Novel SCN5A frame­shift mutation underlying in patient with idiopathic ventricular fibrillation manifested with J wave in inferior lead and prolonged S­wave in precordial lead.

Mutations in the SCN5A gene has been recognized as resulting in a series of life-threatening arrhythmias. However, it also causes idiopathic ventricular fibrillation (IVF) with J wave in inferior leads and prolonged S-wave upstroke in precordial leads, which has not been previously reported. The present study aimed to study the mechanisms of a patient with IVF manifested with J wave in inferior leads and prolonged S-wave upstroke in precordial leads. The electrocardiograms (ECG) of the proband were recorded and genetic testing was conducted. Patch-clamp and immunocytochemical studies were performed in heterologously transfected 293 cells. The VF attacks was documented in a 55-year-old male proband with syncope episodes. 12-lead ECG shown the transient J wave in the inferior leads and prolonged S-wave upstroke in precordial V1-V3 leads in the same timeframe. Genetic analysis revealed a novel 1 base deletion (G) at position 839 in exon 2 in SCN5A gene (C280S*fs61), which causes a severe truncation of the sodium channel. The functional study revealed that in 293 cells transfected with mutant channel, no sodium current could be recorded even though the immunocytochemical experiment confirmed the truncated sodium channel existed in cytosol. The kinetics of the wild-type (WT) channel were not altered when co-transfected with C280S*fs61 mutant which suggested a haploinsufficiency effect of sodium channel in the cells. The present study identified a novel C280Sfs*61 mutation that caused the 'loss of function' of the sodium channel by haploinsufficiency mechanism. The reduced sodium channel function in the heart may cause conduction delay that may underlie the manifestation of J wave and prolonged S-wave upstroke associated with IVF.

Genome-Wide Association Study for Idiopathic Ventricular Tachyarrhythmias Identifies Key Role of CCR7 and PKN2 in Calcium Homeostasis and Cardiac Rhythm Maintenance.

BACKGROUND: Idiopathic ventricular tachycardia (VT) occurs in structurally normal hearts and accounts for a significant number of all types of VT. The genome-wide association study is the most effective strategy for identifying novel genetic variants for common diseases. However, no genome-wide association study has been reported for idiopathic VT. METHODS: We conducted the first genome-wide association study for idiopathic VT in the Chinese Han population using a discovery population with 246 cases and 648 controls and a replication population with 222 cases and >4072 controls. Candidate VT genes were functionally characterized in zebrafish. Real-time RT-PCR analysis was used to determine the effects of candidate genes on expression of ion channels and regulators. Patch-clamping was used to record L-type calcium current from neonatal rat cardiomyocytes with overexpression of candidate genes. RESULTS: We identified 4 significant loci represented by rs78960694 (minor allele frequency [MAF]=5.02% in cases and 1.84% in controls; P=4.30×10-12, odds ratio [OR]=3.91) and rs2229095 (MAF=3.25% in cases and 1.63% in controls; P=1.02×10-7, OR=3.44) near and in CCR7, respectively, rs68126098 in NELL1 (MAF=40.98% in cases and 32.07% in controls; P=2.40×10-8, OR=1.53), rs2390325 between PKN2 and LMO4 (MAF=21.19% in cases and 15.12% in controls; P=1.92×10-7, OR=1.62), and rs270065 in CSMD1 (MAF=33.63% in cases and 40.25% in controls; P=9.51×10-7, OR=0.69). Note that the associations of idiopathic VT for CCR7 variant rs78960694 and NELL1 variant rs68126098 reach genome-wide significance (P<5.00×10-8). Overexpression of either PKN2 or CCR7 increased the heart rate in zebrafish, and enhanced expression of CACNA1C, RYR2, or NOS1AP in zebrafish embryos, HEK293, and AC16 cardiomyocytes. Overexpression of either PKN2 or CCR7 significantly increased L-type Ca2+ current density. CONCLUSIONS: The first genome-wide association study identifies 4 novel loci and 2 risk genes (PKN2 and CCR7) for idiopathic VT. These findings identify new molecular determinants for cardiac calcium homeostasis and rhythm maintenance and provide novel targets for diagnosis and treatment for idiopathic VT.

