Rare Variant Genetics and Dilated Cardiomyopathy Severity: The DCM Precision Medicine Study.

BACKGROUND: Dilated cardiomyopathy (DCM) can lead to advanced disease, defined herein as necessitating a durable left ventricular assist device or a heart transplant (LVAD/HT). DCM is known to have a genetic basis, but the association of rare variant genetics with advanced DCM has not been studied. METHODS: We analyzed clinical and genetic sequence data from patients enrolled between 2016 and 2021 in the US multisite DCM Precision Medicine Study, which was a geographically diverse, multiracial, multiethnic cohort. Clinical evaluation included standardized patient interview and medical record query forms. DCM severity was classified into 3 groups: patients with advanced disease with LVAD/HT; patients with an implantable cardioverter defibrillator (ICD) only; or patients with no ICD or LVAD/HT. Rare variants in 36 DCM genes were classified as pathogenic or likely pathogenic or variants of uncertain significance. Confounding factors we considered included demographic characteristics, lifestyle factors, access to care, DCM duration, and comorbidities. Crude and adjusted associations between DCM severity and rare variant genetic findings were assessed using multinomial models with generalized logit link. RESULTS: Patients' mean (SD) age was 51.9 (13.6) years; 42% were of African ancestry, 56% were of European ancestry, and 44% were female. Of 1198 patients, 347 had LVAD/HT, 511 had an ICD, and 340 had no LVAD/HT or ICD. The percentage of patients with pathogenic or likely pathogenic variants was 26.2%, 15.9%, and 15.0% for those with LVAD/HT, ICD only, or neither, respectively. After controlling for sociodemographic characteristics and comorbidities, patients with DCM with LVAD/HT were more likely than those without LVAD/HT or ICD to have DCM-related pathogenic or likely pathogenic rare variants (odds ratio, 2.3 [95% CI, 1.5-3.6]). The association did not differ by ancestry. Rare variant genetic findings were similar between patients with DCM with an ICD and those without LVAD/HT or ICD. CONCLUSIONS: Advanced DCM was associated with higher odds of rare variants in DCM genes adjudicated as pathogenic or likely pathogenic, compared with individuals with less severe DCM. This finding may help assess the risk of outcomes in management of patients with DCM and their at-risk family members. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03037632.

Genetic Architecture of Dilated Cardiomyopathy in Individuals of African and European Ancestry.

Importance: Black patients with dilated cardiomyopathy (DCM) have increased familial risk and worse outcomes than White patients, but most DCM genetic data are from White patients. Objective: To compare the rare variant genetic architecture of DCM by genomic ancestry within a diverse population of patients with DCM. Design: Cross-sectional study enrolling patients with DCM who self-identified as non-Hispanic Black, Hispanic, or non-Hispanic White from June 7, 2016, to March 15, 2020, at 25 US advanced heart failure programs. Variants in 36 DCM genes were adjudicated as pathogenic, likely pathogenic, or of uncertain significance. Exposure: Presence of DCM. Main Outcomes and Measures: Variants in DCM genes classified as pathogenic/likely pathogenic/uncertain significance and clinically actionable (pathogenic/likely pathogenic). Results: A total of 505, 667, and 26 patients with DCM of predominantly African, European, or Native American genomic ancestry, respectively, were included. Compared with patients of European ancestry, a lower percentage of patients of African ancestry had clinically actionable variants (8.2% [95% CI, 5.2%-11.1%] vs 25.5% [95% CI, 21.3%-29.6%]), reflecting the lower odds of a clinically actionable variant for those with any pathogenic variant/likely pathogenic variant/variant of uncertain significance (odds ratio, 0.25 [95% CI, 0.17-0.37]). On average, patients of African ancestry had fewer clinically actionable variants in TTN (difference, -0.09 [95% CI, -0.14 to -0.05]) and other genes with predicted loss of function as a disease-causing mechanism (difference, -0.06 [95% CI, -0.11 to -0.02]). However, the number of pathogenic variants/likely pathogenic variants/variants of uncertain significance was more comparable between ancestry groups (difference, -0.07 [95% CI, -0.22 to 0.09]) due to a larger number of non-TTN non-predicted loss of function variants of uncertain significance, mostly missense, in patients of African ancestry (difference, 0.15 [95% CI, 0.00-0.30]). Published clinical case-based evidence supporting pathogenicity was less available for variants found only in patients of African ancestry (P < .001). Conclusion and Relevance: Patients of African ancestry with DCM were less likely to have clinically actionable variants in DCM genes than those of European ancestry due to differences in genetic architecture and a lack of representation of African ancestry in clinical data sets.

