Screening Of MYH7 Gene Mutation Site In Hypertrophic Cardiomyopathy And Its Forensic Significance

[Objective]In Chinese Han population,there are few reports of mutations in the beta-myosin heavy chain(MYH7)gene of hypertrophic cardiomyopathy(HCM),which are closely related to sudden cardiac death caused by hypertrophic cardiomyopathy.At present,in forensic identification,hypertrophic cardiomyopathy mainly relies on gross specimens and pathomorphological diagnosis,lacking genetic diagnosis.The purpose of this study is to study the mutation sites of MYH7 gene in HCM of Chinese Han nationality,and to find new pathogenic mutation sites,so as to improve the accuracy of death cause identification in sudden death cases,and to provide evidence for forensic pathology and clinical diagnosis.[Methods]From January 2006 to June 2017,autopsy cases were collected from the Department of Pathology,Affiliated Hospital of Qingdao University,Qingdao Autopsy Center and Technical Department of Criminal Police Detachment of Qingdao Public Security Bureau.Eighteen cases of sudden death and hypertrophic cardiomyopathy(non-hypertensive)diagnosed by forensic pathology were selected as experimental group.In addition,20 autopsy cases of violent death were selected,and autopsy cases of cardiac hypertrophy and cardiac structural lesions were excluded as control group.Genomic DNA was extracted from formaldehyde-fixed paraffin-embedded tissues of the experimental group and the control group.Common mutation exon primers of MYH7 gene were designed according to Literature and Blast database respectively.Target exon fragments were amplified by polymerase chain reaction.The target exon was sequenced and analyzed by means of end-of-deoxygenation termination method and gene cloning method..Chromas program and NCBI,UCSC database were used to compare the sequencing results with the normal genome,identify the mutation sites,and analyze the biological information.HE staining and Masson staining were used for the diagnosis and analysis of myocardial histopathology.[Result]The MYH7 gene of 18 cases of sudden death of HCM was screened.The results showed that Thr446 Pro mutation was found in exon 14 of MYH7 gene in one case of HCM and Phe468 Leu mutation was found in exon 14 of MYH7 gene in another case of sudden death.No abnormal mutations were found in 20 violent deaths.Interspecies conservativeness analysis showed that the two amino acid residues of Thr446 and Pe468 were highly conserved among different species.The two gene mutation sites are missense mutations,which are sporadic cases and have not been reported in the literature at home and abroad.Thr446 Pro missense mutation and Phe468 Leu missense mutation are located in the spherical head of beta-MHC,which is an important functional region of myosin,suggesting that these two gene mutations are malignant mutations causing HCM..In addition,a synonymous mutation was found.[Conclusion]MYH7 gene is one of the pathogenic mutations of hypertrophic cardiomyopathy.Study the HCM pathogenic mutations,not only can improve the cause of death in cases of sudden death in forensic practice today identification accuracy,for forensic test case provides a powerful means of evidence-based medicine,also helps accumulate research materials and statistical data,service for teaching and scientific research,better understand China HCM genetic background and characteristics of sudden death patients.Genetic screening and early medical intervention can avoid the recurrence of tragedies,so as to achieve the purpose of early identification,accurate treatment and comprehensive prevention.