The early genetic pathway(s) triggering the pathogenesis of coronary artery disease (CAD) and myocardial infarction (MI) remain largely unknown. Here, we describe an autosomal dominant form of CAD/MI (adCAD1) that is caused by the deletion of seven amino acids in transcription factor MEF2A. The deletion disrupts nuclear localization of MEF2A, reduces MEF2A-mediated transcription activation, and abolishes synergistic activation by MEF2A and by the transcription factor GATA-1 through a dominant-negative mechanism. The MEF2A protein demonstrates strong expression in the endothelium of coronary arteries. These results identify a pathogenic gene for a familial vascular disease with features of CAD and implicate the MEF2A signaling pathway in the pathogenesis of CAD/MI.

Background: Hypertrophic cardiomyopathy (HCM) is the leading cause of sudden cardiac death (SCD) in children and young adults. Our objective was to develop and validate a SCD risk prediction model in pediatric HCM to guide SCD prevention strategies. Methods: In an international multi-center observational cohort study, phenotype-positive patients with isolated HCM <18 years at diagnosis were eligible. The primary outcome variable was the time from diagnosis to a composite of SCD events at 5-year follow-up: SCD, resuscitated sudden cardiac arrest (SCA), and aborted SCD, i.e. appropriate shock following primary prevention ICD. Competing risk models with cause-specific hazard regression were used to identify and quantify clinical and genetic factors associated with SCD. The cause-specific regression model was implemented using boosting, and tuned with ten repeated four-fold cross-validations. The final model was fitted using all data with the tuned hyperparameter value that maximizes the c-statistic, and its performance was characterized using c-statistic for competing risk models. The final model was validated in an independent external cohort (SHaRe, n=285). Results: Overall, 572 patients met eligibility criteria with 2855 patient-years of follow-up. The 5-year cumulative proportion of SCD events was 9.1% (14 SCD, 25 resuscitated SCA, 14 aborted SCD). Risk predictors included age at diagnosis, documented non-sustained ventricular tachycardia, unexplained syncope, septal diameter z-score, LV posterior wall diameter z-score, LA diameter z-score, peak LV outflow tract (LVOT) gradient, and presence of a pathogenic variant. Unlike adults, LVOT gradient had an inverse association, and family history of SCD had no association with SCD. Clinical and clinical/genetic models were developed to predict 5-year freedom from SCD. Both models adequately discriminated patients with and without SCD events with a c-statistic of 0.75 and 0.76 respectively and demonstrated good agreement between predicted and observed events in the primary and validation cohorts (validation c-statistic 0.71 and 0.72 respectively). Conclusions: Our study provides a validated SCD risk prediction model with over 70% prediction accuracy and incorporates risk factors that are unique to pediatric HCM. An individualized risk prediction model has the potential to improve the application of clinical practice guidelines and shared decision-making for ICD insertion. Clinical Trial Registration: URL: https://clinicaltrials.gov Unique Identifier: NCT04036799

The cardiac sodium channel Nav 1.5 is essential for the physiological function of the heart and contributes to lethal cardiac arrhythmias and sudden death when mutated. Here, we report that MOG1, a small protein that is highly conserved from yeast to humans, is a central component of the channel complex and modulates the physiological function of Nav 1.5. The yeast two-hybrid screen identified MOG1 as a new protein that interacts with the cytoplasmic loop II (between transmembrane domains DII and DIII) of Nav 1.5. The interaction was further demonstrated by both in vitro glutathione S-transferase pull-down and in vivo co-immunoprecipitation assays in both HEK293 cells with co-expression of MOG1 and Nav1.5 and native cardiac cells. Co-expression of MOG1 with Nav1.5 in HEK293 cells increased sodium current densities. In neonatal myocytes, overexpression of MOG1 increased current densities nearly 2-fold. Western blot analysis revealed that MOG1 increased cell surface expression of Nav1.5, which may be the underlying mechanism by which MOG1 increased sodium current densities. Immunostaining revealed that in the heart, MOG1 was expressed in both atrial and ventricular tissues with predominant localization at the intercalated discs. In cardiomyocytes, MOG1 is mostly localized in the cell membrane and co-localized with Nav1.5. These results indicate that MOG1 is a critical regulator of sodium channel function in the heart and reveal a new cellular function for MOG1. This study further demonstrates the functional diversity of Nav1.5-binding proteins, which serve important functions for Nav1.5 under different cellular conditions.

