Clinical Impact of Secondary Risk Factors in TTN-Mediated Dilated Cardiomyopathy.
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ABSTRACT:
SUBMITTER: Giudicessi JR
PROVIDER: S-EPMC8284363 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Truncating variants in TTN (TTNtv), coding for the largest structural protein in the sarcomere, contribute to the largest portion of familial and ambulatory dilated cardiomyopathy (DCM). TTN haploinsufficiency caused by TTNtv is suggested as the disease mechanism. However, it is unclear whether TTN insufficiency causes DCM. Moreover, it is unknown whether modulation of downstream pathways serves as a therapeutic strategy for DCM caused by TTN insufficiency. Here, we show that reduction of cardiac Ttn expression by adeno-associated virus mediated shRNA (Ttn shRNA) generated DCM in mouse, demonstrating impaired cardiac performance, enlarged left ventricle (LV) and reduced LV wall thickness. A screen of 10 dysregulated and selected genes identified that Yin Yang 1 (Yy1) significantly suppressed DCM caused by Ttn shRNA. Gene profiling by RNAseq showed Yy1 modulated cell growth related genes. Ttn insufficiency activated cardiomyocyte cell cycle reentry by upregulating of Ccnd1 and Ccnd2. Cardiomyocytes activated by Ttn insufficiency did not advance to S phase by EdU incorporation assay. Yy1 promoted cardiomyocyte cell cycle by further enhancing Ccnd1 and Ccnd2 and increasing DNA replication without undergoing cell division. Importantly, upregulation of Ccnd1 and Ccnd2 suppressed DCM caused by Ttn insufficiency. Our findings demonstrate that DCM caused by Ttn insufficiency can be treated by therapeutically promoting cardiac cell cycle.
| S-EPMC6841687 | biostudies-literature
Project description:The mutations of TTN gene that encodes titin are the most common mutation type among the genetic causes of dilated cardiomyopathy (DCM). This article reviews the worldwide studies on potential molecular pathogenesis (transcription, post-translational modification, etc.), clinical phenotypes, and gene therapies of pediatric DCM caused by TTN mutations, with the hope of providing a reference for the precision treatment of pediatric DCM caused by TTN mutations.
| S-EPMC9979384 | biostudies-literature
Project description:A 6-month-old infant boy presented with symptomatic heart failure. Dilated cardiomyopathy was found in association with a mutation in TTN. Structural heart disease included novel septation of the left ventricle with a fenestrated membrane resulting from aberrant congenital mitral valve apparatus formation. (Level of Difficulty: Advanced.).
| S-EPMC8571792 | biostudies-literature
Project description:Background: Mutations in the TTN gene are the most common causes of dilated cardiomyopathy (DCM). The clinical significance of TTN gene variants remains inadequately understood. Methods: Whole-exome sequencing and phenotypic characterisation were performed, and patients were followed up for a median of 44 months. Results: We analyzed the association of the TTN variants with the clinical outcomes in a prospective study of 1,041 patients with sporadic DCM. TTN truncating variants (tTTN) were detected in 120 (11.5%) patients as compared with 2.4/10,000 East Asian populations in the Genome Aggregation Database (GnomAD; p < 0.0001). Pathogenic TTN missense variants were also enriched in DCM as compared with the GnomAD populations (27.6 vs. 5.9%, p < 0.0001). DCM patients with tTTN had a lower left ventricular ejection fraction (28.89 ± 8.72 vs. 31.81 ± 9.97, p = 0.002) and a lower frequency of the left bundle branch block (3.3 vs. 11.3%, p = 0.011) than those without or with mutations in other known causal genes (OCG). However, tTTN were not associated with the composite primary endpoint of cardiac death and heart transplantation during the follow-up period [adjusted hazard ratio (HR): 0.912; 95% confidence interval: 0.464-1.793; p = 0.790]. There was also no sex-dependent effect. Concomitant tTTN and pathogenic variants in OCG were present in only eight DCM patients and did not affect the outcome. Conclusion: The phenotype of DCM caused by tTTN, major causes of sporadic DCM, is not distinctly different from those caused by other causal genes for DCM.
| S-EPMC8120103 | biostudies-literature
Project description:BACKGROUND:Pathogenic variants in TTN (OMIM 188840), encoding the largest human protein, are known to cause dilated cardiomyopathy and several forms of skeletal myopathy. The clinical interpretation of TTN variants is challenging, however, due to the frequency of missense changes, variable testing and reporting practices in commercial laboratories, and incomplete understanding of the spectrum of TTN-related disease. METHODS:We report a heterozygous TTN deletion segregating in a family with an unusual skeletal myopathy phenotype associated with facial weakness, gait abnormality, and dilated cardiomyopathy. RESULTS:A novel 16.430 kb heterozygous deletion spanning part of the A- and M-bands of TTN was identified in the proband and his symptomatic son, as well as in an additional son whose symptoms were identified on clinical evaluation. The deletion was found to be de novo in the proband. CONCLUSION:Pathogenic variants in TTN may be an unrecognized cause of skeletal myopathy phenotypes, particularly when accompanied by dilated cardiomyopathy.
| S-EPMC6825852 | biostudies-literature
Project description:Dilated cardiomyopathy (DCM) is a common heart disease that can lead to heart failure and sudden cardiac death. Mutations in the TTN gene are the most frequent cause of DCM. Here, we generated two human induced pluripotent stem cell (iPSC) lines from the peripheral blood mononuclear cells (PBMCs) of two DCM patients carrying c.94816C>T and c.104188A>G mutations in TTN, respectively. The two lines exhibited a normal morphology, full expression of pluripotency markers, a normal karyotype and the ability of trilineage differentiation. The two lines can serve as useful tools for drug screening and mechanism studies on DCM.
