Study Of Gene Mutations In Patients With Syndromic Deafness In Guangxi

Objective(s):Through whole genome sequencing(WGS)and clinical diagnostic analysis,the pathogenic genes and genetic characteristics of patients with syndromic deafness were clarified,and the molecular genetics and clinical features of patients with syndromic deafness were analyzed,and possible molecular pathogenic mechanisms were explored.The characteristics of gene mutations in deaf patients in Guangxi were analyzed,and a theoretical basis was provided for the prevention and treatment of deafness.Method(s):1.A total of 202 cases(194 families)of congenital deafness patients in Guangxi were selected from our hospital and collected from deaf schools in Guangxi,and the family lines of deafness were collected for medical history,physical examination,specialized physical examination,audiology and imaging examination,cardiac color ultrasound,blood routine examination,etc.,and the family map was drawn to make clinical diagnosis.Among them,17 patients(14families)had abnormalities of other organs or systems.2.Blood samples from the families of deaf patients were collected,DNA was extracted,whole genome sequencing was performed on 202 deaf patients,combined with bioinformation analysis(OMIM,Clinvar,DVD and other databases),mutation harmful software prediction(SIFT,Polyphen2,Mutation Taster,Mutation Assessor,FATHMM)and the clinical phenotype of the patient,according to the ACMG guidelines,the pathogenicity of the detected mutant genes was interpreted.Deaf patients and their families with identified pathogenic genes were sequenced by Sanger sequencing for verification.3.The whole genome sequencing results of 202 cases were counted,and the gene mutation spectrum of deafness gene mutation and the gene mutation characteristics of patients with syndromic deafness in Guangxi were plotted.Result(s):Family proband 1 had very severe sensorineural hearing loss in both ears,bilateral goiter,thick eyebrows,widened eye distance,his mother had a history of binaural sensorineural hearing loss with goiter,the father had a normal phenotype,and the prospector 1 and his mother detected SLC26A4 c.919-2A>G homozygous mutation,which is a shear site variation.Sanger verified that the father carried the mutation.Combined with the above results,the proband 1 and his mother were diagnosed as Pendred syndrome;Family proband 2 had very severe sensorineural hearing loss in both ears,bright blue iris in the left eye,widened eye distance,mild sensorineural hearing loss in his left ear,normal paternal phenotype,and PAX3 c.811C>T detected by Proband 2 and his mother(p.Arg271Cys)is a heterozygous mutation and is a missense mutation.Sanger verified that the father did not have the mutation at the site.Combined with the above results,the first adoptor 2 diagnosed Waardenburg syndrome type I(WS1),and the mother was Waardenburg syndrome type II(WS2);Family 3proband 3 had extremely severe sensorineural hearing loss in both ears,bright blue iris in both eyes,freckles on the face,yellowish hair,and normal parental phenotype,and MITF c.632T>C was detected in prospect 3(p.Leu211Pro),a missense mutation,may be a new mutation.The mother failed to collect a blood sample,and Sanger verified that the father did not have the mutation at the site.Combined with the above results,the first proof 3 was diagnosed as Waardenburg syndrome type II(WS2);Family 4 proband has severe sensorineural hearing loss in both ears,blue iris of the right eye,ptosis of the left upper eyelid,bilateral vestibular enlargement,internal auditory tract enlargement,and bilateral inner ear deformity.His mother had severe sensorineural hearing loss in both ears,blue iris in the right eye,yellowish hair,and a normal paternal phenotype,and Proband 4 and his mother were detected with a heterozygous mutation of SOX10 c.1359＿1360ins GCCCCACA(p.His454Alafs),which was a frameshift mutation.Based on the above results,Prospector 4 and his mother were diagnosed with Waardenburg syndrome type II(WS2);Family 5 prospectors had binaural sensorineural hearing loss,congenital heart disease-small atrial septal defect,family 6 prospectors had binaural sensorineural hearing loss,congenital heart disease,craniofacial malformations,all without family history,both of which detected GJB2 c.109G>A(p.Val37Ile)homozygous mutation,which was more frequent in normal populations(7.05% in the normal population of East Asia in the gnom AD database),so its determination as the causative gene of this patient needs further discussion;The remaining 8 patients with deafness and other systemic abnormalities did not detect the relevant pathogenic variant gene loci.There were 48 cases of 202 cases of deafness patients who were clearly diagnosed,including 25 cases of SLC26A4 gene mutation,3 cases of GJB2 gene mutation(non-c.109G>A),3 cases of MYO15 A gene mutation,2 cases of LRTOMT,GRXCR1,EYA1,WFS1,PAX3 and SOX10 gene mutations,and 1 case each of EYA4,TRIOBP,PCDH15,USH1 C and MITF gene mutations.Conclusion(s):1.In this study,the causative causes of 4 families of rare syndromic deafness were clarified,and SLC26A4 c.919-2A>G were known common pathogenic variants,MITF c.632T>C was the second reported case in patients,PAX3 c.811C>T and SOX10 c.1359＿1360ins GCCCCACA were the first cases reported in patients.Expands the spectrum of pathogenic variants in Waardengburg syndrome.2.The results of this study showed that there was still phenotypic heterogeneity in Waardengburg syndrome caused by the same gene variant,and the only mild deafness caused by PAX3 variant was likely to be caused by WS penetrance insufficiency.Therefore,the diagnosis of syndromic deafness depends on the results of genetic testing,and attention should be paid to the use of genetic testing in clinical diagnosis.3.GJB2 c.109G>A may be the deafness gene of proband 5 and 6,but it cannot explain abnormalities in other systems,and it may be that the patient is not syndromic deafness,which needs further study.For patients who fail to detect the mutation site of the relevant pathogenic gene,there may be unknown mutant gene or unknown site of known mutant gene,which requires further in-depth study and exploration.4.In this study,the pathogenic genes of 48 deaf patients in Guangxi were clarified,the diagnosis rate was 23.76%(48/202),the common causative gene was SLC26A4,and the proportion of syndromic deafness in the deafness patients was 2.06%(4/194),of which Waardengburg syndrome accounted for 1.55%(3/194)and Pendred syndrome accounted for 0.52%(1/194).