Search

Background: Genetics of sudden cardiac deaths (SCD) remains frequently undetected. Genetic analysis is recommended in undefined selected cases in the 2021 ERC-guideline. The emergency medical service and physicians (EMS) may play a pivotal role for unraveling SCD by saving biomaterial for later molecular autopsy. Since for high-throughput DNA-sequencing (NGS) high quality genomic DNA is needed. We investigated in a prospective proof-of-concept study the role of the EMS for the identification of genetic forms of SCDs in the young.Methods: We included patients aged 1-50 years with need for cardiopulmonary resuscitation attempts (CPR). Cases with non-natural deaths were excluded. In two German counties with 562,904 residents 39,506 services were analysed. Paired end panel-sequencing was performed, and variants were classified according to guidelines of the American College of Medical Genetics (ACMG).Results: 769 CPR-attempts were recorded (1.95% of all EMS-services; CPR-incidence 68/100,000). In 103 cases CPR were performed in patients < 50y. 58% died on scene, 26% were discharged from hospital. 24 subjects were included for genotyping. Of these 33% died on scene, 37.5% were discharged from hospital. 25% of the genotyped patients were carriers of (likely) pathogenic (ACMG-4/-5) variants. 67% carried variants with unknown significance (ACMG-3). 2 of them had familial history for arrhythmogenic cardiomyopathy or had to be re-classified as ACMG-4 carriers due to whole exome sequencing.Conclusion: The EMS contributes especially in fatal OHCA-cases to increase the yield of identified genetic conditions by collecting a blood sample on scene. Thus, the EMS can contribute significantly to primary and secondary prophylaxis in affected families. [ABSTRACT FROM AUTHOR]

Internal tandem duplications (ITDs) of the juxtamembrane region of the FLT3 tyrosine kinase receptor are the most frequent genetic alterations in acute myeloid leukemia (AML). The presence of this mutation has been recognized as an independent poor prognostic factor. In this study, we compared the FLT3 mutational status between diagnosis and subsequent relapses in 31 patients with AML. At diagnosis, seven patients were identified to contain FLT3-ITD mutations and one patient to harbor the D835 mutation. Five patients remained FLT3-ITD positive throughout the disease course (+/+). Three patients lost the FLT3 gene mutation at first (one FLT3-ITD, one D835 mutation), or second relapse (one FLT3-ITD) (+/-). One additional patient lost a small FLT3-ITD positive clone at relapse and at the same time gained an apparently unrelated FLT3-ITD positive clone. One patient without FLT3 mutation at diagnosis relapsed with an FLT3-ITD mutation (-/+). A shorter median duration of first remission (6 months versus 11.5 months) and a higher relapse rate after salvage therapy (e.g. allogeneic peripheral blood stem cell transplantation) resulted in a lower leukemia-free survival in the FLT3 mutated group (11% versus 31%). The loss of a clone with a mutation in the FLT3 gene at relapse did not improve the prognosis. [Copyright &y& Elsevier]

Transcription factor CCAAT/enhancer binding protein α (C/EBPα) is mutated in 6–10% of patients with acute myeloid leukaemia (AML). Recently, we reported the emergence of an N-terminal C/EBPα mutation after chemotherapy in a patient with secondary AML. The clone carrying the mutation became the dominant clone at relapse. This observation prompted us to compare the C/EBPα mutational status of 26 de novo non-core binding factor AML patients at diagnosis and at relapse after induction and consolidation chemotherapy. Four mutations in the C/EBPα gene were identified in two out of 26 patients. In both these cases, a biallelic mutation was present at diagnosis and at relapse: an amino-terminal frameshift mutation and a mutation of the fork/leucine finger 1 region. In patient 1, the amino-terminal frameshift mutation was duplicated and found on both alleles at relapse. In patient 2, the amino-terminal frameshift mutation and a mutation in the fork region were found either alone or combined on the same allele, suggesting a subclone formation. None of the patients without a C/EBPα mutation at diagnosis showed a mutation at relapse. This is the first report of an evolution of the C/EBPα gene between diagnosis and relapse in AML. [ABSTRACT FROM AUTHOR]