Prevalence and Cumulative Risk of Familial Idiopathic Dilated Cardiomyopathy.

Importance: Idiopathic dilated cardiomyopathy (DCM) aggregates in families, and early detection in at-risk family members can provide opportunity to initiate treatment prior to late-phase disease. Most studies have included only White patients, yet Black patients with DCM have higher risk of heart failure-related hospitalization and death. Objective: To estimate the prevalence of familial DCM among DCM probands and the age-specific cumulative risk of DCM in first-degree relatives across race and ethnicity groups. Design, Setting, and Participants: A family-based, cross-sectional study conducted by a multisite consortium of 25 US heart failure programs. Participants included patients with DCM (probands), defined as left ventricular systolic dysfunction and left ventricular enlargement after excluding usual clinical causes, and their first-degree relatives. Enrollment commenced June 7, 2016; proband and family member enrollment concluded March 15, 2020, and April 1, 2021, respectively. Exposures: The presence of DCM in a proband. Main Outcomes and Measures: Familial DCM defined by DCM in at least 1 first-degree relative; expanded familial DCM defined by the presence of DCM or either left ventricular enlargement or left ventricular systolic dysfunction without known cause in at least 1 first-degree relative. Results: The study enrolled 1220 probands (median age, 52.8 years [IQR, 42.4-61.8]; 43.8% female; 43.1% Black and 8.3% Hispanic) and screened 1693 first-degree relatives for DCM. A median of 28% (IQR, 0%-60%) of living first-degree relatives were screened per family. The crude prevalence of familial DCM among probands was 11.6% overall. The model-based estimate of the prevalence of familial DCM among probands at a typical US advanced heart failure program if all living first-degree relatives were screened was 29.7% (95% CI, 23.5% to 36.0%) overall. The estimated prevalence of familial DCM was higher in Black probands than in White probands (difference, 11.3% [95% CI, 1.9% to 20.8%]) but did not differ significantly between Hispanic probands and non-Hispanic probands (difference, -1.4% [95% CI, -15.9% to 13.1%]). The estimated prevalence of expanded familial DCM was 56.9% (95% CI, 50.8% to 63.0%) overall. Based on age-specific disease status at enrollment, estimated cumulative risks in first-degree relatives at a typical US advanced heart failure program reached 19% (95% CI, 13% to 24%) by age 80 years for DCM and 33% (95% CI, 27% to 40%) for expanded DCM inclusive of partial phenotypes. The DCM hazard was higher in first-degree relatives of non-Hispanic Black probands than non-Hispanic White probands (hazard ratio, 1.89 [95% CI, 1.26 to 2.83]). Conclusions and Relevance: In a US cross-sectional study, there was substantial estimated prevalence of familial DCM among probands and modeled cumulative risk of DCM among their first-degree relatives. Trial Registration: ClinicalTrials.gov Identifier: NCT03037632.

Impact of Racial and Ethnic Disparities on Patients With Dilated Cardiomyopathy: JACC Focus Seminar 7/9.

Significant race- and ethnicity-based disparities among those diagnosed with dilated cardiomyopathy (DCM) exist and are deeply rooted in the history of many societies. The role of social determinants of racial disparities, including racism and bias, is often overlooked in cardiology. DCM incidence is higher in Black subjects; survival and other outcome measures are worse in Black patients with DCM, with fewer referrals for transplantation. DCM in Black patients is underrecognized and under-referred for effective therapies, a consequence of a complex interplay of social and socioeconomic factors. Strategies to manage social determinants of health must be multifaceted and consider changes in policy to expand access to equitable care; provision of insurance, education, and housing; and addressing racism and bias in health care workers. There is an urgent need to prioritize a social justice approach to health care and the pursuit of health equity to eliminate race and other disparities in the management of cardiovascular disease.