CMR Characteristics, gene variants and long-term outcome in patients with left ventricular non-compaction cardiomyopathy.

BACKGROUND: As the paucity of data focusing on evaluating cardiac structure and function in patients with or without gene mutation, this study was sought to investigate the correlation between genotype and cardiac magnetic resonance (CMR) phenotype in patients with left ventricular non-compaction cardiomyopathy (LVNC) and to explore prognostic relevance in this cohort if possible. METHODS: Patients with LVNC who underwent CMR and targeted gene sequencing between 2006 and 2016 were retrospectively evaluated. Demographic data, clinical presentation, genetic analysis, CMR data and follow-up data of all participants were collected. RESULTS: Compared to negative genotype (G-) group, patients with positive genotype (G+) had larger left atrial volume (LAV), and carriers of multiple variants had lower left ventricular (LV) ejection fraction and cardiac index, increased LV fibrosis, larger LA volume, reduced LV global circumferential strain, LA reservoir strain and booster pump strain (all p < 0.05). LA volume was able to discriminate patients with G + (all p < 0.05), as well as those with multiple genetic mutation (all p < 0.01). During a median follow-up of 5.1 years, Kaplan-Meier survival analysis revealed worse primary endpoint-free survival among carriers of multiple variants compared to G- group. CONCLUSIONS: CMR feature tracking is a remarkable tool to evaluate implication, genetics cascade screen and predict outcome in LVNC population. LA volume is a sensitive and robust indicator for genetic mutational condition, of which facilities to guide clinical management and intensity of follow-up for patients and their relatives.

LRP6 Polymorphisms Is Associated With Sudden Cardiac Death in Patients With Chronic Heart Failure in the Chinese Han Population.

Low-density lipoprotein receptor-related protein 6 (LRP6) plays a critical role in cardiovascular homeostasis. The deficiency of LRP6 is associated with a high risk of arrhythmias. However, the association between genetic variations of LRP6 and sudden cardiac death (SCD) remains unknown. This study aims to explore the association between common variants of LRP6 and the prognosis of chronic heart failure (CHF) patients. From July 2005 to December 2009, patients with CHF were enrolled from 10 hospitals in China. The single-nucleotide polymorphism (SNP) rs2302684 was selected for the evaluation of the effect of LRP6 polymorphisms on the survival in patients with CHF. A total of 1,437 patients with CHF were finally included for the analysis. During a median follow-up of 61 months (range 0.4-129 months), a total of 546 (38.0%) patients died, including 201 (36.8%) cases with SCD and 345 (63.2%) cases with non-SCD. Patients carrying A allele of rs2302684 had an increased risk of all-cause death (adjusted HR 1.452, 95% CI 1.189-1.706; P < 0.001) and SCD (adjusted HR 1.783, 95% CI 1.337-2.378; P < 0.001). Therefore, the SNP rs2302684 T>A in LRP6 indicated higher risks of all-cause death and SCD in patients with CHF. LRP6 could be added as a novel predictor of SCD and might be a potential therapeutic target in the prevention of SCD in the CHF population.

Stop codons and the +4 nucleotide may influence the efficiency of G418 in rescuing nonsense mutations of the HERG gene.