Background: Hypertrophic cardiomyopathy (HCM) is a genetic cardiomyopathy with a prevalence of about 1:200. It is characterized by left ventricular hypertrophy, diastolic dysfunction and interstitial fibrosis; HCM might lead to sudden cardiac death (SCD) especially in the young. Due to low autopsy frequencies of sudden unexplained deaths (SUD) the true prevalence of SCD and especially of HCM among SUD remains unclear. Even in cases of proven SCD genetic testing is not a routine procedure precluding appropriate risk stratification and counseling of relatives. Methods: Here we report a case of SCD in a 19‐year‐old investigated by combined forensic and molecular autopsy. Results: During autopsy of the index‐patient HCM was detected. As no other possible cause of death could be uncovered by forensic autopsy the event was classified as SCD. Molecular autopsy identified two (probably) pathogenic genetic variants in FHL1 and MYBPC3. The MYBPC3 variant had an incomplete penetrance. The FHL1 variant was a de novo mutation. We detected reduced FHL1 mRNA levels and no FHL1 protein in muscle samples suggesting nonsense‐mediated mRNA decay and/or degradation of the truncated protein in the SCD victim revealing a plausible disease mechanism. Conclusion: The identification of the genetic cause of the SCD contributed to the rational counseling of the relatives and risk assessment within the family. Furthermore our study revealed evidences for the pathomechanism of FHL1 mutations. [ABSTRACT FROM AUTHOR]

Fukutin encoded by FKTN is a ribitol 5-phosphate transferase involved in glycosylation of α-dystroglycan. It is known that mutations in FKTN affect the glycosylation of α-dystroglycan, leading to a dystroglycanopathy. Dystroglycanopathies are a group of syndromes with a broad clinical spectrum including dilated cardiomyopathy and muscular dystrophy. In this study, we reported the case of a patient with muscular dystrophy, early onset dilated cardiomyopathy, and elevated creatine kinase levels who was a carrier of the compound heterozygous variants p.Ser299Arg and p.Asn442Ser in FKTN. Our work showed that compound heterozygous mutations in FKTN lead to a loss of fully glycosylated α-dystroglycan and result in cardiomyopathy and end-stage heart failure at a young age. [ABSTRACT FROM AUTHOR]

Aims: Mechanical unloading by ventricular assist devices (VADs) has become increasingly important for the therapy of end‐stage heart failure during the last decade. However, VAD support was claimed to be associated with partial reverse remodelling. Unfortunately, the literature describes the contradictory effects of VAD systems on cardiac fibrosis, a hallmark of cardiac remodelling. To clarify these inconsistent results, the effects on cardiac fibrosis before and after mechanical unloading in 125 patients were examined. Methods and results: Left ventricular myocardial tissue from ischaemic or non‐ischaemic cardiomyopathy patients undergoing VAD implantation and subsequent cardiac transplantation and non‐failing hearts of the control group were analysed for 4‐hydroxyproline (4OH‐P) content as a marker for collagen protein. In addition, collagen cross‐linking and mRNAs of collagens I and III and transforming growth factor beta‐1 were measured. 4OH‐P content was significantly increased in failing hearts compared with the control group and increased (P < 0.05) after mechanical unloading (nmol/mg tissue, mean ± standard deviation: 16.74 ± 9.68 vs. 7.75 ± 2.39 and 18.57 ± 9.19). However, plotting of the 4OH‐P ratios (post/pre‐VAD) against the collagen content pre‐VAD could be fitted by non‐linear regression. Collagen cross‐linking correlated strongly with the total collagen content in pre‐ and post‐VAD myocardium (r2 = 0.73 and 0.71, respectively). In contrast to the total collagen content, all three mRNAs of fibrotic genes were significantly down‐regulated during VAD support when compared to pre‐VAD. Conclusions: This investigation of a comparably large patient cohort revealed that cardiac fibrosis was strongly increased in heart failure and increased even after mechanical unloading. The mRNAs of collagens I and III are independently regulated from the collagen protein. [ABSTRACT FROM AUTHOR]

