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Doubly heterozygous LMNA and TTN mutations revealed by exome sequencing in a severe form of dilated cardiomyopathy.

ABSTRACT: 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.

SUBMITTER: Roncarati R

PROVIDER: S-EPMC3778353 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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An LMNA synonymous variant associated with severe dilated cardiomyopathy: Case report.

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Integrated analysis reveals the alterations that LMNA interacts with euchromatin in LMNA mutation-associated dilated cardiomyopathy.

Project description:BackgroundDilated cardiomyopathy (DCM) is a serious cardiac heterogeneous pathological disease, which may be caused by mutations in the LMNA gene. Lamins interact with not only lamina-associated domains (LADs) but also euchromatin by alone or associates with the lamina-associated polypeptide 2 alpha (LAP2α). Numerous studies have documented that LMNA regulates gene expression by interacting with LADs in heterochromatin. However, the role of LMNA in regulating euchromatin in DCM is poorly understood. Here, we determine the differential binding genes on euchromatin in DCM induced by LMNA mutation by performing an integrated analysis of bioinformatics and explore the possible molecular pathogenesis mechanism.ResultsSix hundred twenty-three and 4484 differential binding genes were identified by ChIP-seq technology. The ChIP-seq analysis results and matched RNA-Seq transcriptome data were integrated to further validate the differential binding genes of ChIP-seq. Five and 60 candidate genes involved in a series of downstream analysis were identified. Finally, 4 key genes (CREBBP, PPP2R2B, BMP4, and BMP7) were harvested, and these genes may regulate LMNA mutation-induced DCM through WNT/β-catenin or TGFβ-BMP pathways.ConclusionsWe identified four key genes that may serve as potential biomarkers and novel therapeutic targets. Our study also illuminates the possible molecular pathogenesis mechanism that the abnormal binding between LMNA or LAP2α-lamin A/C complexes and euchromatin DNA in LMNA mutations, which may cause DCM through the changes of CREBBP, PPP2R2B, BMP4, BMP7 expressions, and the dysregulation of WNT/β-catenin or TGFβ-BMP pathways, providing valuable insights to improve the occurrence and development of DCM.

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Upregulation of the aging related LMNA splice variant progerin in dilated cardiomyopathy.

Project description:Mutations in the LMNA gene are a common cause (6-8%) of dilated cardiomyopathy (DCM) leading to heart failure, a growing health care problem worldwide. The premature aging disease Hutchinson-Gilford syndrome (HGPS) is also caused by defined mutations in the LMNA gene resulting in activation of a cryptic splice donor site leading to a defective truncated prelamin A protein called progerin. Low levels of progerin are expressed in healthy individuals associated with ageing. Here, we aimed to address the role of progerin in dilated cardiomyopathy.mRNA expression of progerin was analyzed in heart tissue of DCM (n = 15) and non-failing hearts (n = 10) as control and in blood samples from patients with DCM (n = 56) and healthy controls (n = 10). Sequencing confirmed the expression of progerin mRNA in the human heart. Progerin mRNA levels derived from DCM hearts were significantly upregulated compared to controls (1.27 ± 0.42 vs. 0.81 ± 0.24; p = 0.005). In contrast, progerin mRNA levels in whole blood cells were not significantly different in DCM patients compared to controls. Linear regression analyses revealed that progerin mRNA in the heart is significantly negatively correlated to ejection fraction (r = -0.567, p = 0.003) and positively correlated to left ventricular enddiastolic diameter (r = 0.551, p = 0.004) but not with age of the heart per se. Progerin mRNA levels were not influenced by inflammation in DCM hearts. Immunohistochemistry and Immunofluorescence analysis confirmed increased expression of progerin protein in cell nuclei of DCM hearts associated with increased TUNEL+ apoptotic cells.Our data suggest that progerin is upregulated in human DCM hearts and strongly correlates with left ventricular remodeling. Progerin might be involved in progression of heart failure and myocardial aging.

| S-EPMC5922532 | biostudies-other

LMNA gene single nucleotide polymorphisms in dilated cardiomyopathy of Han children.

Project description:ObjectiveTo investigate whether LMNA gene mutation is associated with dilated cardiomyopathy (DCM) in Chinese Han Race children.MethodsDNA was isolated from 78 patients with DCM and 100 healthy Chinese children who served as controls. 12 exons in the functional regions and the adjacent part of introns of the LMNA gene were amplified with polymerase chain reactions (PCR) and the PCR products were sequenced with DNA sequencer. We compared the DNA sequence with Blast software online PubMed website. The differences of allele and genotype between the groups were detected by χ(2) test.ResultsNo disease-causing mutation in LMNA gene was found in all DCM patients. Three nonsense single nucleotide polymorphisms (SNPs) were identified. ① The first is c.1908C>T (H566H, rs4641) which was located at exon 10 of LMNA gene. It was found in 29 DCM cases and 15 control subjects. Compared to healthy controls, the frequency of TT and TC genotypes, and the C allele were significantly increased in DCM patients (P<0.05). ② The second was c.861C>T (A287A, rs5380) which was located at exon 5 of LMNA gene. It was found in 9 DCM cases and 2 control subjects. The frequency of TC genotype was significantly increased in DCM patients (P<0.05). ③ The third was c.1338C>T (D446D, rs5058) which located at exon 7 of LMNA gene. It was found in 8 DCM cases and 3 control subjects. The frequency of TC genotype was significantly increased in DCM patients (P<0.05).ConclusionThe SNP of LMNA gene may be associated with the susceptivity of DCM in Chinese Han children.

| S-EPMC4565312 | biostudies-literature

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