Identification of BMP10 as a Novel Gene Contributing to Dilated Cardiomyopathy.

Dilated cardiomyopathy (DCM), characterized by left ventricular or biventricular enlargement with systolic dysfunction, is the most common type of cardiac muscle disease. It is a major cause of congestive heart failure and the most frequent indication for heart transplantation. Aggregating evidence has convincingly demonstrated that DCM has an underlying genetic basis, though the genetic defects responsible for DCM in a larger proportion of cases remain elusive, motivating the ongoing research for new DCM-causative genes. In the current investigation, a multigenerational family affected with autosomal-dominant DCM was recruited from the Chinese Han population. By whole-exome sequencing and Sanger sequencing analyses of the DNAs from the family members, a new BMP10 variation, NM_014482.3:c.166C > T;p.(Gln56*), was discovered and verified to be in co-segregation with the DCM phenotype in the entire family. The heterozygous BMP10 variant was not detected in 268 healthy volunteers enrolled as control subjects. The functional measurement via dual-luciferase reporter assay revealed that Gln56*-mutant BMP10 lost the ability to transactivate its target genes NKX2.5 and TBX20, two genes that had been causally linked to DCM. The findings strongly indicate BMP10 as a new gene contributing to DCM in humans and support BMP10 haploinsufficiency as an alternative pathogenic mechanism underpinning DCM, implying potential implications for the early genetic diagnosis and precision prophylaxis of DCM.

VEZF1 loss-of-function mutation underlying familial dilated cardiomyopathy.

Dilated cardiomyopathy (DCM), characteristic of left ventricular or biventricular dilation with systolic dysfunction, is the most common form of cardiomyopathy, and a leading cause of heart failure and sudden cardiac death. Aggregating evidence highlights the underlying genetic basis of DCM, and mutations in over 100 genes have been causally linked to DCM. Nevertheless, due to pronounced genetic heterogeneity, the genetic defects underpinning DCM in most cases remain obscure. Hence, this study was sought to identify novel genetic determinants of DCM. In this investigation, whole-exome sequencing and bioinformatics analyses were conducted in a family suffering from DCM, and a novel heterozygous mutation in the VEZF1 gene (coding for a zinc finger-containing transcription factor critical for cardiovascular development and structural remodeling), NM_007146.3: c.490A > T; p.(Lys164*), was identified. The nonsense mutation was validated by Sanger sequencing and segregated with autosome-dominant DCM in the family with complete penetrance. The mutation was neither detected in another cohort of 200 unrelated DCM patients nor observed in 400 unrelated healthy individuals nor retrieved in the Single Nucleotide Polymorphism database, the Human Gene Mutation Database and the Genome Aggregation Database. Biological analyses by utilizing a dual-luciferase reporter assay system revealed that the mutant VEZF1 protein failed to transactivate the promoters of MYH7 and ET1, two genes that have been associated with DCM. The findings indicate VEZF1 as a new gene responsible for DCM, which provides novel insight into the molecular pathogenesis of DCM, implying potential implications for personalized precisive medical management of the patients affected with DCM.

PRRX1 Loss-of-Function Mutations Underlying Familial Atrial Fibrillation.

Background Atrial fibrillation (AF) is the most common form of clinical cardiac dysrhythmia responsible for thromboembolic cerebral stroke, congestive heart failure, and death. Aggregating evidence highlights the strong genetic basis of AF. Nevertheless, AF is of pronounced genetic heterogeneity, and in an overwhelming majority of patients, the genetic determinants underpinning AF remain elusive. Methods and Results By genome-wide screening with polymorphic microsatellite markers and linkage analysis in a 4-generation Chinese family affected with autosomal-dominant AF, a novel locus for AF was mapped to chromosome 1q24.2-q25.1, a 3.20-cM (≈4.19 Mbp) interval between markers D1S2851 and D1S218, with the greatest 2-point logarithm of odds score of 4.8165 for the marker D1S452 at recombination fraction=0.00. Whole-exome sequencing and bioinformatics analyses showed that within the mapping region, only the mutation in the paired related homeobox 1 (PRRX1) gene, NM_022716.4:c.319C>T;(p.Gln107*), cosegregated with AF in the family. In addition, sequencing analyses of PRRX1 in another cohort of 225 unrelated patients with AF revealed a new mutation, NM_022716.4:c.437G>T; (p.Arg146Ile), in a patient. The 2 mutations were absent in 908 control subjects. Biological analyses in HeLa cells demonstrated that the 2 mutants had significantly diminished transactivation on the target genes ISL1 and SHOX2 and markedly decreased ability to bind the promoters of ISL1 and SHOX2 (2 genes causally linked to AF), although with normal intracellular distribution. Conclusions This study first indicates that PRRX1 loss-of-function mutations predispose to AF, which provides novel insight into the molecular pathogenesis underpinning AF, implying potential implications for precisive prophylaxis and management of AF.