Effect of rs4646994 polymorphism of angiotensin-converting enzyme on the risk of nonischemic cardiomyopathy.

BACKGROUND: Angiotensin-converting enzyme (ACE) gene polymorphisms have recently been shown to be associated with risk of developing left ventricular hypertrophy (LVH). However, the results were controversial. We aimed to conduct this meta-analysis to further confirm the association between ACE rs4646994 polymorphism and hypertrophic cardiomyopathy (HCM)/dilated cardiomyopathy (DCM). METHODS: PubMed, Embase, the Chinese National Knowledge Information, and Wanfang databases were searched for eligible studies. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of included studies. Then we evaluated the association between ACE gene mutation and HCM/DCM by calculating odds ratios (ORs) and 95% confidence intervals (95% CIs). Subgroup analysis was further performed to explore situations in specialized subjects. Sensitivity analysis and publication bias was assessed to confirm the study reliability. RESULTS: There were 13 studies on DCM (2004 cases and 1376 controls) and 16 studies on HCM (2161 controls and 1192 patients). ACE rs4646994 polymorphism was significantly associated with DCM in all genetic models. However, in HCM, four genetic models (allele model, homozygous model, heterozygous model, and dominant model) showed significant association between ACE rs4646994 polymorphism and DCM. In subgroup analysis, we found that ACE rs4646994 polymorphism was significantly associated with DCM/HCM in Asian population. Finally, we also conducted a cumulative meta-analysis, which indicates that the results of our meta-analysis are highly reliable. CONCLUSION: ACE rs4646994 polymorphism increases the risk of DCM/HCM in Asians, but not in Caucasians. More case-control studies are needed to strengthen our conclusions and to assess the gene-gene and gene-environment interactions between ACE rs4646994 polymorphism and DCM/HCM.

Family screening in black patients with isolated left ventricular non-compaction: the Chris Hani Baragwanath experience.

BACKGROUND: Isolated left ventricular non-compaction (ILVNC), dilated cardiomyopathy (DCMO) and hypertrophic cardiomyopathy (HCM) are diseases that may be present in family members of patients with ILVNC. The primary aim of this study was to identify the prevalence and spectrum of cardiomyopathy in first-degree relatives of patients with ILVNC. A secondary aim was to compare a strategy of clinical screening, utilising only a clinical assessment and electrocardiogram (ECG), compared to one that included echocardiography for screening of family members of patients with ILVNC. METHODS: Eighty-three close relatives of 38 unrelated patients from the ILVNC clinic at the Chris Hani Baragwanath Hospital underwent a detailed clinical history, physical examination, ECG and echocardiogram. RESULTS: Echocardiographic screening revealed unexplained left ventricular (LV) dysfunction in 10 (12.05%) relatives. Nine out of the 10 individuals satisfied the criteria for diagnosis of DCMO. No cases of HCM or LVNC were identified. A strategy of clinical assessment and ECG had a sensitivity of 76% and a specificity of 42% versus the gold standard of echocardiographic screening. CONCLUSIONS: Echocardiographic screening detected DCMO in 10.8% of subjects. A strategy of clinical screening that included electrocardiography was sub-optimal as a screening strategy compared to echocardiographic screening.

Impact of LDB3 gene polymorphisms on clinical presentation and implantable cardioverter defibrillator (ICD) implantation in Chinese patients with idiopathic dilated cardiomyopathy.

