OBJECTIVETo study cardiac troponin T (TNNT2) gene mutations in Chinese patients with hypertrophic cardiomyopathy (HCM) and analyze the correlation between the genotype and phenotype.

METHODSNinety-five unrelated Chinese patients with HCM and 120 control individuals were screened for TNNT2 gene mutations. Seven exons (8, 9, 10, 11, 14, 15, and 16) in the functional regions of TNNT2 gene were amplified using PCR and the products were sequenced. The patients with positive results underwent further family screening.

RESULTS AND CONCLUSIONThis study did not find any HCM-caused mutations in TNNT2 gene, a result different from the reported rates of TNNT2 gene mutation ranging from 10% to 20% in other nations, suggesting that TNNT2 gene is not a susceptible gene for HCM in Chinese population.

Asian Continental Ancestry Group ; genetics ; Cardiomyopathy, Hypertrophic ; genetics ; Case-Control Studies ; Humans ; Mutation ; Troponin T ; genetics

Cardiomyopathy, Hypertrophic ; epidemiology ; genetics ; China ; epidemiology ; Humans ; Mutation ; Prevalence ; Troponin T ; genetics

OBJECTIVERestrictive cardiomyopathy (RCM) is rare in children, and little is known about the molecular basis of RCM. The aim of this study was to investigate the clinical and myopathological characteristics and to detect mutations on cardiac sarcomere protein genes in three idiopathic pediatric RCMs.

METHODSDetailed clinical characteristics and familiar history were obtained in three idiopathic pediatric RCMs. One hundred healthy pediatric individuals were recruited as controls. Histological evaluation was performed with heart tissue retrieved at catheterization in case-1 and case-2. The entire coding sequences of four cardiac sarcomere protein genes, including cardiac troponin T (TNNT2), cardiac troponin I(TNNI3), β-myosin heavy chain (MYH7), and α-actin (ACTC)were screened for mutations. Sequence variants were then tested in the family as well as in 100 healthy control DNAs.

RESULTSAll three index cases were diagnosed as primary RCMs without family history, and their clinical conditions deteriorated rapidly. Case-1 was in combination with ventricular septal defect. Case-2 was in combination with mid- and inferoseptal hypertrophy. In case-1, myocardial biopsies displayed extensive an isomorphism and disarray of cardiomyocytes; electron microscopy showed large stacks of severely dysmorphic megamitochondria and focal Z-disc streaming. In case-2, endomyocardial biopsy revealed moderate myocyte hypertrophy with mild interstitial fibrosis; transmission electron microscopy showed misalignment of Z-bands and unequal Z-Z band distances. Genetic analysis identified two heterozygous missense mutations in TNNI3, with R204H in case-1 and R192H in case-3 respectively. A de novo heterozygous deletion in TNNT2 (p. Asn100_Glu101del) was identified in case-2. Sequence analysis shows that all three mutations are located in a position highly conserved across many species. The three mutations were negative for their parents and controls.

CONCLUSIONThe clinical conditions in all three index cases are deteriorated rapidly after diagnosed as primary RCM. Three heterozygous mutations including two in TNNI3 and one in TNNT2 gene are identified in the three RCMs respectively, which are considered as causative mutations. These findings provide new insights into the molecular etiology responsible for pediatric RCM.

Amino Acid Sequence ; Cardiomyopathy, Restrictive ; genetics ; Child ; DNA Mutational Analysis ; Female ; Humans ; Molecular Sequence Data ; Mutation ; Troponin I ; genetics ; Troponin T ; genetics

Hypertrophic cardiomyopathy (HCM) is the most common monogenic inherited myocardial disease in children, and mutations in sarcomere genes (such as MYH7 and MYBPC3) are the most common genetic etiology of HCM, among which mutations in the MYH7 gene are the most common and account for 30%-50%. MYH7 gene mutations have the characteristics of being affected by environmental factors, coexisting with multiple genetic variations, and age-dependent penetrance, which leads to different or overlapping clinical phenotypes in children, including various cardiomyopathies and skeletal myopathies. At present, the pathogenesis, course, and prognosis of HCM caused by MYH7 gene mutations in children remain unclear. This article summarizes the possible pathogenesis, clinical phenotype, and treatment of HCM caused by MYH7 gene mutations, in order to facilitate the accurate prognostic evaluation and individualized management and treatment of the children with this disorder.
Child ; Humans ; Cardiomyopathy, Hypertrophic/therapy* ; Phenotype ; Troponin T/genetics* ; Mutation ; Carrier Proteins/genetics* ; Myosin Heavy Chains/genetics* ; Cardiac Myosins/genetics*