We aimed to unravel the genetic, molecular and cellular pathomechanisms of DSC2 truncation variants leading to arrhythmogenic cardiomyopathy (ACM). We report a homozygous 4-bp DSC2 deletion variant c.1913_1916delAGAA, p.Q638LfsX647hom causing a frameshift carried by an ACM patient. Whole exome sequencing and comparative genomic hybridization analysis support a loss of heterozygosity in a large segment of chromosome 18 indicating segmental interstitial uniparental isodisomy (UPD). Ultrastructural analysis of the explanted myocardium from a mutation carrier using transmission electron microscopy revealed a partially widening of the intercalated disc. Using qRT-PCR we demonstrated that DSC2 mRNA expression was substantially decreased in the explanted myocardial tissue of the homozygous carrier compared to controls. Western blot analysis revealed absence of both full-length desmocollin-2 isoforms. Only a weak expression of the truncated form of desmocollin-2 was detectable. Immunohistochemistry showed that the truncated form of desmocollin-2 did not localize at the intercalated discs. In vitro , transfection experiments using induced pluripotent stem cell derived cardiomyocytes and HT-1080 cells demonstrated an obvious absence of the mutant truncated desmocollin-2 at the plasma membrane. Immunoprecipitation in combination with fluorescence measurements and Western blot analyses revealed an abnormal secretion of the truncated desmocollin-2. In summary, we unraveled segmental UPD as the likely genetic reason for a small homozygous DSC2 deletion. We conclude that a combination of nonsense mediated mRNA decay and extracellular secretion is involved in DSC2 related ACM. • We show that DSC2 truncating mutations cause a loss of function mechanism. • DSC2 truncating mutations can be recessively inherited. • First report, demonstrating that uniparental isodisomy might be involved in ACM. [ABSTRACT FROM AUTHOR]

In times of emerging multi-drug resistance among Gram-negative bacteria (including Salmonella enterica, Serovar Typhi), we observed relapse of typhoid fever following delayed response to treatment with meropenem, suggestive for limited clinical efficacy of the drug. Three previously published cases supported our suspicion. Within this context, we discuss the case details with a focus on potential explanations for insufficient clinical response to meropenem (e.g. limited intracellular penetration, phenomena of tolerance and persistence). Meropenem is a last-resort antimicrobial agent for the treatment of multi-drug resistant Gram-negative infections. Reliable clinical data evaluating the efficacy of meropenem for the treatment of typhoid fever are urgently needed. Future clinical studies evaluating typhoid fever outcome should also investigate the impact of (i) intracellular penetration of antibiotics, and (ii) tolerance and persistence on outcome. [ABSTRACT FROM AUTHOR]

A major cause of heart failure is cardiomyopathies, with dilated cardiomyopathy (DCM) as the most common form. Over 40 genes are linked to DCM, among them TTN and RBM20. Next Generation Sequencing in clinical DCM cohorts revealed truncating variants in TTN (TTNtv), accounting for up to 25% of familial DCM cases. Mutations in the cardiac splicing factor RNA binding motif protein 20 (RBM20) are also known to be associated with severe cardiomyopathies. TTN is one of the major RBM20 splicing targets. Most of the pathogenic RBM20 mutations are localized in the highly conserved arginine serine rich domain (RS), leading to a cytoplasmic mislocalization of mutant RBM20. Here, we present a patient with an early onset DCM carrying a combination of (likely) pathogenic TTN and RBM20 mutations. We show that the splicing of RBM20 target genes is affected in the mutation carrier. Furthermore, we reveal RBM20 haploinsufficiency presumably caused by the frameshift mutation in RBM20. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases are the number one cause of morbidity and mortality worldwide, but the underlying molecular mechanisms remain not well understood. Cardiomyopathies are primary diseases of the heart muscle and contribute to high rates of heart failure and sudden cardiac deaths. Here, we distinguished four different genetic cardiomyopathies based on gene expression signatures. In this study, RNA-Sequencing was used to identify gene expression signatures in myocardial tissue of cardiomyopathy patients in comparison to non-failing human hearts. Therefore, expression differences between patients with specific affected genes, namely LMNA (lamin A/C), RBM20 (RNA binding motif protein 20), TTN (titin) and PKP2 (plakophilin 2) were investigated. We identified genotype-specific differences in regulated pathways, Gene Ontology (GO) terms as well as gene groups like secreted or regulatory proteins and potential candidate drug targets revealing specific molecular pathomechanisms for the four subtypes of genetic cardiomyopathies. Some regulated pathways are common between patients with mutations in RBM20 and TTN as the splice factor RBM20 targets amongst other genes TTN, leading to a similar response on pathway level, even though many differentially expressed genes (DEGs) still differ between both sample types. The myocardium of patients with mutations in LMNA is widely associated with upregulated genes/pathways involved in immune response, whereas mutations in PKP2 lead to a downregulation of genes of the extracellular matrix. Our results contribute to further understanding of the underlying molecular pathomechanisms aiming for novel and better treatment of genetic cardiomyopathies. [ABSTRACT FROM AUTHOR]