The importance of the local sequence context in determining how efficiently aminoglycosides rescue nonsense mutations has been established previously in disease models. Different stop codons appear to facilitate the termination process with differing efficiencies. Furthermore, the efficiency with which termination is suppressed may also be influenced by the local sequence context surrounding the stop codon. The strongest bias has usually been identified with the nucleotide base that immediately follows the stop codon in the majority of experiments. However, how the sequence context influences the efficiency of aminoglycosides in rescuing the human ether­a­go­go­related (HERG) protein in mammalian cells remains to be fully elucidated. Therefore, the present study was devised to examine the susceptibility of different termination codons on the HERG gene and the +4 nucleotide immediately following them to be suppressed by aminoglycosides in 293 cells. The 293 cells were transiently transfected with the wild­type or mutant genes. The read­through effect was subsequently examined by adding aminoglycoside G418 into the culture medium, followed by incubation of the cells for 24 h. An immunofluorescence method was then used to observe the protein expression of HERG prior to and following drug treatment. Patch clamping was performed to evaluate the function of the HERG protein. These experiments revealed that stop codons TGA and TAA in the R1014X mutant were more susceptible to treatment with the drug G418. Similar results were observed with the W927X­TGA and W927X­TAA mutants. Subsequently, R1014X­TGAC, R1014X­TGAG and R1014X­TGAA mutants were constructed based on the R1014X­TGAT mutant. The level of red fluorescence was observed prior to and following the administration of G418 using antibodies targeting the N­ or C­terminus of the HERG protein. However, the tail current density was found only to increase with the R1014X­TGAT mutant following G418 treatment. Taken together, the results of the present study suggest that the type of premature stop codon and the context of the nucleotide immediately following at the +4 position, may determine the pharmacological rescue efficiency of the HERG gene.

Clinical implications of sarcomere and nonsarcomere gene variants in patients with left ventricular noncompaction cardiomyopathy.

BACKGROUND: Robust data regarding genotype-phenotype correlations in left ventricular noncompaction cardiomyopathy (LVNC) are lacking. METHODS: About 72 cardiomyopathy-related genes were comprehensively screened in a cohort of LVNC patients using targeted sequencing. Baseline and follow-up data were collected. The primary endpoint was a composite of death and heart transplantation. RESULTS: A total of 83 unrelated adult patients were included in analyses. Following stringent classification according to the American College of Medical Genetics and Genomics (ACMG) guidelines, 36 pathogenic variants of 14 genes were detected in 32 patients. Among them, 12 patients carried at least one nonsarcomere variant (NSV). At baseline, NSV carriers had a higher frequency of atrial fibrillation, but lower left ventricular ejection fraction, than did noncarriers. During a median follow-up of 4.2 years, NSV carriers experienced a higher rate of the primary endpoint compared with noncarriers. There was no significant difference in the rate between carriers of sarcomere variant (SV) and noncarriers, as well as between carriers of SV and NSV. The presence of NSV was associated with an increased risk of the primary endpoint independent of age, sex, and cardiac function (hazard ratio: 3.61, 95% confidence interval: 1.42-9.19, p = .002). CONCLUSION: NSV may act as a genetic modifier and worsen the clinical phenotype in patients with LVNC.

Identification of rare variants in cardiac sodium channel ß4-subunit gene SCN4B associated with ventricular tachycardia.

Ventricular tachycardia (VT) causes sudden cardiac death, however, the majority of risk genes for VT remain unknown. SCN4B encodes a ß-subunit, Navß4, for the voltage-gated cardiac sodium channel complex involved in generation and conduction of the cardiac action potential. We hypothesized that genomic variants in SCN4B increase the risk of VT. We used high-resolution melt analysis followed by Sanger sequencing to screen 199 VT patients to identify nonsynonymous variants in SCN4B. Two nonsynonymous heterozygous variants in SCN4B were identified in VT patients, including p.Gly8Ser in four VT patients and p.Ala145Ser in one VT patient. Case-control association studies were used to assess the association between variant p.Gly8Ser and VT in two independent populations for VT (299 VT cases vs. 981 controls in population 1 and 270 VT patients vs. 639 controls in population 2). Significant association was identified between p.Gly8Ser and VT in population 1 (P = 1.21 × 10-4, odds ratio or OR = 11.04), and the finding was confirmed in population 2 (P = 0.03, OR = 3.62). The association remained highly significant in the combined population (P = 3.09 × 10-5, OR = 6.17). Significant association was also identified between p.Gly8Ser and idiopathic VT (P = 1.89 × 10-5, OR = 7.27). Functional analysis with Western blotting showed that both p.Gly8Ser and p.Ala145Ser variants significantly reduced the expression level of Navß4. Based on 2015 ACMG Standards and Guidelines, p.Gly8Ser and p.Ala145Ser can be classified as the pathogenic and likely pathogenic variant, respectively. Our data suggest that SCN4B is a susceptibility gene for common VT and idiopathic VT and link rare SCN4B variants with large effects (OR = 6.17-7.27) to common VT.