Adolescent ; Adult ; Aged ; Cardiomyopathy, Hypertrophic ; genetics ; Child ; Child, Preschool ; Female ; Humans ; Male ; Middle Aged ; Mutation ; Troponin T ; genetics

AIMTo analyze the distribution of single nucleotide polymorphisms in Han ethnic population from Northern China.

METHODSAllele frequencies in a sample of healthy Chinese Hans (n = 204) were determined by polymerase chain reactions followed by restriction analyses with specific endonucleases.

RESULTSThe SNP 27916722 A/C in exon 11 from the NCBI database was not detected in this population. And there were significant differences between the allele frequencies of the SNPs (27930097 C/G and 27920978 C/T) in Han ethnic population from Northern China and those in the NCBI.

CONCLUSIONIt is suggested that the SNPs of sTnT are different in different ethnic populations.

Adolescent ; Adult ; Ethnic Groups ; genetics ; Exons ; Female ; Gene Frequency ; Genotype ; Humans ; Male ; Polymorphism, Single Nucleotide ; Troponin T ; classification ; genetics

OBJECTIVETo screen the cardiac troponin T (TNNT2) mutations in Chinese patients with hypertrophic cardiomyopathy (HCM) and to analyze the potential link between the genotype and the phenotype.

METHODSClinical features of 100 probands with HCM and some family members were evaluated, 200 unrelated normal subjects served as control. The exons and flanking introns of TNNT2 were amplified with PCR and direct sequencing was used to screen TNNT2 mutations/polymorphisms.

RESULTSTwo novel missense mutations were detected in 2 HCM patients: R92W and R286H. These 2 mutations were not found in 200 non-HCM controls. A five-basepair insertion/deletion polymorphism in intron 3 of TNNT2 was identified in this HCM cohort but was not related to the phenotype.

CONCLUSIONSTwo missense mutations, R92W and R286H, were found in 2/100 patients with HCM, TNNT 2 mutation is relatively low in Chinese patients with HCM.

Asian Continental Ancestry Group ; Cardiomyopathy, Hypertrophic ; genetics ; Case-Control Studies ; Exons ; Genotype ; Humans ; Mutation ; Mutation, Missense ; Pedigree ; Phenotype ; Polymorphism, Genetic ; Troponin T ; genetics

Cardiac troponin T (cTnT) serves as a structural protein of myocardial fiber, and participates in heart excitation-contraction coupling process. Here, we generated tnnt2a (cTnT-coding gene) deletion mutant zebrafish via CRISPR/Cas9 technique, and performed phenotypic analysis of the identified tnnt2a mutants. We observed that there was no significant difference between heterozygous mutant and wild type zebrafish, and the homozygous mutants displayed significant malformations in heart, including cardiac arrest, atrium and ventricle enlargement, pericardium effusion, and the individuals usually died before 7 day post fertilization (dpf). We further analyzed the expression alternations of heart sarcomere genes (tnnt2a, actc1a, tpm4a, myl7, vmhc) at transcriptional level in tnnt2a(Δ2) zebrafish by performing real time RT-PCR, and found that the RNA expression level of tnnt2a in tnnt2azebrafish decreased constantly at each time point of developmental stages, and actc1a, tpm4a, myl7 and vmhc all showed higher expressions at early developmental stages and lower expressions at late developmental stages, in comparison with those of wild type zebrafish. Lastly, electron microscopy on cardiac tissues suggested that there were significant changes of the thick or thin filament structures in tnnt2a(Δ2) zebrafish, which was further confirmed by F-actin and Tpm4 immunofluorescence staining. The tnnt2azebrafish generated by CRISPR/Cas9 bears the most common symptoms of patients with dilated cardiomyopathy, and therefore can be used as a tool to study TNNT2-deficiency related cardiomyopathy.
Animals ; CRISPR-Cas Systems ; Disease Models, Animal ; Gene Knockout Techniques ; Myocardium ; pathology ; Sequence Deletion ; Troponin T ; genetics ; Zebrafish ; Zebrafish Proteins ; genetics

OBJECTIVETo reveal genotype-phenotype correlation of disease-causing gene mutations in Chinese hypertrophic cardiomyopathy (HCM) pedigree.