TBX5 is a T-box transcription factor that plays a critical role in organogenesis. Seven missense mutations in TBX5 have been identified in patients with Holt-Oram syndrome characterized by congenital heart defects and upper limb abnormalities. However, the functional significance and molecular pathogenic mechanisms of these mutations are not clear. In this study we describe functional defects in DNA binding, transcriptional activity, protein-protein interaction, and cellular localization of mutant TBX5 with these missense mutations (Q49K, I54T, G80R, G169R, R237Q, R237W, and S252I). Mutations G80R, R237Q, and R237W represent a group of mutations that dramatically reduce DNA-binding activity of TBX5, leading to reduced transcription activation by TBX5 and the loss of synergy in transcriptional activation between TBX5 and NKX2.5. The second group of mutations includes Q49K, I54T, G169R, and S252I, which have no or moderate effect on DNA-binding activity and the function of transcription activation of TBX5 but cause the complete loss of synergistic transcription activity between TBX5 and NKX2.5. All seven missense mutations greatly reduced the interaction of TBX5 with NKX2.5 in vivo and in vitro. Immunofluorescent staining showed that wild type TBX5 was localized completely into the nucleus, but mutants were localized in both nucleus and cytoplasm. These results demonstrate that all seven missense mutations studied here are functional mutations with a spectrum of defects ranging from decreases in DNA-binding activity and transcriptional activation to the dramatic reduction of interaction between TBX5 and NKX2.5, and loss of synergy in transcriptional activation between these two proteins, as well as impairment in the nuclear localization of TBX5. These defects are likely central to the pathogenesis of Holt-Oram syndrome.

Our previous genomewide linkage scan of 428 nuclear families (GeneQuest) identified a significant genetic susceptibility locus for premature myocardial infarction (MI) on chromosome 1p34-36. We analyzed candidate genes in the locus with a population-based association study involving probands with premature coronary artery disease (CAD) and/or MI from the GeneQuest families (381 cases) and 560 controls without stenosis detectable by coronary angiography. A nonconservative substitution, R952Q, in LRP8 was significantly associated with susceptibility to premature CAD and/or MI by use of both population-based and family-based designs. Three additional white populations were used for follow-up replication studies: another independent cohort of CAD- and/or MI-affected families (GeneQuest II: 441 individuals from 22 pedigrees), an Italian cohort with familial MI (248 cases) and 308 Italian controls, and a separate Cleveland GeneBank cohort with sporadic MI (1,231 cases) and 560 controls. The association was significantly replicated in two independent populations with a family history of CAD and/or MI, the GeneQuest II family-based replication cohort and the Italian cohort, but not in the population with sporadic disease. The R952Q variant of LRP8 increased activation of p38 mitogen-activated protein kinase by oxidized low-density lipoprotein. This extensive study, involving multiple independent populations, provides the first evidence that genetic variants in LRP8 may contribute to the development of premature and familial CAD and MI.

Coronary artery disease (CAD), including its most serious complication myocardial infraction (MI), is the leading cause of death in the US and developed countries. We recently discovered that a seven-amino acid deletion in MEF2A, a transcription factor with a high level of expression in the endothelium of coronary arteries, co-segregates with CAD/MI in one family, and it suppresses transcription activation activity of MEF2A by a dominant-negative mechanism. In this study, we used single-strand conformation polymorphism and DNA sequence analyses to identify mutations in MEF2A in 207 independent CAD/MI patients and 191 controls with normal angiograms. We identified three novel mutations in exon 7 of MEF2A in four of 207 CAD/MI patients (1.93%). No mutations were detected in the 191 controls. The mutations identified here include N263S identified in two independent CAD patients, P279L in one patient and his father with the diagnosis of CAD and G283D in one patient. These mutations are clustered within or close to the major transcriptional activation domain of MEF2A. They significantly reduce the transcriptional activation activity of MEF2A and act by a loss-of-function mechanism. The gene carriers with loss-of-function mutations appear to be associated with less severe CAD. These results suggest that CAD/MI can result from a spectrum of MEF2A transcription dysfunctions ranging from loss-of-function to dominant-negative suppression and that a significant percent of the CAD/MI population (1.93%) may carry mutations in MEF2A, although further definition of the prevalence of MEF2A mutations is warranted.