| S-EPMC9870071 | biostudies-literature
Project description:Dilated cardiomyopathy (DCM), defined by left ventricular (LV) enlargement associated with impaired cardiac performance, is a major cause of heart failure (HF). This results in a dilated, thin-walled left ventricle that fails to supply sufficient blood to the body. Truncating variants in TTN (TTNtv), coding for the largest structural protein in the sarcomere, contribute to the largest portion of familial and ambulatory DCM. The mechanisms for how TTNtv lead to cardiac dilation are unclear. Here, we show that reduction of Ttn expression by shRNA (Ttn shRNA) generated DCM in both mouse and rat. Ttn shRNA transduced mice developed typical DCM manifestations including impaired cardiac performance, enlarged LV and reduced LV wall thickness. Gene profiling indicates cardiac metabolism, cell proliferation and survival related genes are significantly dysregulated in Ttn shRNA-induced DCM. TUNEL assay showed Ttn shRNA induced a significant increase of cardiac cell apoptosis. A screen of 15 dysregulated downstream genes identified candidates, including Esrra, Esrrb and Yy1 significantly suppressed Ttn shRNA-induced cardiac dilation and/or DCM. Ttn shRNA induced cardiac cell apoptosis was ameliorated by Yy1. Importantly, by inducing D-type cyclin, Yy1 initiated cardiomyocyte cell cycle reentry facilitating the restoration of cardiac performance. Our findings demonstrate that DCM caused by Ttn insufficiency can be treated by therapeutically enhancing cardiac cell proliferation and survival.
2020-03-26 | GSE112319 | GEO
Project description:Idiopathic dilated cardiomyopathy (DCM) is a common cardiomyopathy with the prevalence of 1:250, and at least one-third of all the cases are inherited. Mutations in the TTN gene are considered as the most frequent cause of inherited DCM and cover 10-30% of the cases. The studies were mainly focused on the adult or mixed age group of patients with DCM. The mutation rate in the TTN gene, the characteristics of manifestations and their prognostic significance in childhood have not been studied. To determine TTN mutation rate in children with DCM and the relevance of including this gene in the DNA diagnostic protocol for paediatric DCM, complete clinical and instrumental examination of 36 DCM patients (up to 18 years) with the manifestation of the disease was conducted in specialised cardiology centres. Molecular genetic testing included sequencing of coding and adjacent regulatory regions of the major cardiac TTN isoform N2BA using IonTorrent ™ semiconductor sequencing (for 25 isolated cases) and trio whole exome sequencing (trio WES)on the Illumina platform (for 11 family cases). Our pilot group included 36 probands with DCM diagnosis first established on the basis of the generally accepted criteria at the age of 5 days to 18 years(average age: 6.5 years). The sex ratio (M:F) was 23: 8. There were 25 sporadic DCM cases and 11 cases of familial DCM (at least one of the parents and/or siblings were also diagnosed with DCM). The only likely pathogenic truncating variant p.Arg33703*in the TTN gene (TTNtv) was found in a 16-year-oldmale proband out of 36 (3%). Apparently, TTN-dependent forms of DCMs manifest later at a young (but older than 18 years) or more mature age, and TTN gene cannot be considered as the first-line genetic testing for DCM in the paediatric group, despite several studies have reported a generally high mutation rate in this gene with DCM. Further research is needed to compare the representation of mutations in the TTN gene in different age groups of DCM patients.
| S-EPMC6848193 | biostudies-literature
Project description:Both genetic and environmental factors contribute to the development of dilated cardiomyopathy. Among the genes involved, TTN mutations, including truncated variants, explain 25% of DCM cases. We performed genetic counseling and analysis on a 57-year-old woman diagnosed with severe DCM and presenting relevant acquired risk factors for DCM (hypertension, diabetes, smoking habit, and/or previous alcohol and cocaine abuse) and with a family history of both DCM and sudden cardiac death. The left ventricular systolic function, as assessed by standard echocardiography, was 20%. The genetic analysis performed using TruSight Cardio panel, including 174 genes related to cardiac genetic diseases, revealed a novel nonsense TTN variant (TTN:c.103591A > T, p.Lys34531*), falling within the M-band region of the titin protein. This region is known for its important role in maintaining the structure of the sarcomere and in promoting sarcomerogenesis. The identified variant was classified as likely pathogenic based on ACMG criteria. The current results support the need of genetic analysis in the presence of a family history, even when relevant acquired risk factors for DCM may have contributed to the severity of the disease.
| S-EPMC10047881 | biostudies-literature
Project description:Familial dilated cardiomyopathy (DCM) is a heterogeneous disease; although 30 disease genes have been discovered, they explain only no more than half of all cases; in addition, the causes of intra-familial variability in DCM have remained largely unknown. In this study, we exploited the use of whole-exome sequencing (WES) to investigate the causes of clinical variability in an extended family with 14 affected subjects, four of whom showed particular severe manifestations of cardiomyopathy requiring heart transplantation in early adulthood. This analysis, followed by confirmative conventional sequencing, identified the mutation p.K219T in the lamin A/C gene in all 14 affected patients. An additional variant in the gene for titin, p.L4855F, was identified in the severely affected patients. The age for heart transplantation was substantially less for LMNA:p.K219T/TTN:p.L4855F double heterozygotes than that for LMNA:p.K219T single heterozygotes. Myocardial specimens of doubly heterozygote individuals showed increased nuclear length, sarcomeric disorganization, and myonuclear clustering compared with samples from single heterozygotes. In conclusion, our results show that WES can be used for the identification of causal and modifier variants in families with variable manifestations of DCM. In addition, they not only indicate that LMNA and TTN mutational status may be useful in this family for risk stratification in individuals at risk for DCM but also suggest titin as a modifier for DCM.
| S-EPMC3778353 | biostudies-literature