the STRA6 gene result in Matthew-Wood syndrome, which demonstrates significant phenotypic overlap with PAGOD syndrome. Sequencing of STRA6 coding regions in our patient, revealed no mutations. We present a case of PAGOD syndrome with a review of the literature, posing the hypothesis that a vitamin A metabolic defect, other than transport mediated by STRA6 receptor, might have an etiological role in the development of this multiple congenital anomalies syndrome.

ATP-sensitive K+ (KATP) channels maintain cardiac homeostasis under stress, as revealed by murine gene knockout models of the KCNJ11-encoded Kir6.2 pore. However, the translational significance of KATP channels in human cardiac physiology remains largely unknown. Here, the frequency of the minor K23 allele of the common functional Kir6.2 E23K polymorphism was found overrepresented in 115 subjects with congestive heart failure compared to 2,031 community-based controls (69 vs. 56%, P < 0.001). Moreover, the KK genotype, present in 18% of heart failure patients, was associated with abnormal cardiopulmonary exercise stress testing. In spite of similar baseline heart rates at rest among genotypic subgroups (EE: 72.2 ± 2.3, EK: 75.0 ± 1.8 and KK: 77.1 ± 3.0 bpm), subjects with the KK genotype had a significantly reduced heart rate increase at matched workload (EE: 32.8 ± 2.7%, EK: 28.8 ± 2.1%, KK: 21.7 ± 2.6%, P < 0.05), at 75% of maximum oxygen consumption (EE: 53.9 ± 3.9%, EK: 49.9 ± 3.1%, KK: 36.8 ± 5.3%, P < 0.05), and at peak VO2 (EE: 82.8 ± 6.0%, EK: 80.5 ± 4.7%, KK: 59.7 ± 8.1%, P < 0.05). Molecular modeling of the tetrameric Kir6.2 pore structure revealed the E23 residue within the functionally relevant intracellular slide helix region. Substitution of the wild-type E residue with an oppositely charged, bulkier K residue would potentially result in a significant structural rearrangement and disrupted interactions with neighboring Kir6.2 subunits, providing a basis for altered high-fidelity KATP channel gating, particularly in the homozygous state. Blunted heart rate response during exercise is a risk factor for mortality in patients with heart failure, establishing the clinical relevance of Kir6.2 E23K as a biomarker for impaired stress performance and underscoring the essential role of KATP channels in human cardiac physiology.

Atrial fibrillation (AF) is a heritable, genetically heterogeneous disorder. To identify gene defects that cause or confer susceptibility to AF, a cohort of 268 unrelated patients with idiopathic forms of familial and sporadic AF was recruited. LMNA, encoding the nuclear membrane proteins, lamin A/C, was selected as a candidate gene for lone AF based on its established association with a syndrome of dilated cardiomyopathy, conduction system disease, and AF. Comprehensive mutation scanning identified only 1 potentially pathogenic mutation. In conclusion, LMNA mutations rarely cause lone AF and routine genetic testing of LMNA in these patients does not appear warranted.

Objectives We sought to determine the physiologic actions and potential therapeutic applications of mutant atrial natriuretic peptide (mANP). Background The cardiac hormone atrial natriuretic peptide (ANP) is a 28-amino acid (AA) peptide that consists of a 17-AA ring structure together with a 6-AA N-terminus and a 5-AA C-terminus. In a targeted scan for sequence variants within the human ANP gene, a mutation was identified that results in a 40-AA peptide consisting of native ANP(1-28)and a C-terminal extension of 12 AA. We have termed this peptide mutant ANP. Methods In vitro 3′,5′-cyclic guanosine monophosphate (cGMP) activation in response to mANP was studied in cultured human cardiac fibroblasts known to express natriuretic peptide receptor A. The cardiorenal and neurohumoral properties of mANP compared with ANP were assessed in vivo in normal dogs. Results We observed an incremental in vitro cGMP dose response with increasing concentrations of mANP. In vivo with high-dose mANP (33 pmol/kg/min), we observed significantly greater plasma cGMP activation, diuretic, natriuretic, glomerular filtration rate enhancing, renin-angiotensin-aldosterone system inhibiting, cardiac unloading, and blood pressure lowering properties when compared with native ANP. Low-dose mANP (2 pmol/kg/min) has natriuretic and diuretic properties without altering systemic hemodynamics compared with no natriuretic or diuretic response with low-dose native ANP. Conclusions These studies establish that mANP activates cGMP in vitro and exerts greater and more sustained natriuretic, diuretic, glomerular filtration rate, and renal blood flow enhancing actions than native ANP in vivo.

