Screening And Analysis Of Genetic Susceptibility Genes In A Family With Progressive Atrioventricular Block In Hainan

Objective : Progressive atrioventricular block(Progressive cardiac conduction defect,PCCD)is a special genetic disease.Its pathogenesis is often long and progressive.The prevalence age of the disease is 30-50 years old,and it mainly affects the conduction system of the heart.The pathogenesis of PCCD is currently believed to be related to the mutation of the human body’s multiple ion channels encoding gene mutations and the abnormal expression of structural proteins.The most common genes are SCN5 A,SCN10A,SCN1 B,TRPM4,LMNA,TBX5,NKX2.5,DES,etc.Therefore,this study uses first-generation and second-generation sequencing technologies to screen candidate mutant genes and analyze the pathogenicity of a family of PCCD,aiming to find out the pathogenic genes and their mutation sites in the family for more in-depth study of PCCD.Pathogenesis.Methods:A conventional 12-lead electrocardiogram was used to screen a family of59 people in 5 generations from Hainan Province,China.The peripheral blood of patients and some healthy people in the family was collected for DNA extraction and quality inspection.After passing the test,a DNA library was established.The highthroughput sequencing system is used for sequencing,and the data obtained is screened by multiple databases to narrow the range of candidate mutation genes.The sequencing data are compared and filtered using BWA,HG19,GATK,ANNOVAR and other software and databases to screen out the incidence of PCCD Related mutated genes,and analyze their pathogenicity.The suspicious mutant genes obtained were further subjected to Sanger sequencing to verify their pathogenicity and determine the mutation site.At the same time,SIFT and Poly Phen-2 software are used to predict the protein function of candidate mutant genes and score the damage degree.Results:Through detailed consultations of the family members and analysis of their electrocardiogram and clinical manifestations,it is known that there are patients in each generation of the family members,which are in line with the characteristics of autosomal dominant inheritance.Among them,it is due to third-degree atrioventricular block.There are 5 people with pacemakers.After successfully collecting peripheral blood of family members,after whole exome sequencing,screening of multiple databases,function prediction of candidate mutant genes,and mutation bioinformatics analysis,six highly suspicious mutant genes were screened out,namely DES p.S13 F c.38C>T、RET p.A432 A c.2071G>A、DSP p.Y1512 C c.4535A>G 、 COL11A1 p.P1323L c.3968C>T、SCN5A p.A226 V c.677C>T、TRPM4 p.E330 X c.988G>T.Sanger sequencing was used to verify that the pathogenic mutant gene of this family was determined to be DES p.S13F(c.38c>T),Ser13 Phe,the 38 th base in the sequence was replaced with T,and the amino acid was changed from serine to phenylalanine.Acid,the gene coordinates are 2:220283222-220283222.At the same time,SIFT and Poly Phen-2 software were used to predict the protein function of the mutant gene.The SIFT score was-3.554;the Poly Phen-2 Hum Div score was 0.997 and the Hum Var score was 0.995.This result indicates that this mutation site is indeed a harmful site.A total of 11 members of the family were detected to carry the DES mutant gene,of which 5had the disease,and the remaining 6 had no typical clinical manifestations and electrocardiogram characteristics.Conclusions:The PCCD family members reported in this study were sequenced and found that the pathogenic mutation gene that caused their illness was a DES heterozygous missense mutation;the whole exome sequencing technology and Sanger sequencing verification can quickly identify the suspected pathogenic gene of PCCD,Has important clinical significance.Carriers of the mutant gene who have not developed the disease in this family require regular physical examinations to avoid aggravation of the disease and even sudden death,which can provide a strong basis for future genetic counseling and reproductive blockade,and also for future full exome sequencing in medical genetics.Provide a feasible way of thinking in the diagnosis and treatment of science.