BACKGROUND Mutation in the titin gene(TTN)in left ventricular noncompaction(LVNC)has been reported with a highly heterogeneous prevalence,and the molecular mechanisms underlying the pathogenesis of TTN gene mutation a...BACKGROUND Mutation in the titin gene(TTN)in left ventricular noncompaction(LVNC)has been reported with a highly heterogeneous prevalence,and the molecular mechanisms underlying the pathogenesis of TTN gene mutation are uncharacteri-zed.In the present study,we identified a novel TTN mutation in a pedigree with LVNC and investigated the potential pathogenic mechanism by functional studies.METHODS The whole-genome sequencing with linkage analysis was performed in a 3-generation family affected by autoso-mal dominant LVNC cardiomyopathy.The clustered regularly interspaced short palindromic repeats associated protein 9(CRISPR/Cas9)technology was used to establish novel truncating mutation in TTN in a rat cardiomyoblast H9C2 cell line in vitro,in which functional studies were carried out and characterized in comparison to its wild-type counterpart.RESULTS A novel truncating mutation TTN p.R2021X was identified as the only plausible disease-causing variant that segreg-ated with disease among the five surviving affected individuals,with an interrogation of the entire genome excluding other po-tential causes.Quantitative reverse transcription-polymerase chain reaction and cellular immunofluorescence supported a haplo-insufficient disease mechanism in titin truncation mutation cardiomyocytes.Further functional studies suggested mitochondrial abnormities in the presence of mutation,including decreased oxygen consumption rate,reduced adenosine triphosphate produc-tion,impaired activity of electron translation chain,and abnormal mitochondrial structure on electron microscopy.Impaired aut-ophagy under electron microscopy accompanied with activation of the Akt-mTORC1 signaling pathway was observed in TTN p.R2021X truncation mutation cardiomyocytes.CONCLUSIONS The TTN p.R2021X mutation has a function in the cause of a highly penetrant familial LVNC.These findings expand the spectrum of titin’s roles in cardiomyopathies and provide novel insight into the molecular basis of titin-truncating variants-associated LVNC.展开更多
BACKGROUND Left ventricular noncompaction(LVNC) is an increasingly recognised cardiomyopathy of which a significant percentage are genetic in origin. The purpose of the present study was to identify potential pathogen...BACKGROUND Left ventricular noncompaction(LVNC) is an increasingly recognised cardiomyopathy of which a significant percentage are genetic in origin. The purpose of the present study was to identify potential pathogenic mutation leading to disease in a Chinese LVNC family.METHODS A 3-generation family affected by LVNC was recruited. Clinical assessments were performed on available family members, with clinical examination, ECG, echocardiography and cardiac MRI. The proband(Ⅰ-2), the proband’s daughter(Ⅱ-1, affected) and mother(Ⅲ-1, unaffected) were selected for WGS. Sanger sequencing were performed in all of the 4 surviving family members.RESULTS Combined whole genome sequencing with linkage analysis identified a novel missense mutation in the giant protein obscurin(OBSCN NM_001098623, c.C19063T), as the only plausible disease-causing variant that segregates with disease among the four surviving individuals, with interrogation of the entire genome excluding other potential causes. This c.C19063T missense mutation resulted in p.R6355W in the encoded OBSCN protein. It affected a highly conserved residue in the C terminus of the obscurin-B-like isoform between the PH and STKc domains, which was predicted to affect the function of the protein by different bioinformatics tools.CONCLUSIONS Here we present clinical and genetic evidence implicating the novel R6355W missense mutation in obscurin as the cause of familial LVNC. This expands the spectrum of obscurin’s roles in cardiomyopathies. It furthermore highlights that rare obscurin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here. This study also provided new insights into the molecular basis of OBSCN mutation positive LVNC.展开更多
Background:Desminopathy, a hereditary myofibrillar myopathy, mainly results from the desmin gene (DES) mutations.Desminopathy involves various phenotypes, mainly including different cardiomyopathies, skeletal myopathy...Background:Desminopathy, a hereditary myofibrillar myopathy, mainly results from the desmin gene (DES) mutations.Desminopathy involves various phenotypes, mainly including different cardiomyopathies, skeletal myopathy, and arrhythmia.Combined with genotype, it helps us precisely diagnose and treat for desminopathy.Methods:Sanger sequencing was used to characterize DES variation, and then a minigene assay was used to verify the effect of splice-site mutation on pre-mRNA splicing.Phenotypes were analyzed based on clinical characteristics associated with desminopathy.Results:A splicing mutation (c.735+1G>T) in DES was detected in the proband.A minigene assay revealed skipping of the whole exon 3 and transcription of abnormal pre-mRNA lacking 32 codons.Another affected family member who carried the identical mutation, was identified with a novel phenotype of desminopathy, non-compaction of ventricular myocardium.There were 2 different phenotypes varied in cardiomyopathy and skeletal myopathy among the 2 patients, but no significant correlation between genotype and phenotype was identified.Conclusions:We reported a novel phenotype with a splicing mutation in DES, enlarging the spectrum of phenotype in desminopathy.Molecular studies of desminopathy should promote our understanding of its pathogenesis and provide a precise molecular diagnosis of this disorder, facilitating clinical prevention and treatment at an early stage.展开更多
基金supported by the National Key Research and Development Program of China(2016 YFC1300100)the National Natural Science Foundation of China(No.81974042)+1 种基金the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2019XK320058)the Peking Union Medical College Youth Fund(No.3332018058).
