Clinical and genetic characteristics of different types of non-obstructive hypertrophic cardiomyopathy / 中华心血管病杂志

Objective: To analyze the clinical and genetic characteristics of clinical subtypes of non-obstructive hypertrophic cardiomyopathy (HCM). Methods: It was a cohort study. Patients with non-obstructive HCM admitted to Fuwai Hospital, Chinese Academy of Medical Sciences, from January 1999 to April 2019 were enrolled. According to the characteristics of cardiac morphology and function shown by echocardiography, the patients were divided into common type, dilated type, restricted type and reduced ejection fraction type. The clinical data of the patients were recorded, and 8 sarcomere pathogenic genes were screened by full exon sequencing or panel sequencing. Patienst were followed up and cardiovascular endpoint events were recorded. Results: A total of 815 patients with non-obstructive HCM were enrolled, including 27 (3.3%) restricted type, 51 (6.3%) dilated type, 30 (3.7%) reduced ejection fraction type and 707 (86.7%) common type. A total of 704 out of 815 patients underwent genetic testing. Among them, 299 (42.5%) patients carried at least 1 sarcomere gene mutation. MYBPC3 and MYH7 mutation accounted for 42.1% (126/299) and 35.8% (107/299) respectively. 66.7% (16/24) of the patients with restricted type carried sarcomere gene mutation, which was higher than that in patients with dilated type (36.4% (16/44)) and in common type (41.5% (250/602), P=0.015). Among the patients with reduced ejection fraction, 56.7% (17/30) patients carried sarcomere gene mutations, 23.3% (7/30) carried multiple sarcomere mutations, which was higher than that in restricted type (8.3% (2/24)), in dilated type (9.1% (4/44)) and in common type 4.2% ((24/577), P<0.001). MYH7 and MYBPC3 were the main mutation gene types of all clinical subtypes, and the genotypes were similar among groups (all P>0.05). Seven hundred and three out 815 patients were followed up for 2.9 (1.4, 4.0) years. There were 53(7.5%) cardiovascular death. Cardiovascular death occurred in 5.0% (29/578) patients with common type, 13.0% (3/23) patients with restricted type, 16.3% (7/43) patients with dilated type and 46.7% (14/30) patients with decreased ejection fraction. Univariate Cox proportional hazards model analysis showed that the risk of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type was higher than that in patients with common type (P<0.001). After adjusting for gender, age of onset, body mass index, history of hypertension, coronary heart disease and diabetes, multivariate Cox proportional hazards model analysis showed that the HR of cardiovascular death in patients with restricted, dilated and reduced ejection fraction type were 5.454 (95%CI 1.137-26.157, P=0.034) and 6.597 (95%CI 1.632-26.667, P=0.008) and 9.028 (95%CI 2.201-37.039, P=0.002) respectively, as compared to patients with common type. Conclusions: Most of the patients with non-obstructive HCM are common type, featured by mild clinical manifestations and good prognosis. Although the proportion of restricted type and dilated type is relatively low, and cardiac systolic function is mostly preserved, the clinical phenotype and prognosis of these patients are similarly severe and poor as patients with reduced ejection fraction. The genotypes are similar in different clinical subtypes, but the proportion of patients with sarcomere gene mutation is higher in restricted type, and the proportion of patients with multiple sarcomere gene mutation is higher in decreased ejection fraction type.