OBJECTIVE: Mutations in LIM domain binding 3 (LDB3) gene cause idiopathic dilated cardiomyopathy (IDCM), a structural heart disease with a complicated genetic background. However, the association of polymorphisms in the LDB3 gene with susceptibility to IDCM in Chinese populations remains unexplored as dose the impact on clinical presentation. METHODS: We sequenced all exons and the adjacent part of introns of the LDB3 gene in 159 Chinese Han IDCM patients and 247 healthy controls. Then we detected the distribution of polymorphisms in the LDB3 gene in all participants and assessed their associations with risk of IDCM. Additionally, we conducted a stratified genotype-phenotype correlation analysis. RESULTS: The A allele of rs4468255 was significantly associated with IDCM (P<0.01). The rs4468255, rs11812601, rs56165849, and rs3740346 were also associated with diastolic blood pressure (DBP) and left ventricular ejection fraction (LVEF) (P<0.05). Notably, a higher frequency of rs4468255 polymorphism was observed in implantable cardioverter defibrillator (ICD) recipients under a recessive model (P<0.01), whereas the significant association disappeared after adjusting for potential confounders. However, in the dominant model, notable correlations could only be observed after adjusting for multi parameters. CONCLUSIONS: The rs4468255 was significantly correlated with IDCM of Chinese Han population. A allele of rs4468255 is higher in IDCM patients with ICD implantation, suggesting the influence of genetic background in the generation of this response. In addition, rs11812601, rs56165849, and rs3740346 in LDB3 show association with brain natriuretic peptide, DBP, and LVEF levels in patients with IDCM but did not show any association with IDCM susceptibility.

Tumor Necrosis Factor-α Gene Polymorphism (G-308A) and Dilated Cardiomyopathy.

The issue that genetic polymorphism of tumor necrosis factor-α (TNF-α) is associated with dilated cardiomyopathy (DCM) is debatable. We sought to investigate the potential role of TNF-α gene polymorphism (G-308A) in the susceptibility to dilated cardiomyopathy.We retrieved PubMed, EMBASE, and CNKI to collect all articles which reported on the association between TNF-α G-308A polymorphism and dilated cardiomyopathy. Two authors used the Newcastle-Ottawa Scale (NOS) checklist to assess the quality of the included studies. The odds ratio (OR) with 95% confidence intervals (CI) were pooled in a specific genetic model to assess the association and Stata version 14.0 software was used.A total of 9 studies with 1338 patients and 1677 controls were included in this study. The results from this meta-analysis indicated that TNF-α G-308A polymorphism significantly increased the risk of dilated cardiomyopathy in heterozygous comparison (GA versus GG: OR = 1.87; 95%CI = 1.03-3.40; P < 0.05). The increased risk of DCM was also found in Asian populations using a dominant model and heterozygous comparison (GA+AA versus GG: OR = 2.00, 95%CI = 1.02-3.92, P < 0.05; GA versus GG: OR = 1.94, 95%CI = 1.23-3.06, P < 0.05).The current meta-analysis revealed that TNF-α gene polymorphism (G-308A) may be associated with the susceptibility to DCM.

Association of Variants in BAG3 With Cardiomyopathy Outcomes in African American Individuals.

Importance: The prevalence of nonischemic dilated cardiomyopathy (DCM) is greater in individuals of African ancestry than in individuals of European ancestry. However, little is known about whether the difference in prevalence or outcomes is associated with functional genetic variants. Objective: We hypothesized that Bcl2-associated anthanogene 3 (BAG3) genetic variants were associated with outcomes in individuals of African ancestry with DCM. Design: This multicohort study of the BAG3 genotype in patients of African ancestry with dilated cardiomyopathy uses DNA obtained from African American individuals enrolled in 3 clinical studies: the Genetic Risk Assessment of African Americans With Heart Failure (GRAHF) study; the Intervention in Myocarditis and Acute Cardiomyopathy Trial-2 (IMAC-2) study; and the Genetic Risk Assessment of Cardiac Events (GRACE) study. Samples of DNA were also acquired from the left ventricular myocardium of patients of African ancestry who underwent heart transplant at the University of Colorado and University of Pittsburgh. Main Outcomes and Measures: The primary end points were the prevalence of BAG3 mutations in African American individuals and event-free survival in participants harboring functional BAG3 mutations. Results: Four BAG3 genetic variants were identified; these were expressed in 42 of 402 African American individuals (10.4%) with nonischemic heart failure and 9 of 107 African American individuals (8.4%) with ischemic heart failure but were not present in a reference population of European ancestry (P < .001). The variants included 2 nonsynonymous single-nucleotide variants; 1 three-nucleotide in-frame insertion; and 2 single-nucleotide variants that were linked in cis. The presence of BAG3 variants was associated with a nearly 2-fold (hazard ratio, 1.97 [95% CI, 1.19-3.24]; P = .01) increase in cardiac events in carriers compared with noncarriers. Transfection of transformed adult human ventricular myocytes with plasmids expressing the 4 variants demonstrated that each variant caused an increase in apoptosis and a decrease in autophagy when samples were subjected to the stress of hypoxia-reoxygenation. Conclusions and Relevance: This study demonstrates that genetic variants in BAG3 found almost exclusively in individuals of African ancestry were not causative of disease but were associated with a negative outcome in patients with a dilated cardiomyopathy through modulation of the function of BAG3. The results emphasize the importance of biological differences in causing phenotypic variance across diverse patient populations, the need to include diverse populations in genetic cohorts, and the importance of determining the pathogenicity of genetic variants.