Titin-truncating variants are associated with heart failure events in patients with left ventricular non-compaction cardiomyopathy.

BACKGROUND: Titin-truncating variants (TTNtv) have been recognized as the most prevalent genetic cause of dilated cardiomyopathy. However, their effects on phenotypes of left ventricular non-compaction cardiomyopathy (LVNC) remain largely unknown. HYPOTHESIS: The presence of TTNtv may have an effect on the phenotype of LVNC. METHODS: TTN was comprehensively screened by targeted sequencing in a cohort of 83 adult patients with LVNC. Baseline and follow-up data of all participants were collected. The primary endpoint was a composite of death and heart transplantation. The secondary endpoint was heart failure (HF) events, a composite of HF-related death, heart transplantation, and HF hospitalization. RESULTS: Overall, 13 TTNtv were identified in 13 patients, with 9 TTNtv located in the A-band of titin. There was no significant difference in baseline characteristics between patients with and without TTNtv. During a median follow-up of 4.4 years, no significant difference in death and heart transplantation between the two groups was observed. However, more HF events occurred in TTNtv carriers than in non-carriers (P = 0.006). Multivariable analyses showed that TTNtv were associated with an increased risk of HF events independent of sex, age, and baseline cardiac function (hazard ratio: 3.25, 95% confidence interval: 1.50-7.01, P = 0.003). Sensitivity analysis excluding non-A-band TTNtv yielded similar results, but with less strength. CONCLUSIONS: The presence of TTNtv may be a genetic modifier of LVNC and confer a higher risk of HF events among adult patients. Studies of larger cohorts are needed to confirm our findings.

Genotype-Positive Status Is Associated With Poor Prognoses in Patients With Left Ventricular Noncompaction Cardiomyopathy.

Background Left ventricular noncompaction cardiomyopathy ( LVNC ) is a genetically and phenotypically heterogeneous disease. This study aims to investigate the genetic basis and genotype-phenotype correlations in a cohort of Chinese patients with LVNC . Methods and Results A total of 72 cardiomyopathy-associated genes were comprehensively screened in 83 adults and 17 children with LVNC by targeted sequencing. Pathogenicity of the detected variants was determined according to their prevalence and American College of Medical Genetics and Genomics recommendations. Baseline and follow-up clinical data were collected. The primary end point was a composite of death and heart transplantation. Overall, 42 pathogenic variants were identified in 38 patients (38%), with TTN , MYH 7, MYBPC 3, and DSP being the most commonly involved genes. At baseline, genotype-positive adults had higher rates of atrial fibrillation and family history, and lower left ventricular ejection fraction, compared with genotype-negative adults. During a median follow-up of 4.2 years, more primary end points occurred in genotype-positive adults than in genotype-negative adults (50.0% versus 23.5%; P=0.013). Multivariable analysis demonstrated that genotype-positive status was associated with higher risks of death and heart transplantation, independent of age, sex, and cardiac function at baseline in patients with LVNC (adjusted hazards ratio, 2.49; 95% confidence interval, 1.15-5.37; P=0.020). Conclusions Our study revealed a distinct genetic spectrum in Chinese patients with LVNC , with variants in TTN , MYH 7, MYBPC 3, and DSP being the most common. The presence of pathogenic variants is an independent risk factor for adverse outcomes and may aid in risk stratification in adult patients. Larger studies are needed to confirm these findings.