Atrial Arrhythmias in Patients with Severe COVID-19.

The number of confirmed COVID-19 cases has increased drastically; however, information regarding the impact of this disease on the occurrence of arrhythmias is scarce. The aim of this study was to determine the impact of COVID-19 on arrhythmia occurrence. This prospective study included patients with COVID-19 treated at the Leishenshan Temporary Hospital of Wuhan City, China, from February 24 to April 5, 2020. Demographic, comorbidity, and arrhythmias data were collected from patients with COVID-19 (n = 84) and compared with control data from patients with bacterial pneumonia (n = 84) infection. Furthermore, comparisons were made between patients with severe and nonsevere COVID-19 and between older and younger patients. Compared with patients with bacterial pneumonia, those with COVID-19 had higher total, mean, and minimum heart rates (all P < 0.01). Patients with severe COVID-19 (severe and critical type diseases) developed more atrial arrhythmias compared with those with nonsevere symptoms. Plasma creatine kinase isoenzyme (CKMB) levels (P=0.01) were higher in the severe group than in the nonsevere group, and there were more deaths in the severe group than in the nonsevere group (6 (15%) vs. 3 (2.30%); P=0.05). Premature atrial contractions (PAC) and nonsustained atrial tachycardia (NSAT) were significantly positively correlated with plasma CKMB levels but not with high-sensitive cardiac troponin I or myoglobin levels. Our data demonstrate that COVID-19 patients have higher total, mean, and minimum heart rates compared with those with bacterial pneumonia. Patients with severe or critical disease had more frequent atrial arrhythmias (including PAC and AF) and higher CKMB levels and mortality than those with nonsevere symptoms.

Identification and functional characterization of KLF5 as a novel disease gene responsible for familial dilated cardiomyopathy.

As a prevalent primary myocardial disease, dilated cardiomyopathy (DCM) represents the most common cause of heart failure in the young and the most frequent indication for cardiac transplantation. Aggregating evidence highlights the genetic basis of DCM. However, due to substantial genetic heterogeneity, the genetic defects of DCM in most cases remain elusive. In the current investigation, the entire coding exons and splicing junctions of the KLF5 gene, which encodes a key transcription factor required for cardiac structural and functional remodeling, were sequenced in 234 probands affected with DCM, and a heterozygous KLF5 mutation, NM_001730.5: c.1100T > A; p.(Leu367*), was identified in a proband. Genetic analysis of the proband's family members revealed that the identified KLF5 mutation co-segregated with DCM in the family with complete penetrance. The nonsense mutation was neither detected in 506 control individuals nor reported in such population-genetics databases as ExAC, dbSNP and gnomAD. Biological assays with a dual-luciferase reporter assay system demonstrated that the mutant KLF5 protein had no transcriptional activity when compared with its wild-type counterpart. Furthermore, the mutation abrogated the synergistic transactivation between KLF5 and NFKB1, another pivotal transcription factor that has been causally linked to DCM. The whole-exome sequencing analysis of the proband's family members revealed no other causative genes. The findings indicate KLF5 as a new gene contributing to DCM in humans, implying potential implications for the precision medicine of DCM.

NR2F2 loss­of­function mutation is responsible for congenital bicuspid aortic valve.