Rare genetic mutations in Pakistani patients with dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a leading cause of heart failure, and heart transplantation globally. There is enlargement of left ventricle of the heart impairing the systolic function in this disorder. The involvement of genetic factors in the pathogenesis of DCM has been reported in up to 50% of the cases. However, due to the complexity and heterogeneity of the disease, the complete pathophysiology remains unclear. In this study, whole exomes of five unrelated patients of idiopathic DCM were sequenced to an average depth of 100× using Illumina HiSeq4000 system. The analysis of the data with in silico tools SIFT, Polyphen2, and CADD showed 494 rare (AF < 1.0%) missense SNVs predicted as deleterious. Detrimental variants in genes highly expressed in cardiac tissue included 3 rare allele frequency loss-of-function SNVs in C2orf40, MYOM3, and TMED4 genes, a homozygous frameshift insertion in RTKN2, and a splice site homozygous deletion in SLC6A6 in at least one of the patients. The stop-gained SNV rs143187236 of MYOM3 (myomesin 3) was found in perfect linkage disequilibrium (r2 = 1.0) with its neighboring missense SNV rs149105212 in two of the patients, representing the role of myomesin 3 in pathophysiology of DCM. Allele frequency comparison showed three variants rs375563861 (C2orf40), rs143187236 (MYOM3), and rs564181443 (RTKN2) having 3 fold or higher allele frequency in South Asians than in the global populations. The identified pathogenic variants can be used in risk assessment and precision therapy in DCM patients.

Whole exome sequencing identifies a novel mutation (c.333 + 2T > C) of TNNI3K in a Chinese family with dilated cardiomyopathy and cardiac conduction disease.

Dilated Cardiomyopathy (DCM) and cardiac conduction disease (CCD) are two kinds if diseases that can induce heart failure, syncope and even sudden cardiac death (SCD). DCM patients can experience CCD at the same time. In recent research, some disease-causing genes and variants have been identified in patients with DCM and CCD, such as Alpha-Actinin-2 and TNNI3 Interacting Kinase (TNNI3K). In this study, we employed whole-exome sequencing (WES) to explore the potential causative genes in a Chinese family with DCM and CCD. A novel splice site mutation (c.333 + 2 T > C) of TNNI3K was identified and co-segregated with the affected family members. This novel mutation was also absent in 200 healthy local controls and predicted to be disease-causing by Mutationtaster. The splice site mutation (c.333 + 2 T > C) may result in a premature stop codon in exon 4 of the TNNI3K gene and can induce nonsense-mediated mRNA decay. Real-time qPCR also confirmed that the level of TNNI3K mRNA expression was decreased significantly compared with the controls, which may lead to myocardial structural disorder and arrhythmia. In this study we reported the third novel mutation of TNNI3K in DCM and CCD patients which further supported the important role of TNNI3K in heart development and expanded the spectrum of TNNI3K mutations. The results may contribute to the genetic diagnosis and counseling of families with DCM and CCD.

Influence of LGALS3 gene polymorphisms on susceptibility and prognosis of dilated cardiomyopathy in a Northern Han Chinese population.