We identified a unique family with autosomal dominant heart disease variably expressed as restrictive cardiomyopathy (RCM), hypertrophic cardiomyopathy (HCM), and dilated cardiomyopathy (DCM), and sought to identify the molecular defect that triggered divergent remodeling pathways. Polymorphic DNA markers for nine sarcomeric genes for DCM and/or HCM were tested for segregation with disease. Linkage to eight genes was excluded, but a cardiac troponin T (TNNT2) marker cosegregated with the disease phenotype. Sequencing of TNNT2 identified a heterozygous missense mutation resulting in an I79N substitution, inherited by all nine affected family members but by none of the six unaffected relatives. Mutation carriers were diagnosed with RCM (n = 2), non-obstructive HCM (n = 3), DCM (n = 2), mixed cardiomyopathy (n = 1), and mild concentric left ventricular hypertrophy (n = 1). Endomyocardial biopsy in the proband revealed non-specific fibrosis, myocyte hypertrophy, and no myofibrillar disarray. Restrictive Doppler filling patterns, atrial enlargement, and pulmonary hypertension were observed among family members regardless of cardiomyopathy subtype. Mutation of a sarcomeric protein gene can cause RCM, HCM, and DCM within the same family, underscoring the necessity of comprehensive morphological and physiological cardiac assessment in familial cardiomyopathy screening.

Introduction Atrial fibrillation (AF) is a heritable disorder with male predilection, suggesting a sex chromosome defect in certain patients. Loss-of-function truncation mutations in EMD, encoding the nuclear membrane protein emerin, cause X-linked Emery-Dreifuss muscular dystrophy (EDMD) characterized by localized contractures and skeletal myopathy in adolescence, sinus node dysfunction (SND) in early adulthood, and atrial fibrillation as a variably associated trait. This study sought to identify the genetic basis for male-restricted, nonsyndromic sinus node dysfunction and AF in a multigenerational family. Methods and results Genealogical and medical records, and DNA samples, were obtained. Progressive SND and AF occurred in four males related through maternal lineages, consistent with X-linked inheritance. Skeletal myopathy was absent, even at advanced ages. Targeted X chromosome genotyping mapped the disease locus to Xq28, implicating EMD as a positional candidate gene. DNA sequencing revealed hemizygosity for an in-frame 3-bp deletion in EMD (Lys37del) in affected males, disrupting a residue within the LEM binding domain critical for nuclear assembly but leaving the remainder of the protein intact. Buccal epithelial cell staining with emerin antibody demonstrated near-total functional loss of emerin. Female relatives underwent prospective electrocardiographic and genetic testing. Those heterozygous for Lys37del had approximately 50-70% emerin-positive nuclei and variable degrees of paroxysmal supraventricular arrhythmia. Conclusions Mutation of EMD can underlie X-linked familial AF. Lys37del is associated with epithelial cell emerin deficiency, as in EDMD, yet it causes electrical atriomyopathy in the absence of skeletal muscle disease. Targeted genetic testing of EMD should be considered in patients with SND-associated AF and/or family history suggesting X-linked inheritance.

To test the hypothesis that actin dysfunction leads to heart failure, patients with hereditary idiopathic dilated cardiomyopathy (IDC) were examined for mutations in the cardiac actin gene ( ACTC ). Missense mutations in ACTC that cosegregate with IDC were identified in two unrelated families. Both mutations affect universally conserved amino acids in domains of actin that attach to Z bands and intercalated discs. Coupled with previous data showing that dystrophin mutations also cause dilated cardiomyopathy, these results raise the possibility that defective transmission of force in cardiac myocytes is a mechanism underlying heart failure.