Congenital bicuspid aortic valve (BAV) represents the most common type of cardiac birth defect affecting 0.4­2% of the general population, and accounts for a markedly increased incidence of life­threatening complications, including valvulopathy and aortopathy. Accumulating evidence has demonstrated the genetic basis of BAV. However, the genetic basis for BAV in the majority of cases remains to be elucidated. In the present study, the coding regions and splicing donors/acceptors of the nuclear receptor subfamily 2 group F member 2 (NR2F2) gene, which encodes a transcription factor essential for proper cardiovascular development, were sequenced in 176 unrelated cases of congenital BAV. The available family members of the proband carrying an identified NR2F2 mutation and 280 unrelated, sex­ and ethnicity­matched healthy individuals as controls were additionally genotyped for NR2F2. The functional effect of the mutation was characterized using a dual­luciferase reporter assay system. As a result, a novel heterozygous NR2F2 mutation, NM_021005.3: c.288C>A; p.(Cys96*), was identified in a family with BAV, which was transmitted in an autosomal dominant mode with complete penetrance. The nonsense mutation was absent from the 560 control chromosomes. Functional analysis identified that the mutant NR2F2 protein had no transcriptional activity. Furthermore, the mutation disrupted the synergistic transcriptional activation between NR2F2 and transcription factor GATA­4, another transcription factor that is associated with BAV. These findings suggested NR2F2 as a novel susceptibility gene of human BAV, which reveals a novel molecular pathogenesis underpinning BAV.

HAND2 loss-of-function mutation causes familial dilated cardiomyopathy.

As two members of the basic helix-loop-helix family of transcription factors, HAND1 and HAND2 are both required for the embryonic cardiogenesis and postnatal ventricular structural remodeling. Recently a HAND1 mutation has been reported to cause dilated cardiomyopathy (DCM). However, the association of a HAND2 mutation with DCM is still to be ascertained. In this research, the coding regions and splicing junction sites of the HAND2 gene were sequenced in 206 unrelated patients affected with idiopathic DCM, and a new heterozygous HAND2 mutation, NM_021973.2: c.199G > T; p.(Glu67*), was discovered in an index patient with DCM. The nonsense mutation was absent in 300 unrelated, ethnically-matched healthy persons. Genetic scan of the mutation carrier's family members revealed that the genetic mutation co-segregated with DCM, which was transmitted in an autosomal dominant fashion, with complete penetrance. Functional deciphers unveiled that the mutant HAND2 protein had no transcriptional activity. In addition, the mutation abrogated the synergistic transcriptional activation between HAND2 and GATA4 or between HAND2 and NKX2.5, two other cardiac transcription factors that have been implicated in DCM. These research findings firstly suggest HAND2 as a novel gene predisposing to DCM in humans, which adds novel insight to the molecular pathogenesis of DCM, implying potential implications in the design of personized preventive and therapeutic strategies against DCM.

ISL1 loss-of-function mutation contributes to congenital heart defects.

Congenital heart defect (CHD) is the most common form of birth deformity and is responsible for substantial morbidity and mortality in humans. Increasing evidence has convincingly demonstrated that genetic defects play a pivotal role in the pathogenesis of CHD. However, CHD is a genetically heterogeneous disorder and the genetic basis underpinning CHD in the vast majority of cases remains elusive. This study was sought to identify the pathogenic mutation in the ISL1 gene contributing to CHD. A cohort of 210 unrelated patients with CHD and a total of 256 unrelated healthy individuals used as controls were registered. The coding exons and splicing boundaries of ISL1 were sequenced in all study subjects. The functional effect of an identified ISL1 mutation was evaluated using a dual-luciferase reporter assay system. A novel heterozygous ISL1 mutation, c.409G > T or p.E137X, was identified in an index patient with congenital patent ductus arteriosus and ventricular septal defect. Analysis of the proband's pedigree revealed that the mutation co-segregated with CHD, which was transmitted in the family in an autosomal dominant pattern with complete penetrance. The nonsense mutation was absent in 512 control chromosomes. Functional analysis unveiled that the mutant ISL1 protein failed to transactivate the promoter of MEF2C, alone or in synergy with TBX20. This study firstly implicates ISL1 loss-of-function mutation with CHD in humans, which provides novel insight into the molecular mechanism of CHD, implying potential implications for genetic counseling and individually tailored treatment of CHD patients.