BACKGROUND: Galectin-3 plays an important role in modulating cardiac inflammation and fibrosis. It also takes part in the pathways underlying cardiac remodeling. Therefore, LGALS3 gene, encoding galectin-3 protein, is a promising candidate for the genetic study of dilated cardiomyopathy (DCM). To date, there has been no research evaluating the association between LGALS3 gene polymorphisms and the susceptibility and prognosis of DCM. METHODS AND RESULTS: Genotyping of 4 single nucleotide polymorphisms (SNPs) in the LGALS3 gene, which were reported to be functional in the literature, was performed in 279 unrelated clinically diagnosed DCM patients and 363 apparently healthy controls from Northern Han Chinese population using iPLEX SNP Genotyping analysis on a Sequenom MassARRAY System. The frequency of G allelic polymorphism of rs1009977 and the C allelic polymorphism of rs4652 were lower in DCM patients (OR=0.77, 95% CI [0.60-0.99], P=0.045; OR=0.79, 95% CI [0.63-0.99], P=0.042, respectively). The minor variants of rs1009977 and rs4652 were associated with low susceptibility of DCM under additive genetic models (P=0.045 and P=0.040, respectively). The AA genotype of both rs2274273 and rs4644 was associated with lower left ventricular ejection fraction (recessive model, P=0.018 for both; additive model, P=0.039 for both). The G variant of rs1009977 was related with lower serum galectin-3 level in DCM patients under three genetic models (additive model, P=0.020, dominant model, P=0.020, recessive model, P=0.037). The A variant of both rs2274273 and rs4644 was associated with lower level of galectin-3 in DCM patients under additive model (P=0.032 for both) and dominant model (P=0.012 for both). None of the 4 SNPs was associated with the cardiovascular or all-cause death rate of DCM. In Conclusion, LGALS3 gene polymorphisms might be associated with the susceptibility of DCM in a Northern Han Chinese population.

Toward Genetics-Driven Early Intervention in Dilated Cardiomyopathy: Design and Implementation of the DCM Precision Medicine Study.

BACKGROUND: The cause of idiopathic dilated cardiomyopathy (DCM) is unknown by definition, but its familial subtype is considered to have a genetic component. We hypothesize that most idiopathic DCM, whether familial or nonfamilial, has a genetic basis, in which case a genetics-driven approach to identifying at-risk family members for clinical screening and early intervention could reduce morbidity and mortality. METHODS: On the basis of this hypothesis, we have launched the National Heart, Lung, and Blood Institute- and National Human Genome Research Institute-funded DCM Precision Medicine Study, which aims to enroll 1300 individuals (600 non-Hispanic African ancestry, 600 non-Hispanic European ancestry, and 100 Hispanic) who meet rigorous clinical criteria for idiopathic DCM along with 2600 of their relatives. Enrolled relatives will undergo clinical cardiovascular screening to identify asymptomatic disease, and all individuals with idiopathic DCM will undergo exome sequencing to identify relevant variants in genes previously implicated in DCM. Results will be returned by genetic counselors 12 to 14 months after enrollment. The data obtained will be used to describe the prevalence of familial DCM among idiopathic DCM cases and the genetic architecture of idiopathic DCM in multiple ethnicity-ancestry groups. We will also conduct a randomized controlled trial to test the effectiveness of Family Heart Talk, an intervention to aid family communication, for improving uptake of preventive screening and surveillance in at-risk first-degree relatives. CONCLUSIONS: We anticipate that this study will demonstrate that idiopathic DCM has a genetic basis and guide best practices for a genetics-driven approach to early intervention in at-risk relatives. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03037632.

Characteristics and In-Hospital Outcomes of Peripartum Cardiomyopathy Diagnosed During Delivery in the United States From the Nationwide Inpatient Sample (NIS) Database.

BACKGROUND: Peripartum cardiomyopathy (PPCM) is associated with advanced maternal age, African-American race, hypertensive disorders of pregnancy, and multiple-gestation pregnancies. Less is known regarding racial differences in risk factors and predictors of adverse in-hospital outcomes. METHODS AND RESULTS: A total of 1,337 women with PPCM were identified with the use of the Nationwide Inpatient Sample (2004-2011). Clinical profiles and maternal outcomes in delivering mothers with and without PPCM were compared and stratified by race. In multivariate analysis, established risk factors for PPCM were confirmed. Anemia (odds ratio [OR] 2.0, 95% confidence interval [CI] 1.6-2.5; P < .0001), asthma (OR 2.2, 95% CI 1.5-3.2; P = .0002), smoking (OR 33.6, 95% CI 9.3-159.4; P < .0001), and thyroid disease (OR 5.9; 95% CI 1.5-21.3; P = .01) were associated with PPCM. Risk factors significant in whites, African Americans, and Hispanics were hypertension during pregnancy and anemia. Patients with PPCM had higher rates of in-hospital adverse outcomes (P < .0001), but no differences in race or comorbidities predicted adverse events. CONCLUSIONS: Hypertensive disorders during pregnancy and anemia were associated with PPCM in whites, African Americans, and Hispanics, providing further evidence that vascular stress may play a role in the pathogenesis of PPCM. Thyroid disorders may represent a novel risk factor for PPCM.