Screening of pathogenic genes in Chinese patients with arrhythmogenic right ventricular cardiomyopathy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable cardiac disease predominantly caused by mutations in desmosomal protein genes. Previous genetic analyses of the Chinese ARVC population are limited to small size and restriction to a single gene. This study was aimed to investigate the genotype in a large series of Chinese patients with ARVC through comprehensively screening nine ARVC-causing genes.</p><p><b>METHODS</b>A total of 100 unrelated ARVC patients and 300 age, gender and ethnicity matched healthy controls were genetically tested with multiplexing targeted resequencing for nine previously reported ARVC-causing genes, including plakophilin-2, desmoplakin, desmoglein-2, desmocollin-2, plakoglobin, transforming growth factor beta-3, transmembrane protein 43, desmin and Lamin A/C.</p><p><b>RESULTS</b>Fifty-nine mutations were identified in 64% of the patients, among which, 93% were located in desmosomal protein genes. Plakophilin-2 mutations accounted for 54% of the total and 58% of the desmosomal mutations, with a truncating mutation type making up about 2/3 of the plakophilin-2 mutations. Only four mutations were found in non-desmosomal genes; two in transmembrane protein 43 and two in transforming growth factor beta-3. Two of them (one of each gene) appeared as single missense mutations. No mutation was identified in desmin or Lamin A/C. Multiple mutations were found in 23% of the patients, with plakophilin-2 being found in 57% of the multi-mutation carriers.</p><p><b>CONCLUSIONS</b>Plakophilin-2 was the most common gene mutation that was identified in Chinese ARVC patients. Non-desmosomal genes should be added to desmosomal protein genes when performing molecular genetic screening in patients with suspected ARVC.</p>

Comparison of clinical characteristics of Chinese patients with apical hypertrophic cardiomyopathy and typical hypertrophic cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the clinical features in Chinese patients with apical hypertrophic cardiomyopathy (AHCM) and typical hypertrophic cardiomyopathy (HCM).</p><p><b>METHODS</b>This retrospective analysis included 160 patients hospitalized in Fuwai hospital. Patients were divided into three groups: apical hypertrophic cardiomyopathy (AHCM, n = 41) group, non-obstructive typical hypertrophic cardiomyopathy group [NOHCM, LVOT < 30 mm Hg (1 mm Hg = 0.133 kPa) at rest, n = 52] and obstructive typical hypertrophic cardiomyopathy (OHCM, LVOT ≥ 30 mm Hg at rest, n = 67). Clinical features, diagnosis, therapy, and plasma levels of biomarkers of these three groups were analyzed.</p><p><b>RESULTS</b>(1) The age at disease onset was older in AHCM group than in OHCM group [(49.9 ± 13.6) years vs. (41.4 ± 14.6) years, P < 0.01]. Exertional dyspnea appeared more often in HCM patients than in AHCM patients, NT-proBNP level was significantly lower in AHCM patients than in OHCM patients (P = 0.001). Plasma CK-MB, LDH, TnI and MYO levels were similar among the three groups. (2) Thirty-three AHCM patients were first hospitalized for suspected coronary heart disease (CHD) and CHD was excluded in 18 cases (43.9%). (3) The frequency of giant negative T waves (depth ≥ 10 mm) on ECG was 43.9%, 13.5% and 4.4% (P < 0.01) in AHCM, NOHCM and OHCM respectively. Half of AHCM patients showed left ventricular high voltage on ECG. (4) Cardiac magnetic resonance imaging is superior to echocardiography on correctly diagnosing AHCM.</p><p><b>CONCLUSION</b>AHCM patients differ from typical OHCM patients in clinical characteristics. There were significant differences on echocardiography and electrocardiography features among three groups. Cardiac magnetic resonance imaging and giant negative T waves on ECG are helpful for the diagnosis of AHCM.</p>

A novel hot-spot mutation S236G in the cardiac myosin binding protein C gene in Chinese patient with hypertrophic cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To identify the disease-causing gene mutations and to reveal the relationship between the genotype and the phenotype in Chinese patients with hypertrophic cardiomyopathy (HCM).</p><p><b>METHODS</b>One hundred unrelated patients with HCM and 120 controls were enrolled in this study. The full encoding exons and flanking sequences of the cardiac myosin binding protein C gene (MYBPC3) were amplified with PCR and the products were sequenced.</p><p><b>RESULTS</b>A novel missense mutation c.706T > C was identified in exon 6 of MYBPC3 gene in three HCM patients, which resulted a Serine (S) to Glycine (G) exchange at amino acid residue 236 (S236G). The clinical phenotypes of the three patients were different (2 obstructive HCM, 1 non-obstructive HCM). The 120 controls were normal in the genetic test.</p><p><b>CONCLUSIONS</b>The novel S236G mutation in MYBPC3 gene was a hot-spot mutation in Chinese patients with HCM.</p>