Identification and Functional Characterization of an ISL1 Mutation Predisposing to Dilated Cardiomyopathy.

Dilated cardiomyopathy (DCM) is the most prevalent cause of non-ischemic cardiac failure and the commonest indication for cardiac transplantation. Compelling evidence highlights the pivotal roles of genetic defects in the occurrence of DCM. Nevertheless, the genetic determinants underpinning DCM remain largely obscure. In this study, the coding regions of ISL1, which encodes a transcription factor critical for embryonic cardiogenesis and postnatal cardiac remodeling, were sequenced in 216 unrelated patients with DCM, and a novel heterozygous ISL1 mutation, NM_002202.2: c.631A>T; p.(Lys211*), was identified in a proband. The mutation, which co-segregated with DCM in the family, was absent in 238 unrelated controls, as well as in the Genome Aggregation and the Exome Aggregation Consortium population databases. Functional analyses unveiled that the mutant ISL1 protein lost transcriptional activity alone or in synergy with TBX20 or GATA4, two other transcription factors associated with DCM. These findings indicate ISL1 as a new gene of DCM.

A SHOX2 loss-of-function mutation underlying familial atrial fibrillation.

Atrial fibrillation (AF), as the most common sustained cardiac arrhythmia, is associated with substantially increased morbidity and mortality. Aggregating evidence demonstrates that genetic defects play a crucial role in the pathogenesis of AF, especially in familial AF. Nevertheless, AF is of pronounced genetic heterogeneity, and in an overwhelming majority of cases the genetic determinants underlying AF remain elusive. In the current study, 162 unrelated patients with familial AF and 238 unrelated healthy individuals served as controls were recruited. The coding exons and splicing junction sites of the SHOX2 gene, which encodes a homeobox-containing transcription factor essential for proper development and function of the cardiac conduction system, were sequenced in all study participants. The functional effect of the mutant SHOX2 protein was characterized with a dual-luciferase reporter assay system. As a result, a novel heterozygous SHOX2 mutation, c.580C>T or p.R194X, was identified in an index patient, which was absent from the 476 control chromosomes. Genetic analysis of the proband's pedigree revealed that the nonsense mutation co-segregated with AF in the family with complete penetrance. Functional assays demonstrated that the mutant SHOX2 protein had no transcriptional activity compared with its wild-type counterpart. In conclusion, this is the first report on the association of SHOX2 loss-of-function mutation with enhanced susceptibility to familial AF, which provides novel insight into the molecular mechanism underpinning AF, suggesting potential implications for genetic counseling and individualized management of AF patients.

GATA6 loss-of-function mutation contributes to congenital bicuspid aortic valve.

Congenital bicuspid aortic valve (BAV), the most common form of birth defect in humans, is associated with substantial morbidity and mortality. Increasing evidence demonstrates that genetic risk factors play a key role in the pathogenesis of BAV. However, BAV is a genetically heterogeneous disease and the genetic determinants underpinning BAV in an overwhelming majority of patients remain unknown. In the present study, the coding exons and flanking introns of the GATA6 gene, which encodes a zinc-finger transcription factor essential for the normal development of the aortic valves, were sequenced in 152 unrelated patients with congenital BAV. The available relatives of a proband harboring an identified GATA6 mutation and 200 unrelated, ethnically matched healthy individuals used as controls were also genotyped for GATA6. The functional characteristics of the mutation were analyzed by using a dual-luciferase reporter assay system. As a result, a novel heterozygous GATA6 mutation, p.E386X, was identified in a family with BAV transmitted in an autosomal dominant mode. The nonsense mutation was absent in 400 control chromosomes. Biological assays revealed that the mutant GATA6 protein had no transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation disrupted the synergistic transcriptional activation between GATA6 and GATA4, another transcription factor causally linked to BAV. In conclusion, this study firstly associates GATA6 loss-of-function mutation with enhanced susceptibility to familial BAV, which provides novel insight into the molecular mechanism of BAV, implying potential implications for genetic counseling and personalized management of BAV patients.