Phenotype and Functional Analyses in a Transgenic Mouse Model of Left Ventricular Noncompaction Caused by a DTNA Mutation.

DTNA encoding dystrobrevin-α (α-DB) is a putative causal gene associated with left ventricular noncompaction cardiomyopathy (LVNC). The aim of the study was to investigate the causal role of DTNA in LVNC using a transgenic mouse model.A missense mutation (c.146A > G, p.N49S) of DTNA was identified in a patient with LVNC by Sanger sequencing. Six independent lines of transgenic mice expressing the mutant DTNA under a myosin heavy chain 6 (Myh6) promoter were generated (Myh6:DtnaN49S). Phenotypic characteristics of DTNA-p.N49S mutations were evaluated by echocardiography, histological observation, and immunoblotting. Multiple trabeculation and a higher ratio of non-compacted to compact myocardial layer were found in the Myh6:DtnaN49S mice compared to the controls. The transgenic mice also showed left ventricular (LV) dilation and cardiac systolic dysfunction. In conclusion, overexpression of the DTNA-p.N49S mutation in a mouse heart can be responsible for the phenotype of deep trabeculation, dilated cardiomyopathy, and cardiac dysfunction, which resembles the phenotype of LVNC.

Investigation of novel metabolites potentially involved in the pathogenesis of coronary heart disease using a UHPLC-QTOF/MS-based metabolomics approach.

Coronary heart disease (CHD) is associated with complex metabolic disorders, but its molecular aetiology remains unclear. Using a novel nontargeted metabolomics approach, we explored the global metabolic perturbation profile for CHD. Blood samples from 150 patients with severe obstructive CHD and 150 angiographically normal controls were collected. Metabolic fingerprinting was performed by ultra-high performance liquid chromatography coupled to quadruple time-of-flight mass spectrometry (UHPLC-QTOF/MS) technique. After adjusting for CHD traditional risk factors and metabolic batch, a comprehensive list of 105 metabolites was found to be significantly altered in CHD patients. Among the metabolites identified, six metabolites were discovered to have the strongest correlation with CHD after adjusting for multiple testing: palmitic acid (ß = 0.205; p < 0.0001), linoleic acid (ß = 0.133; p < 0.0001), 4-pyridoxic acid (ß = 0.142; p < 0.0001), phosphatidylglycerol (20:3/2:0) (ß = 0.287; p < 0.0001), carnitine (14:1) (ß = 0.332; p < 0.0001) and lithocholic acid (ß = 0.224; p < 0.0001); of these, 4-pyridoxic acid, lithocholic acid and phosphatidylglycerol (20:3/2:0) were, to the best of our knowledge, first reported in this study. A logistic regression model further quantified their positive independent correlations with CHD. In conclusion, this study surveyed a broad panel of nontargeted metabolites in Chinese CHD populations and identified novel metabolites that are potentially involved in CHD pathogenesis.

Genetic Mechanisms Contribute to the Development of Heart Failure in Patients with Atrioventricular Block and Right Ventricular Apical Pacing.

Right ventricular apical (RVA) pacing can lead to progressive left ventricular dysfunction and heart failure (HF), even in patients with normal cardiac structure and function. Our study conducted candidate gene screening and lentivirus transfected neonatal rat cardiomyocytes (NRCMs) to explore the genetic and pathogenic mechanisms of RVA pacing induced cardiomyopathy in third degree atrioventricular block (III AVB) patients. We followed 887 III AVB patients with baseline normal cardiac function and RVA pacing. After a median follow-up of 2.5 years, 10 patients (four males, mean age 47.6 ± 10.0 years) were diagnosed with RVA pacing induced HF with left ventricular ejection fraction (LVEF) reducing dramatically to 37.8 ± 7.1% (P < 0.05). Candidate genes sequencing found cardiomyopathy associated genetic variations in all ten HF patients and six SCN5A variations in 6 of 20 control patients. Transfected NRCMs of Lamin A/C mutations (R216C and L379F) disrupted Lamin A/C location on nucleus membrane and finally resulted in increased apoptotic rate after serum starvation. In conclusion, cardiomyopathy associated genetic variations play an essential role in occurrence of newly onset HF in the III AVB patients with RVA pacing. RVA pacing, serving as extra stimulator, might accelerate the deterioration of cardiac structure and function.