文摘BACKGROUND Mutation in the titin gene(TTN)in left ventricular noncompaction(LVNC)has been reported with a highly heterogeneous prevalence,and the molecular mechanisms underlying the pathogenesis of TTN gene mutation are uncharacteri-zed.In the present study,we identified a novel TTN mutation in a pedigree with LVNC and investigated the potential pathogenic mechanism by functional studies.METHODS The whole-genome sequencing with linkage analysis was performed in a 3-generation family affected by autoso-mal dominant LVNC cardiomyopathy.The clustered regularly interspaced short palindromic repeats associated protein 9(CRISPR/Cas9)technology was used to establish novel truncating mutation in TTN in a rat cardiomyoblast H9C2 cell line in vitro,in which functional studies were carried out and characterized in comparison to its wild-type counterpart.RESULTS A novel truncating mutation TTN p.R2021X was identified as the only plausible disease-causing variant that segreg-ated with disease among the five surviving affected individuals,with an interrogation of the entire genome excluding other po-tential causes.Quantitative reverse transcription-polymerase chain reaction and cellular immunofluorescence supported a haplo-insufficient disease mechanism in titin truncation mutation cardiomyocytes.Further functional studies suggested mitochondrial abnormities in the presence of mutation,including decreased oxygen consumption rate,reduced adenosine triphosphate produc-tion,impaired activity of electron translation chain,and abnormal mitochondrial structure on electron microscopy.Impaired aut-ophagy under electron microscopy accompanied with activation of the Akt-mTORC1 signaling pathway was observed in TTN p.R2021X truncation mutation cardiomyocytes.CONCLUSIONS The TTN p.R2021X mutation has a function in the cause of a highly penetrant familial LVNC.These findings expand the spectrum of titin’s roles in cardiomyopathies and provide novel insight into the molecular basis of titin-truncating variants-associated LVNC.
基金supported by the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (2019XK320057)the National Key Research and Development Program of China (2016YFC1300100)+1 种基金the Clinical Transformation and Transformation Fund of the Chinese Academy of Medical Sciences (2019XK320058)the National Natural Science Foundation of China (81974042)
文摘BACKGROUND Left ventricular noncompaction(LVNC) is an increasingly recognised cardiomyopathy of which a significant percentage are genetic in origin. The purpose of the present study was to identify potential pathogenic mutation leading to disease in a Chinese LVNC family.METHODS A 3-generation family affected by LVNC was recruited. Clinical assessments were performed on available family members, with clinical examination, ECG, echocardiography and cardiac MRI. The proband(Ⅰ-2), the proband’s daughter(Ⅱ-1, affected) and mother(Ⅲ-1, unaffected) were selected for WGS. Sanger sequencing were performed in all of the 4 surviving family members.RESULTS Combined whole genome sequencing with linkage analysis identified a novel missense mutation in the giant protein obscurin(OBSCN NM_001098623, c.C19063T), as the only plausible disease-causing variant that segregates with disease among the four surviving individuals, with interrogation of the entire genome excluding other potential causes. This c.C19063T missense mutation resulted in p.R6355W in the encoded OBSCN protein. It affected a highly conserved residue in the C terminus of the obscurin-B-like isoform between the PH and STKc domains, which was predicted to affect the function of the protein by different bioinformatics tools.CONCLUSIONS Here we present clinical and genetic evidence implicating the novel R6355W missense mutation in obscurin as the cause of familial LVNC. This expands the spectrum of obscurin’s roles in cardiomyopathies. It furthermore highlights that rare obscurin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here. This study also provided new insights into the molecular basis of OBSCN mutation positive LVNC.
基金grants from CAMS Innovation Fund for Medical Sciences (No.2016-I2M-1-002)the National Key Research and Development Program of China (No.2016YFC1300100)+2 种基金National Natural Science Foundation of China (No.81600305,No. 81400187)Beijing Municipal Science and Technology Commission (No.Z151100003915078)PUMC Graduate Innovation Fund (2018-1002-01-14).
文摘Background:Desminopathy, a hereditary myofibrillar myopathy, mainly results from the desmin gene (DES) mutations.Desminopathy involves various phenotypes, mainly including different cardiomyopathies, skeletal myopathy, and arrhythmia.Combined with genotype, it helps us precisely diagnose and treat for desminopathy.Methods:Sanger sequencing was used to characterize DES variation, and then a minigene assay was used to verify the effect of splice-site mutation on pre-mRNA splicing.Phenotypes were analyzed based on clinical characteristics associated with desminopathy.Results:A splicing mutation (c.735+1G>T) in DES was detected in the proband.A minigene assay revealed skipping of the whole exon 3 and transcription of abnormal pre-mRNA lacking 32 codons.Another affected family member who carried the identical mutation, was identified with a novel phenotype of desminopathy, non-compaction of ventricular myocardium.There were 2 different phenotypes varied in cardiomyopathy and skeletal myopathy among the 2 patients, but no significant correlation between genotype and phenotype was identified.Conclusions:We reported a novel phenotype with a splicing mutation in DES, enlarging the spectrum of phenotype in desminopathy.Molecular studies of desminopathy should promote our understanding of its pathogenesis and provide a precise molecular diagnosis of this disorder, facilitating clinical prevention and treatment at an early stage.