The genotype-phenotype correlation of MYH7 gene G15391A mutation and MYBPC3 gene G12101A mutation in familial hypertrophic cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To reveal genotype-phenotype correlation of disease-causing gene mutations in Chinese hypertrophic cardiomyopathy (HCM) pedigree.</p><p><b>METHODS</b>Peripheral 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.</p><p><b>RESULTS</b>In 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.</p><p><b>CONCLUSIONS</b>Our 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.</p>

Clinical features of dilated cardiomyopathy-like hypertrophic cardiomyopathy caused by a 13261 G > A mutation in cardiac myosin-binding protein C gene / 中华心血管病杂志

<p><b>OBJECTIVE</b>To study the disease-causing gene mutation in Chinese patients with hypertrophic cardiomyopathy (HCM) and to analyze the genotype and phenotype correlation.</p><p><b>METHODS</b>One family (n = 27) affected with HCM were chosen for the study. The full encoding exons and flanking sequences of beta-myosin heavy chain gene (MYH7) and cardiac myosin-binding protein C gene (MYBPC3) were amplified with PCR and the products were sequenced. The clinical data including symptom, physical, echocardiography and electrocardiography examinations were collected.</p><p><b>RESULTS</b>We identified a 13261 G > A mutation, which causes a missense mutation (G758D) in exon 23 of MYBPC3 in 9 family members. One mutation carrier suffered from dilated cardiomyopathy (DCM) with asymmetric interventricular septal hypertrophy (14 mm). Another mutation carrier was diagnosed as HCM.</p><p><b>CONCLUSIONS</b>The 13261 G > A mutation is associated with a DCM-like HCM and HCM phenotype in this Chinese family affected with HCM.</p>

Familiar hypertrophic cardiomyopathy caused by a IVS15-1G > A mutation in cardiac myosin-binding protein C gene / 中华心血管病杂志

<p><b>OBJECTIVE</b>To detect the disease-causing gene mutation of hypertrophic cardiomyopathy (HCM) in a Chinese family and to analyze the correlation of the genotype and the phenotype.</p><p><b>METHODS</b>One family affected with HCM was studied. The clinical data including symptom, physical examination, echocardiography and electrocardiography were collected. The full encoding exons and flanking sequences of beta-myosin heavy chain gene (MYH7) and cardiac myosin-binding protein C gene (MYBPC3) were amplified with PCR and the products were sequenced.</p><p><b>RESULTS</b>A G8887A mutation, which is an acceptor splicing site of intron 15 (IVS15-1G > A) in MYBPC3 (gi: Y10129) was identified in 6 out of 11 family members. Three mutation carriers developed HCM at 48 - 75 years old with mild chest pain, chest distress and asymmetric septal hypertrophy (13 - 14 mm) and remaining mutation carriers are free of HCM. No mutation was identified in MYH7 gene.</p><p><b>CONCLUSION</b>HCM caused by the IVS15-1G > A mutation is a benign phenotype. It is helpful to screen MYBPC3 gene mutation in late-onset HCM patients with mild symptoms.</p>

A novel LMNA gene mutation E82K associated with familial dilated cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To examine the function of the novel mutation E82K in LMNA gene identified in a Chinese family infected by dilated cardiomyopathy.</p><p><b>METHODS</b>(1) One Chinese family infected by dilated cardiomyopathy was chosen for the study. Exons 1-12 of the LMNA gene were screened with both PCR method and the cycle sequencing of the PCR products. (2) cDNA of the E82K mutation or wild type of LMNA gene was transfected into HEK293 cells and the apoptosis of the cells was detected after treatment with 0.8 mmol/L H2O2.</p><p><b>RESULTS</b>(1) A new mutation E82K in LMNA gene was identified in this dilated cardiomyopathy family. (2) Apoptosis was more in the HEK293 cells transfected with E82K mutation than those with empty vector or wild type LMNA gene.</p><p><b>CONCLUSIONS</b>The missense mutation E82K in LMNA gene changed the polar of the amino acid. It showed a malignant phenotype of severe clinical symptoms, early onset, poor survival prognosis and might be associated with atrioventricular conduction block (II degrees-III degrees), suggesting that the E82K mutation in LMNA gene may be a candidate for nosogenesis of dilated cardiomyopathy.</p>