AGGF1 is an angiogenic factor, and its deregulation is associated with a vascular malformation consistent with KlippelTrenaunay syndrome (KTS). This study defines the molecular mechanism for transcriptional regulation of AGGF1 expression. Transcription of AGGF1 starts at two nearby sites, ؊367 and ؊364 bp upstream of the translation start site. Analyses of 5-and 3-serial promoter deletions defined the core promoter/regulatory elements, including two repressor sites (from ؊1971 to ؊3990 and from ؊7521 to ؊8391, respectively) and two activator sites (a GATA1 consensus binding site from ؊295 to ؊300 and a second activator site from ؊129 to ؊159). Both the GATA1 site and the second activator site are essential for AGGF1 expression. A similar expression profile was found for GATA1 and AGGF1 in cells (including various endothelial cells) and tissues. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that GATA1 was able to bind to the AGGF1 DNA in vitro and in vivo. Overexpression of GATA1 increased expression of AGGF1. We identified one rare polymorphism ؊294C>T in a sporadic KTS patient, which is located in the GATA1 site, disrupts binding of GATA1 to DNA, and abolishes the GATA1 stimulatory effect on transcription of AGGF1. Knockdown of GATA1 expression by siRNA reduced expression of AGGF1, and resulted in endothelial cell apoptosis and inhibition of endothelial capillary vessel formation and cell migration, which was rescued by purified recombinant human AGGF1 protein. These results demonstrate that GATA1 regulates expression of AGGF1 and reveal a novel role for GATA1 in endothelial cell biology and angiogenesis.The AGGF1 gene, previously known as VG5Q, encodes an angiogenic factor with 714 amino acid residues (1). AGGF1 was identified through genetic analysis of Klippel-Trenaunay syndrome (KTS, MIM #149000), 2 which is a congenital vascular disorder composed of capillary malformations, venous malformations or varicose veins, and hypertrophy of the affected tissues (2-5). KTS is a congenital disorder, but most cases are sporadic. The genetic basis of KTS is complex and may involve multiple genes, environmental factors, and their interactions (6). To date, identification of susceptibility genes associated with KTS has relied upon gross cytogenetic defects reported in KTS patients. Three chromosomal abnormalities have been identified in three separate KTS patients: two balanced translocations t(5.11)(q13.3;p15.1) and t(8,14)(q22.3;q13), and an extra supernumerary ring chromosome 18 (7-9). Chromosomal breakpoints involved in KTS translocation t(5;11)(q13.3; p15.1) have been fully characterized. No gene has been identified within a 100-kb region flanking the chromosome 11p15.1 translocation breakpoint. In contrast, the chromosome 5p13.3 breakpoint is located in the promoter/regulatory region of the AGGF1 gene and leads to increased transcriptional activation of AGGF1 by 3-fold (1). The results suggest that deregulation of AGGF1 is associated with KTS. However, the molecular mech...

Background: Currently, women represent <25% of heart transplant recipients. Reasons for this female underrepresentation have been attributed to selection and referral bias and potentially poorer outcomes in female recipients. The aim of this study was to compare long-term posttransplant survival between men and women, when matched for recipient and donor characteristics. Methods and Results: Using the International Society for Heart and Lung Transplantation Registry, we performed descriptive analyses and estimated overall freedom from posttransplant death stratified by sex using Kaplan-Meier survival methods. Male and female recipients were matched according to the Index for Mortality Prediction After Cardiac Transplantation and Donor Risk Index score using 1:1 propensity score matching. The study cohort comprised 34 198 heart transplant recipients (76.3% men, 23.7% women) between 2004 and 2014. Compared with men, women were more likely younger (51 [39–59] versus 55 [46–61] years; P <0.001) and had a different distribution of heart failure etiology ( P <0.001). In general, the prevalence of comorbidities was lower in women than in men. Women were less likely to have diabetes mellitus (19.1% versus 26.2%; P <0.001), hypertension (40.7% versus 47.9%; P <0.001), peripheral vascular disease (2.4% versus 3.3%; P =0.002), tobacco use (36.5% versus 52.3%; P <0.001), and prior cardiovascular surgery (38.6% versus 50.7%; P <0.001). Women were more likely to have a history of malignancy (10.5% versus 5.3%; P <0.001), require intravenous inotropes (41.4% versus 37.2%; P <0.001), and were less likely supported by an intra-aortic balloon pump (3.3% versus 3.8%; P =0.03) or durable ventricular assist device (22% versus 31.5%; P <0.001). Transplanted male recipients had a higher Index for Mortality Prediction After Cardiac Transplantation score (5 [2–7] versus 4 [1–6]; P <0.001). When male and female heart transplant recipients were matched for recipient and donor characteristics, there was no significant survival difference ( P =0.57). Conclusions: Overall survival does not differ between men and women after cardiac transplantation. Women who survive to heart transplantation appear to have lower risk features than male recipients but receive hearts from higher risk donors.