TNNT2 Gene Polymorphisms are Associated with Susceptibility to Idiopathic Dilated Cardiomyopathy in Kazak and Han Chinese.

BACKGROUND: Dilated cardiomyopathy (DCM) is characterized by left ventricular enlargement, systolic dysfunction, and heart failure. Both genetic and non-genetic factors have been linked to DCM pathogenesis. Familial DCM (FDCM) accounts for 20%-50% of all DCM cases, highlighting the importance of genetics in pathogenesis. Indeed, more than 40 DCM-associated genes have been identified, including the gene encoding cardiac troponin T type-2 (TNNT2). We examined polymorphisms of the TNNT2 gene in idiopathic DCM (IDCM) patients of Kazak and Han ethnicity compared with healthy Kazak and Han controls. MATERIAL AND METHODS: Peripheral blood samples were collected from 180 patients with IDCM (90 Kazak and 90 Han), and 180 healthy controls (90 Kazak and 90 Han). PCR was used to amplify 15 exons and nearby introns of the TNNT2 gene. The amplified products were sequenced and compared to the standard sequence in PubMed by BLAST and CHROMAS software, to identify mutation sites. RESULTS: Results from Kazak and Han IDCM patients were complied for Hardy-Weinberg equilibrium analysis. There was a significant difference in the genotype distribution (χ2=6.67, P=0.015) and allele frequency (χ2=5.71, P=0.017) between Kazaks with IDCM and Kazak controls of SNP rs3729547. There was also a difference in the genotype distribution (χ2=6.62, P=0.036) and allele frequency (χ2=4.91, P=0.018) between Han with IDCM and Han controls. The TNNT2 gene polymorphism loci rs3729547 may be associated with the IDCM onset in Kazak and Han patients (OR=2.5, 95% CI: 1.233~5.068). CONCLUSIONS: The TNNT2 polymorphisms might play an important role in susceptibility to DCM in Xinjiang Kazak and Han patients.

Nonsense mutations in BAG3 are associated with early-onset dilated cardiomyopathy in French Canadians.

BACKGROUND: Dilated cardiomyopathy (DCM) is a major cause of heart failure that may require heart transplantation. Approximately one third of DCM cases are familial. Next-generation DNA sequencing of large panels of candidate genes (ie, targeted sequencing) or of the whole exome can rapidly and economically identify pathogenic mutations in familial DCM. METHODS: We recruited 64 individuals from 26 DCM families followed at the Montreal Heart Institute Cardiovascular Genetic Center and sequenced the whole exome of 44 patients and 2 controls. Both affected and unaffected family members underwent genotyping for segregation analysis. RESULTS: We found 2 truncating mutations in BAG3 in 4 DCM families (15%) and confirmed segregation with disease status by linkage (log of the odds [LOD] score = 3.8). BAG3 nonsense mutations conferred a worse prognosis as evidenced by a younger age of clinical onset (37 vs 48 years for carriers and noncarriers respectively; P = 0.037). We also found truncating mutations in TTN in 5 families (19%). Finally, we identified potential pathogenic mutations for 9 DCM families in 6 candidate genes (DSP, LMNA, MYH7, MYPN, RBM20, and TNNT2). We still need to confirm several of these mutations by segregation analysis. CONCLUSIONS: Screening an extended panel of 41 candidate genes allowed us to identify probable pathogenic mutations in 69% of families with DCM in our cohort of mostly French-Canadian patients. We confirmed the prevalence of TTN nonsense mutations in DCM. Furthermore, to our knowledge, we are the first to present an association between nonsense mutations in BAG3 and early-onset DCM.