[Efficacy and safety of ambrisentan therapy in Chinese patients with pulmonary hypertension].

OBJECTIVE: To explore the efficacy, safety and tolerance of ambrisentan, a high-selective endothelin receptor antagonist, in Chinese patients with pulmonary hypertension (PH). METHODS: Twenty-eight PH patients (Group 1+Group 4) came from Shanghai East Hospital, Zhongshan Hospital of Fudan University and Fifth People's Hospital of Shanghai were recruited into this open-label, prospective multi-center trial between August 2012 and February 2013. They received 2.5-5.0 mg ambrisentan once daily for 12 weeks. The primary endpoint was the change in exercise capacity showed by six-minute walk distance (6MWD) from baseline to 12 weeks. Secondary endpoints included the changes in World Health Organization (WHO) function class, N-terminal brain natriuretic peptide (NT-proBNP) and liver function test results. RESULTS: There were 9 males and 19 females with an average age of (35 ± 17) years. The value of 6MWD increased from (372 ± 86) m at baseline to (443 ± 96) m (P = 0.000) after 12 weeks. WHO functional class improved after a 12-week therapy compared to the baseline level (P = 0.000). NT-proBNP decreased from a median of 732 ng/L at baseline to 329 ng/L after 12 weeks (P = 0.046). The baseline liver function test was normal. And liver function test didn't significantly change after a 12-week therapy. CONCLUSION: Ambrisentan therapy is well-tolerated and it improves the exercise capacity and WHO function class in Chinese PH patients.

Serum high-density lipoprotein cholesterol levels as a prognostic indicator in patients with idiopathic pulmonary arterial hypertension.

High-density lipoprotein (HDL) cholesterol levels are a strong, independent inverse predictor of cardiovascular disease. The present study aimed to determine whether serum HDL cholesterol levels correlated with disease severity and clinical outcomes in patients with idiopathic pulmonary arterial hypertension (IPAH). The serum HDL cholesterol levels were measured in 76 Chinese patients with IPAH and 45 healthy controls, together with other clinical variables. Univariate and multivariate Cox proportional hazards analysis was performed to assess the prognostic value of HDL cholesterol and event-free survival. Event-free survival was estimated using the Kaplan-Meier method. Serum HDL cholesterol levels were significantly decreased in patients with IPAH compared with controls (1.0 ± 0.3 vs 1.5 ± 0.3 mmol/L; p <0.001). The serum HDL cholesterol levels decreased in proportion to the severity of World Health Organization functional class. Compared to the high HDL cholesterol group, the low HDL cholesterol group demonstrated a significantly lower 6-minute walking distance, cardiac index, mixed venous saturation, and arterial carbon dioxide pressure but significantly greater pulmonary vascular resistance and serum uric acid levels. The serum HDL cholesterol levels correlated positively with the cardiac index (r = 0.42; p = 0.002) and negatively with the pulmonary vascular resistance (r = -0.25; p = 0.04). Serum HDL cholesterol was independently related to event-free survival on multivariate Cox proportional hazards analysis. Kaplan-Meier survival curves according to the median HDL cholesterol value showed that lower HDL cholesterol levels were associated with lower event-free survival. In conclusion, serum HDL cholesterol levels might serve as an indicator of disease severity and prognosis in patients with IPAH.

[Clinical characteristics and survival of patients with pulmonary veno-occlusive disease].

