Research On Family Genetics Analysis Of 6 Children With Waardenburg Syndrome And The Rehabilitation Effect After Cochlear Implantation

BackgroundWaardenburg syndrome(WS)is a rare hereditary deafness,and also known as hearing and pigment abnormality syndrome.The main clinical manifestations are sensorineural hearing loss,heterochromia iridis,and prefrontal or early gray hair.The main mode of inheritance is autosomal dominant inheritance with incomplete penetrance,which has a high degree of clinical and genetic heterogeneity,making clinical diagnosis difficult.Genetic analysis of WS patients and their families is significant to further clarify its molecular etiology.For severe or extremely severe sensorineural deafness,cochlear implantation(CI)is an effective and important treatment mean,however,there are few studies on the effects of hearing and speech rehabilitation and the regularity of rehabilitation time after cochlear implantation for children with WS.Objective6 children with WS and their families were analyzed by gene detection technology to identify the pathogenic genes and mutation sites of the children,in order to find new pathogenic mutation sites and enrich the gene mutation spectrum of WS.To compare the effects of hearing and speech rehabilitation and the regularity of rehabilitation time between children with WS and non-syndromic deafness after cochlear implantation,and to provide bases for the hearing and speech rehabilitation in children with WS after cochlear implantation.Methods1.Clinical datas of 6 children and their family members were collected who were clinically diagnosed WS in our department from 2019 to 2021,and peripheral venous blood was collected to extract genomic DNA.Whole exome sequencing(WES)technology was used to screen pathogenic genes and suspected mutation sites in 6 children with WS.The mutation sites were interpreted according to the American College of Medical Genetics and Genomics(ACMG)guidelines.Sanger sequencing was used to verify the point mutation in family members,and quantitative real-time polymerase chain reaction(Q-PCR)was used to verify the copy number variation.2.40 prelingual deafness children who underwent cochlear implantation in our department from 2012 to 2021 were collected,including 20 cases in the experimental group(WS group)and 20 cases in the control group.The categories of auditory performance(CAP)and speech intelligibility rating(SIR)of the two groups were evaluated after cochlear implantation.Independent sample t test was used to compare the effects of hearing and speech rehabilitation(CAP and SIR)of cochlear implantation between WS and control groups.Spearman was used to analyze the correlation between the hearing and speech rehabilitation time and the effects of rehabilitation after cochlear implantation between WS and control groups.Mann-Whitney test was used to analyze the time regularity of hearing and speech rehabilitation after cochlear implantation.Results1.Three novel pathogenic variation sites were identified: In family 1,the proband was found to have a deletion insertion mutation c.328＿329delins TT(p.Ala110Phe)in the SOX10 gene(NM＿006941).In family 2,a missense mutation c.344C>T(p.Ala115Val)in the SOX10 gene(NM＿006941)was found in the proband.In family 3,the proband was found to have a frameshift mutation c.795＿811del CTGGTTTAGCAACCGCC(p.Trp266fs)in the PAX3 gene(NM＿181458).These three variation sites have not been included in Clin Var and HGMD databases,and have not been reported in the literature.They are all newly discovered variation sites in this study.According to ACMG guidelines,all variation sites are pathogenic.2.One novel copy number variation was identified: In family 4,Exon2-7 deletion of PAX3 gene(NM＿181458)was found in the proband,and the mutation type was copy number variation.The Q-PCR results showed that the variation of the proband was inherited from the father.According to ACMG guidelines,this variation is pathogenic.3.In family 5,a splicing mutation c.429-1G>A in the SOX10 gene(NM＿006941)was found in the proband.Sanger sequencing confirmed that neither of the parents of the proband carried the mutation site,and the proband had a de novo mutation.In Family 6,the proband was found to have a missense mutation c.142G>C(p.Gly48Arg)in the PAX3 gene(NM＿181458),which was inherited from her mother.According to the ACMG guidelines,both variation sites are pathogenic.4.There were 20 children in the WS group,including 14 boys and 6 girls,of whom 12 underwent unilateral CI and 8 underwent bilateral CI.There were 20 children in the control group,including 14 boys and 6 girls.Among them,12 cases underwent unilateral CI and 8 cases underwent bilateral CI.There was no significant difference in hearing and speech rehabilitation(CAP and SIR scores)after cochlear implantation between WS and control groups(P>0.05).There was significant difference in the correlation between the hearing and speech rehabilitation time and the effects of rehabilitation(CAP and SIR scores)between WS and control groups after cochlear implantation(P<0.001),and there was a positive correlation between the hearing and speech rehabilitation time and the effects of rehabilitation(CAP and SIR scores)after CI(R=0.943,R=0.887;R=0.822,R=0.755).The children were divided into five groups according to the hearing and speech rehabilitation time after CI.There was significant difference in CAP and SIR scores between 4 years ～ and groups within 4 years(P<0.05),but there was no significant difference in CAP and SIR scores between groups over 5 years(P>0.05).The effects of postoperative hearing and speech rehabilitation are improved with the increase of rehabilitation time,and reach a plateau at 4 years after postoperative rehabilitation.Conclusions1.WS can be diagnosed at the molecular genetic level by whole exome sequencing.In this study,3WS1 cases were caused by PAX3 gene,and 3 WS2 cases were caused by SOX10 gene.Three novel pathogenic variation sites and one novel copy number variation are identified,which enriches the gene mutation spectrum of WS.2.The effect of hearing and speech rehabilitation after CI in the WS group is similar to that in the control group.There was a positive correlation between the hearing and speech rehabilitation time and the effects of rehabilitation in the WS group after CI.The effects of hearing and speech rehabilitation are improved with the extension of rehabilitation time,and reach a plateau at 4 years after postoperative rehabilitation,which provides bases for the hearing and speech rehabilitation time of children with WS after cochlear implantation.