Cardiac troponin T (TNNT2) mutations in chinese dilated cardiomyopathy patients.

BACKGROUND: Dilated cardiomyopathy (DCM) is one of the leading causes of heart failure with high morbidity and mortality. Although more than 40 genes have been reported to cause DCM, the role of genetic testing in clinical practice is not well defined. Mutations in the troponin T (TNNT2) gene represent an important subset of known disease-causing mutations associated with DCM. Therefore, the aim of the present study was to determine the genetic variations in TNNT2 and the associations of those variations with DCM in Chinese patients. METHODS: An approximately 4 kb fragment of the TNNT2 gene was isolated from 103 DCM patients and 192 healthy controls and was analyzed by DNA sequence analysis for genetic variations. RESULTS: A total of 6 TNNT2 mutations were identified in 99 patients, including a G321T missense mutation (Leu84Phe) and 5 novel intronic mutations. Alleles of two novel SNPs (c.192 + 353 C>A, OR = 0.095, 95% CI: 0.013-0.714, P = 0.022; c.192 + 463 G>A, OR = 0.090, 95% CI: 0.012-0.675, P = 0.019) and SNP rs3729843 (OR = 1.889, 95% CI: 1.252-2.852; P = 0.002) were significantly correlated with DCM. CONCLUSIONS: These results suggest that the missense mutation (Leu84Phe) and two novel SNPs (c.192 + 353 C>A, c.192 + 463 G>A) in TNNT2 gene might be associated with DCM in the Chinese population.

[Association of programmed cell death 1 gene polymorphisms with dilated cardiomyopathy in Chinese Han population].

OBJECTIVE: To investigate the association between programmed death 1 (PDCD1) gene polymorphism and dilated cardiomyopathy (DCM). METHODS: Two single nucleotide polymorphisms (SNPs) of the PDCD1 gene, rs2227981, rs2227982, were genotyped and detected in 340 DCM patients and 401 healthy controls using the method of polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP). The genotype frequencies and allele frequencies of SNPs were compared between DCM patients and normal controls. RESULTS: The genotype and allele distributions of rs2227982 were significantly different between the patients with DCM and the controls. The frequencies of TT genotype and T allele of rs2227982 were higher in the patients than those in the controls (35.3% vs. 23.4%, P < 0.01, OR=2.37, 95%CI: 1.57-3.57; 58.5% vs. 47.4%, P < 0.01, OR=1.58, 95%CI: 1.28-1.93, respectively). No association was observed for rs2227981 between the DCM patients and the controls. CONCLUSION: rs2227982 in PDCD1 gene is association with DCM in Chinese Han population, which supported PDCD1 as a susceptibility gene for DCM. TT genotypes and T allele in rs2227982 may be associated with significantly increased risk of DCM.

[Association between LMNA mutation and familial and idiopathic dilated cardiomyopathy patients in Xinjiang].

OBJECTIVE: To explore the association between LMNA gene mutation and familiar dilated cardiomyopathy (DCM) (FDCM) and idiopathic DCM (IDCM) in Uygurs and Hans people in Xinjiang area. METHODS: Peripheral blood samples were collected from 28 family member with FDCM and 123 sporadic patients with IDCM(56 Uygur patients and 67 Han patients), 80 Uygur and 80 Han people were chosen as normal controls. PCR was used to amplify the 12 exons of LMNA gene. The amplified products were sequenced and compared with the standard sequence in the NCBI to determine the mutation sites. RESULTS: Transmission of the allele C and T of rs4641 was similar in Han FDCM patients. One new variation(c.1714C>T) located at exon 10 of LMNA gene was identified in 1 Han patient with IDCM, this mutation caused an amino acid substitution (R572C). In Uygurs people, rs553016 polymorphism was significant different between IDCM and control groups (P < 0.05). Logistic regression revealed that rs553016 was an independent risk factor for Uygurs patients with IDCM (OR = 3.178, P = 0.035). CONCLUSIONS: LMNA rs4641 is not associated with FDCM of Hans people in Xinjiang while LMNA mutation is associated with IDCM and rs533106 polymorphism is an independent risk factor for Uygurs patients with IDCM.