Analysis of DSG2, TTN and GATA4 gene variants in patients with Brugada syndrome from Henan / 中华医学遗传学杂志

OBJECTIVE@#To explore the correlation between DSG2, TTN and GATA4 genes and Brugada syndrome in Henan Province of China.@*METHODS@#From February 2017 to February 2019, 100 patients with Brugada syndrome and 100 healthy individuals were selected as the study and the control groups, respectively. Electrocardiogram and echocardiography were carried out, and peripheral blood samples was collected. Coding regions of DSG2, TTN and GATA4 genes were amplified by PCR and sequenced. The results were compared with standard sequences from GenBank.@*RESULTS@#Electrocardiogram showed that all patients from the study group had ventricular arrhythmia, 87 cases (87%) presented ventricular tachycardia (VT), 84 cases (84%) presented T wave inversion, and 51 cases (51%) presented Epsilon wave. Echocardiography showed that the right ventricle in the study group was enlarged with the inner diameter of the right ventricle being (40.0±13.3) mm, and the right ventricle showed various degree of abnormal systolic function. The enlargement of right atrium accounted for 64%, and the involvement of the left ventricle accounted for 27%. The right ventricular diameter and left ventricular diastolic diameter of the study group were significantly greater than those of the control group (P< 0.05). DNA sequencing showed that 60 patients carried DSG2 gene variants, among which 18 had missense variant of exon 8. Fifty patients carried TTN gene variants, including 8 in the A-band domain and 3 in the I-band domain. Twenty patients carried 3 variants of the GATA4 gene.@*CONCLUSION@#Variants of the DSG2, TTN and GATA4 genes in Henan region are correlated with the onset of Brugada syndrome.

Dynamic assembly of intercalated disc during postnatal development in the rat myocardium / 生理学报

The intercalated disc (ICD) complex of cardiomyocyte consists of fascia adherens, desmosomes and gap junctions which are mainly constructed by their transmembrane proteins: N-cadherin (N-cad), desmoglein-2 (DSG2) and connexin 43 (Cx43), respectively. The aim of this study was to observe the dynamic changes in colocalization of N-cad, DSG2 and Cx43 with each other in the rat left ventricular myocardium at 1, 7, 14, 28 and 90 day(s) after birth (P1, P7, P14, P28 and P90) using immunofluorescent staining. The results showed that, N-cad, DSG2 and Cx43 located all around the plasma membrane at the P1. These proteins accumulated to the long ends of cardiomyocytes, indicating preliminary formation of the ICD at the P7. The localization of three proteins at the ICD increased progressively, but their lateral localization showed an inverse trend from the P14 to P90. However, Cx43 still kept a certain amount of lateral localization in cardiomyocytes even at the P90 as compared with N-cad and DSG2. Quantitative colocalization of proteins was analyzed by the stereological method. Total percentage of colocalization of N-cad with DSG2 was 33.5% at the P1, and increased to 38.6% at the P7, 9.4% in ICD and 29.2% in lateral side. The total percentage of colocalization of N-cad with DSG2 increased to 65.7% at the P90, ICD colocalization increasing to 60.5% and lateral colocalization decreasing to 5.2%. Total percentage of colocalization of N-cad with Cx43 increased from 10.3% at the P1 to 37.1% at the P90, and only ICD colocalization increased, but lateral colocalization kept about 5%. The colocalization pattern of DSG2 with Cx43 was similar to that of N-cad with Cx43. Total percentage of colocalization of N-cad with DSG2 was higher than those of N-cad or DSG2 with Cx43. The above results suggest that the formation of mechanical junctions at the ICD of cardiomyocyte is prior to that of electrochemistry junctions during postnatal development. In other words, cardiomyocyte growth needs a stable mechanical environment at first.

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>