De Novo FGF12 (Fibroblast Growth Factor 12) Functional Variation Is Potentially Associated With Idiopathic Ventricular Tachycardia.

BACKGROUND: Idiopathic ventricular tachycardia (VT) is a type of cardiac arrhythmia occurring in structurally normal hearts. The heritability of idiopathic VT remains to be clarified, and numerous genetic factors responsible for development of idiopathic VT are as yet unclear. Variations in FGF12 (fibroblast growth factor 12), which is expressed in the human ventricle and modulates the cardiac Na+ channel NaV1.5, may play an important role in the genetic pathogenesis of VT. METHODS AND RESULTS: We tested the hypothesis that genetic variations in FGF12 are associated with VT in 2 independent Chinese cohorts and resequenced all the exons and exon-intron boundaries and the 5' and 3' untranslated regions of FGF12 in 320 unrelated participants with idiopathic VT. For population-based case-control association studies, we chose 3 single-nucleotide polymorphisms-rs1460922, rs4687326, and rs2686464-which included all the exons of FGF12. The results showed that the single-nucleotide polymorphism rs1460922 in FGF12 was significantly associated with VT after adjusting for covariates of sex and age in 2 independent Chinese populations: adjusted P=0.015 (odds ratio: 1.54 [95% CI, 1.09-2.19]) in the discovery sample, adjusted P=0.018 (odds ratio: 1.64 [95% CI, 1.09-2.48]) in the replication sample, and adjusted P=2.52E-04 (odds ratio: 1.59 [95% CI, 1.24-2.03]) in the combined sample. After resequencing all amino acid coding regions and untranslated regions of FGF12, 5 rare variations were identified. The result of western blotting revealed that a de novo functional variation, p.P211Q (1.84% of 163 patients with right ventricular outflow tract VT), could downregulate FGF12 expression significantly. CONCLUSIONS: In this study, we observed that rs1460922 of FGF12 was significantly associated with VT and identified that a de novo variation of FGF12 may be an important genetic risk factor for the pathogenesis of VT.

Readthrough of SCN5A Nonsense Mutations p.R1623X and p.S1812X Questions Gene-therapy in Brugada Syndrome.

PURPOSE: Nonsense mutation readthrough is used as a gene-specific treatment in some genetic diseases. The response to readthrough treatment is determined by the readthrough efficiency of various nonsense mutations. In this manuscript, we aimed to explore the harmful effects of nonsense mutation suppression. METHODS: HEK293 cells were transfected with two SCN5A (encode cardiac Na+ channel) nonsense mutations, p.R1623X and p.S1812X. We applied two readthrough-enhancing methods (either aminoglycosides or a siRNA-targeting eukaryotic release factor eRF3a (a GTPase that binds eRF1)) to suppress these SCN5A nonsense mutations. When either of readthrough methods was used, the sodium channel proteins were examined by western blot and immunoblotting and recorded by whole cell patch-clamp to observe the functional characterization of the restored channels. RESULTS: Upon readthrough treatment, the sodium currents were restored to the mutant cDNAs. These mutations reduced full-length sodium channel protein levels, and the sodium currents were reduced to 3% of wild-type. The mutant cDNA sodium currents were increased to 30% of wild-type, and the fulllength proteins also increased. However, the functional characterization of these channels from cDNAs carrying p.R1623X and p.S1812X exhibited abnormal biophysical properties, including a negative shift in steady-state sodium channel inactivation, a positive shift in sodium channel activation and robust late sodium currents. The ramp test showed prolonged QT intervals. CONCLUSION: These results demonstrated that readthrough-enhancing methods effectively suppressed nonsense mutations in SCN5A and restored the expression of full-length channels. However, the restored channels may increase the risk of arrhythmia.

