Sequencing And Analysis Of Gene Whole Exome In 21 Patients With Sensorineural Hearing Loss

Objective:The patients with sensorineural deafness suspected to be hereditary deafness were analyzed by genome-wide exome sequencing to explore deaf-causing genes and mutation sites,and their family members were verified by generation sequencing to verify the source and pathogenicity of related mutation sites.The genetic mutation characteristics of genetic deafness patients were analyzed to provide genetic counseling for patients.Meanwhile,the genetic database of genetic deafness patients was further improved to provide theoretical basis for early diagnosis,genetic counseling and prenatal screening of genetic deafness patients.Methods:From September 2020 to December 2022,patients with deafness in the outpatient department of our hospital were collected for medical history,audiology and imaging examinations,and patients suspected to be hereditary deafness were screened out.After signing the informed consent form,5m L peripheral venous blood was extracted to extract genomic DNA of human whole blood,and the whole exon was detected.The sequencing data was analyzed by biological information analysis software.The pathogenicity of detected mutations was interpreted according to the standard guidelines of the American Society of Medical Genetics and Genomics.Based on the analysis results,Sanger sequencing was performed on the related sites of the proband and its family members to verify the source and pathogenicity of the related mutation sites.Results:1.A total of 21 patients with sensorineural deafness were detected,including 8 males and 13 females.The male-to-female ratio was 0.615:1.A total of 42 ears were detected,including 6 ears with mild hearing loss(14.29%),11 ears with moderate hearing loss(26.19%),11 ears with moderate and severe hearing loss(26.19%),5 ears with severe hearing loss(11.90%),2 ears with extremely severe hearing loss(4.76%),and 7 ears with complete hearing loss/total deafness(16.66%).2.Whole exome sequencing and common gene mutation analysis were performed in21 patients.No suspected pathogenic mutation sites were detected in 2 patients,and the gene mutation carrying rate was 90.48%(19/21).3.A total of 21 mutated genes were detected in 21 patients,including 20deafness-related genes(hotspot mutated genes were SLC26A4,OTOF,MYH14,MYO7 A and GJB4 genes).A non-deafness-related gene(GLB1 gene).4.A total of 36 gene mutation sites were detected in 21 patients.Among the 35deafness-related gene mutation sites,the detection rate of c.919-2A>G mutation in SLC26A4 gene was the highest(11.43%(4/35).1 non-deaf-related gene mutation site.There were 7 pathogenic mutations(19.44%(7/36);There were 8 possible pathogenic mutations(22.22%(8/36);There were 21 mutations with unclear clinical significance,accounting for 58.33%(21/36).Conclusion:In this study,the whole exome liquid phase capture technology was used to efficiently enrich the DNA of human whole exon region,and then high-throughput and high-depth sequencing was conducted.The detection rate was high,which is an effective method to identify hereditary deafness.OTOF c.5197G>A(p.Glu1733Lys)in patient 11,OTOFc.5816G>A(p.Arg1939Gln)in patient 12,SLC26A4 c.919-2A>G in patient 14-17,SLC26A4 c.1746 del G(p.Ala584Argfs*2)and c.563T>C(p.Ile188Thr)in patient 17,USH2 Ac.13010C>T(p.Thr4337Met)in patient 18 and OPA1 c.1334G>A(p.Arg445His)in patient 19 were definite pathogenic mutations.The complex heterozygous mutation of c.5816G>A and c.1366G>T of OTOF gene was the cause of temperature sensitive hearing neuropathy in patients with 16.The complex heterozygous mutation consisting of c.13010C>T and c.11232-2A>G of USH2 A gene is the cause of usher2 A syndrome in patients with 22 usheres.The complex heterozygous mutation of OPA1 gene c.1334G>A and CDH23 gene c.4249C>T was the cause of 23 induced auditory neuropathy with optic atrophy.Patient 21 carried three SLC26A4 mutations(c.919-2A>G,c.1746 del G,c.563T>C),all of which were clear recessive disease mutation sites associated with hearing impairment.Therefore,the above three mutations of SLC26A4 gene are presumed to cause the disease in some form of complex heterozygosity.These rare mutation sites enriched the mutant spectrum of related genes.The 8 possible pathogenic mutations and 21 genes of unclear clinical significance were only carried,which is not enough to explain the cause.However,if the spouses of such carriers also carry the pathogenic mutation of the same gene,the prevalence rate of their offspring is 25%.Pregnant carriers of recessive gene mutations or their children who have fertility needs should do prenatal genetic testing and genetic counseling.