METHODSPeripheral venous blood samples were collected from two Chinese HCM families and 120 healthy subjects were recruited as normal control. The full encoding exons and flanking sequences of the cardiac troponin T gene (TNNT2), beta-myosin heavy chain gene (MYH7) and myosin binding protein C gene (MYBPC3) were amplified with the polymerase chain reaction method, DNA sequencing was used to detect the mutation.

RESULTSIn ZZJ family, mutation G12101A was identified in exon 21 of MYBPC3 gene in 4 family members [the arginine (R) converted to histidine (H)]. In this pedigree, three out of eight family members were diagnosed as HCM and with a penetrance of 75%. In FHL family, mutation G15391A was identified in exon 23 of MYH7 gene in 3 family members [the glutamic acid (E) converted to lysine (K)]. In this pedigree, three out of six family members were diagnosed as HCM and with a penetrance of 100%. Echocardiography showed obstruction of left ventricular outflow tract in two out of the three HCM patients.

CONCLUSIONSOur results showed that the G12101A mutation of MYBPC3 gene is the causal mutation of familial HCM with mild phenotype. The G15391A mutation of MYH7 gene is the causal mutation of familial HCM with malignant phenotype and a penetrance of 100%. Screening mutations in the MYH7 gene should be viewed as a reasonable procedure in obstructive HCM patients.

Asian Continental Ancestry Group ; genetics ; Cardiac Myosins ; genetics ; Cardiomyopathy, Hypertrophic, Familial ; ethnology ; genetics ; Carrier Proteins ; genetics ; DNA Mutational Analysis ; Exons ; Female ; Gene Frequency ; Genotype ; Humans ; Male ; Mutation ; Myosin Heavy Chains ; genetics ; Pedigree ; Phenotype ; Troponin T ; genetics

OBJECTIVEThe aim of this study was to screen the disease-causing gene mutations and investigate the genotype-phenotype correlation in 10 Chinese pedigrees with familial hypertrophic cardiomyopathy (HCM).

METHODSThere are 91 family members from these 10 pedigrees and 5 members were normal mutated carriers, 23 members were HCM patients (14 male) aged from 1.5 to 73 years old. The functional regions of myosin heavy chain gene (MYH7), cardiac myosin-binding protein C (MYBPC3) and cardiac troponin T gene (TNNT2) were screened with PCR and direct sequencing technique. Clinical information from all patients was also evaluated in regard to the genotype.

RESULTSMutations were found in 5 out of 10 pedigrees. Mutations in MYH7 (Arg663His, Glu924Lys and Ile736Thr) were found in 3 pedigrees and 3 patients from these pedigrees suffered sudden death at age 20-48 years old during sport. Mutations in MYBPC3 were found in 2 pedigrees, 1 with complex mutation (Arg502Trp and splicing mutation IVS27 + 12C > T) and 1 with novel frame shift mutation (Gly347fs) and the latter pedigree has sudden death history. No mutation was identified in TNNT2.

CONCLUSIONSAlthough the Han Chinese is a relatively homogeneous ethnic group, different HCM gene mutations were responsible for familiar HCM suggesting the heterogeneity nature of the disease-causing genes and HCM MYH7 mutations are associated with a higher risk of sudden death in this cohort. Furthermore, identical mutation might result in different phenotypes suggesting that multiple factors might be involved in the pathogenesis of familiar HCM.

Adolescent ; Adult ; Aged ; Asian Continental Ancestry Group ; genetics ; Cardiac Myosins ; genetics ; Cardiomyopathy, Hypertrophic, Familial ; ethnology ; genetics ; Carrier Proteins ; genetics ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Middle Aged ; Mutation ; Myosin Heavy Chains ; genetics ; Pedigree ; Phenotype ; Troponin T ; genetics ; Young Adult