Molecular Mechanisms of Increased Heart Rate in Shenxianshengmai-treated Bradycardia Rabbits.

BACKGROUND: The molecular mechanisms of Shenxianshengmai (SXSM), a traditional Chinese medicine, on bradycardia have been incompletely understood. The study tried to investigate the gene expression profile and proteomics of bradycardia rabbits' hearts after SXSM treatment. METHODS: Twenty-four adult rabbits were randomly assigned in four groups: sham, model, model plus SXSM treatment, and sham plus SXSM treatment groups. Heart rate was recorded in all rabbits. Then, total RNA of atria and proteins of ventricle were isolated and quantified, respectively. Gene expression profiling was conducted by gene expression chip, and quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) was performed to confirm the results of gene expression chip. We used isobaric tags for elative and absolute quantitation and Western blotting to identify altered proteins after SXSM treatment. RESULTS: There was a constant decrease in the mean heart rate (32%, from 238 ± 6 beats/min to 149 ± 12 beats/min) after six weeks in model compared with that in sham group. This effect was partially reversed by 4-week SXSM treatment. Complementary DNA microarray demonstrated that the increased acetylcholinesterase and reduced nicotinic receptor were take responsibility for the increased heart rate. In addition, proteins involved in calcium handling and signaling were affected by SXSM treatment. Real-time RT-PCR verified the results from gene chip. Results from proteomics demonstrated that SXSM enhanced oxidative phosphorylation and tricarboxylic acid (TCA) cycle in ventricular myocardium to improve ATP generation. CONCLUSIONS: Long-term SXSM stimulates sympathetic transmission by increasing the expression of acetylcholinesterase and reduces the expression of nicotinic receptor to increase heart rate. SXSM also restored the calcium handling genes and altered genes involved in signaling. In addition, SXSM improves the ATP supply of ventricular myocardium by increasing proteins involved in TCA cycle and oxidation-respiratory chain.

The Effect of Wenxin Keli on the mRNA Expression Profile of Rabbits with Myocardial Infarction.

Aims. The molecular mechanisms of Chinese traditional medicine Wenxin Keli (WXKL) were unknown. This study was aimed at exploring the effects of WXKL on the gene expression profile and pathological alteration of rabbits with myocardial infarction. Methods. Twenty male adult rabbits were randomly divided into 4 groups: sham, model, WXKL, and captopril groups. Model, WXKL, and captopril groups underwent the ligation of the left anterior descending coronary artery while sham group went through an identical procedure without ligation. WXKL (817 mg/kg/d), captopril (8 mg/kg/d), and distilled water (to model and sham groups) were administered orally to each group. After 4 weeks, the rabbits were examined with echocardiography and the hearts were taken for expression chip and pathological staining (H&E, Masson, and Tunel) studies. Results. The data revealed that WXKL downregulated genes associated with inflammation (CX3CR1, MRC1, and FPR1), apoptosis (CTSC and TTC5), and neurohumoral system (ACE and EDN1) and upregulated angiogenesis promoting genes such as RSPO3. Moreover, the results also showed that WXKL improved cardiac function and prevented histopathological injury and apoptosis. Conclusion. The present study demonstrated that WXKL might play an important role in inhibiting inflammation, renin-angiotensin system, and apoptosis. It might be a promising Chinese medicine in the treatment of patients with myocardial infarction.

A novel mutation in the SCN5A gene contributes to arrhythmogenic characteristics of early repolarization syndrome.