OBJECTIVE: To investigate the clinical presentation, diagnosis, treatment and outcome of patients with pulmonary veno-occlusive disease (PVOD). METHODS: Data from patients diagnosed as PVOD from May 2008 to May 2011 in Shanghai Pulmonary Hospital, Tongji University were retrospectively reviewed. RESULTS: During this period, 5 patients [4 female, aged from 12 to 42 (22 ± 12) years old] were diagnosed as PVOD. The durations from symptoms onset to PVOD diagnosis was 2 to 50 (16 ± 20) months and four of them were previously diagnosed as idiopathic pulmonary arterial hypertension. All patients at the time of PVOD diagnosis had a severely impaired WHO pulmonary hypertension functional class (3 in class III and 2 in class IV). Furthermore, all patients characterized by a typical sign of centrilobular ground-glass opacities in high-resolution computed tomography, a markedly reduction of diffusing capacity of the lung for carbon monoxide [(38 ± 12)% of predicted value] in pulmonary functional test and severely compromised cardio-pulmonary hemodynamics identified by right heart catheterization. All patients received conventional and pulmonary arterial hypertension specific therapies, and then followed-up regularly. Up to now, 4 out of 5 patients died due to refractory right heart failure. The durations from symptoms onset to death and from PVOD establish to death were 5 - 65 (27 ± 26) months and 1 - 16 (9 ± 9) months, respectively. CONCLUSIONS: PVOD is a rare and malignant cardio-pulmonary disorder that often be misdiagnosed as idiopathic pulmonary arterial hypertension. Given the poor responses to modern pulmonary arterial hypertension specific therapies, lung transplantation remains the treatment of choice.

Increased stromal-cell-derived factor 1 enhances the homing of bone marrow derived mesenchymal stem cells in dilated cardiomyopathy in rats.

BACKGROUND: Stem cell transplantation has been shown to have beneficial effects on dilated cardiomyopathy. However, mechanism for stem cell homing to cardiac tissue in dilated cardiomyopathy has not yet been elucidated. METHODS: Mesenchymal stem cells were obtained from rat bone marrow, expanded in vitro, and labeled with (99m)Tc. Cardiomyopathy model was induced by doxorubicin in rats. (99m)Tc labeled cells were infused into the left ventricles in cardiomyopathy and control rats. Sixteen hours after injection, animals were sacrificed and different tissues were harvested to measure specific radioactivity. By use of real-time polymerase chain reaction and immunohistochemistry, mRNA and protein expressions for stromal-cell-derived factor 1 in cardiac tissue were measured. RESULTS: Labeling efficiency of mesenchymal stem cells was (70.0 ± 11.2)%. Sixteen hours after mesenchymal stem cell transplantation, the heart-to-muscle radioactivity ratio was increased significantly in cardiomyopathy hearts as compared to control hearts. Both mRNA and protein expressions of stromal-cell-derived factor 1 were up-regulated in cardiomyopathy hearts as compared with control hearts. CONCLUSION: In dilated cardiomyopathy induced by doxorubicin up-regulated expression of stromal-cell-derived factor 1 in heart may induce mesenchymal stem cells home to the heart.

PDK1 plays a critical role in regulating cardiac function in mice and human.

BACKGROUND: PDK1 is an essential protein kinase that plays a critical role in mammalian development. Mouse lacking PDK1 leads to multiple abnormalities and embryonic lethality at E9.5. To elucidate the role of PDK1 in the heart, we investigated the cardiac phenotype of mice that lack PDK1 in the heart in different growth periods and the alteration of PDK1 signaling in human failing heart. METHODS: We employed Cre/loxP system to generate PDK1(flox/flox): α-MHC-Cre mice, which specifically deleted PDK1 in cardiac muscle at birth, and tamoxifen-inducible heart-specific PDK1 knockout mice (PDK1(flox/flox):MerCreMer mice), in which PDK1 was deleted in myocardium in response to the treatment with tamoxifen. Transmural myocardial tissues from human failing hearts and normal hearts were sampled from the left ventricular apex to analyze the activity of PDK1/Akt signaling pathways by Western blotting. RESULTS: PDK1(flox/flox): α-MHC-Cre mice died of heart failure at 5 and 10 weeks old. PDK1(flox/flox) -MerCreMer mice died of heart failure from 5 to 21 weeks after the initiation of tamoxifen treatment at 8 weeks old. We found that expression levels of PDK1 in human failing heart tissues were significantly decreased compared with control hearts. CONCLUSION: Our results suggest that PDK1 signaling network takes part in regulating cardiac viability and function in mice, and may be also involved in human heart failure disease.