Several genetic variants have been associated with early repolarization syndrome (ERS). However, the lack of functional validations of the mutant effects has limited the interpretation of genetic tests. In the present study, we identified and characterized a novel sodium channel, voltage gated, type V alpha subunit (SCN5A) mutation that was associated with ERS. A 67-year-old male proband suffering from recurrent syncope underwent a documented electrocardiogram (ECG) for polymorphic ventricular tachycardia (VT). It was noted that baseline 12-lead ECG exhibited a predominantly elevated ST-segment which mimicked acute myocardial ischemia in lead V2-V6, and the ECG also demonstrated J waves in lead Ⅱ, Ⅲ, aVF and V2-V6. Using genetic analysis, we noted that the proband carried a novel heterozygous missense mutation of A1055G in the SCN5A gene. Whole-cell configuration of patch-clamp analysis revealed that the mutation significantly decreased peak sodium current (INa) density and shifted the steady-state inactivation curve of INa to a more negative potential. Confocal imaging suggested that in the mutant channel a defect of protein expression both on the cell membrane and in cytoplasm was present. The present study demonstrated that a novel heterozygous missense mutation of A1055G in SCN5A led to 'loss-of function' of the sodium channels, and we suggest that it accounts for the arrhythmogenic characteristics of ERS.

Common Genotypes of Long QT Syndrome in China and the Role of ECG Prediction.

OBJECTIVES: Genetic testing, a gold standard for long QT syndrome (LQTS) diagnosis, is time-consuming and costly when all the 15 candidate genes are screened. Since genotype-specific ECG patterns are present in most LQT1-3 mutation carriers, we tested the utility of ECG-guided genotyping in a large cohort of Chinese LQTS patients. METHODS AND RESULTS: We enrolled 230 patients (26 ± 17 years, 66% female) with a clinical diagnosis of LQTS. Genotypes were predicted as LQT1-3 based on the presence of ECG patterns typical for each genotype in 200 patients (85 LQT1, 110 LQT2 and 5 LQT3). Family-based genotype prediction was also conducted if gene-specific ECG patterns were found in other affected family members. Mutational screening identified 104 mutations (44% novel), i.e. 46 KCNQ1, 54 KCNH2 and 4 SCN5A mutations. The overall predictive accuracy of ECG-guided genotyping was 79% (157/200) and 79% (67/85), 78% (86/110) and 80% (4/5) for LQT1, LQT2 and LQT3, respectively. The predictive accuracy was 98% (42/43) when family-based ECG assessment was performed. CONCLUSIONS: From this large-scale genotyping study, we found that LQT2 is the most common genotype among the Chinese. Family-based ECG-guided genotyping is highly accurate. ECG-guided genotyping is time- and cost-effective. We therefore recommend it as an optimal approach for the genetic diagnosis of LQTS.

A novel lamin A/C gene missense mutation (445 V > E) in immunoglobulin-like fold associated with left ventricular non-compaction.

AIMS: Two LMNA mutations (R644C and R190W) have been associated with familial and sporadic left ventricular non-compaction (LVNC). However, the mechanisms underlying these associations have not been elucidated. METHODS AND RESULTS: Genomic DNA was isolated from peripheral blood leucocytes and analysed by direct sequencing. Human embryonic kidney 293 cells were transfected with either wild type or mutant LMNA and SCN5A for whole-cell patch-clamp experiment and fluorescence microscopy. Point mutation modeling for mutant LMNA was also performed. One novel LVNC-associated mutation (V445E) in ß2 sheet of immunoglobulin (Ig)-like fold was found in the proband and his father. We also found that the peak current of sodium channel was markedly reduced in mutant LMNA compared with WT while the activation, inactivation, and recovery curves were not significantly altered. The mutant lamin A/C were aggregated into multiple highlighted particles. Three ß sheets and multiple side chains in Ig-like fold were altered due to the replacement of a valine by glutamic acid. CONCLUSION: Our data associated a novel lamin A/C mutation (V445E) with a sudden death form of familial LVNC. The reduced sodium current in mutant LMNA may account for the advent of malignant ventricular arrhythmias. The altered structures of three ß sheets and side chains may partially explain the aggregation of lamin A/C protein subjacent to the nuclear envelope.