The Study On Whole Exome Sequencing Of Deafness Gene In Pedigrees Of Non-syndromic Hearing Loss In Guangxi Region

Objective: Through the whole exome sequencing analysis of the nonsyndromic hearing loss pedigree members in Guangxi who have a recessive genetic heterozygous mutation or negative result from the gene chip detection of deafness,the rare deafness genes or mutation sites,and even novel deafness genes or mutation sites were searched.To provide more detailed data for the targeted design of deafness gene screening programs in Guangxi,improve the efficiency of deafness gene detection,and achieve the purpose of precision medicine.Methods: Analysis of medical history,audiologic examination,imaging and Fifteen genetic deafness gene chip detection were performed on deafness patients in Guangxi region coming to our hospital from May 2019 to December 2020.10 nonsyndromic hearing loss pedigrees in Guangxi that had negative gene chip detection results or carried recessive genetic heterozygous mutations were collected.Whole exome sequencing was performed on DNA samples from pedigree members,and Sanger sequencing was performed to verify the detected mutation sites in pedigree members.Results: 1.Pedigree 1,all patients had profound sensorineural hearing loss,and both parents had normal hearing.The gene chip detection of deafness in pedigree members was negative.Further whole exome sequencing showed that the parents of the pedigree carried heterozygous mutations of c.4143-1G>A and c.7396-1G>A in MYO15 A gene,respectively.The proband and his brother had compound heterozygous mutations of c.4143-1G>A/c.7396-1G>A in MYO15 A gene,according to the variant interpretation standards and guideline of the Amercian College of Medical Genetics and Genomics(ACMG),all of the above mutations were pathogenic mutations.The pathogenicity of above mutations was not reported by literature and database.2.Pedigree 2,the proband had profound sensorineural hearing loss,his brother had severe sensorineural hearing loss,and both parents had normal hearing.The gene chip detection of deafness in pedigree members was negative.Further whole exome sequencing showed that that the parents of the proband carried heterozygous mutations in the TRIOBP gene c.5185-2A>G and c.3299C>A,respectively.The proband and his brother had compound heterozygous mutations of c.5185-2A>G/c.3299C>A in TRIOBP gene.According to the variant interpretation standards and guideline of ACMG,TRIOBP genes c.5185-2A>G and c.3299C>A were pathogenic mutation and possible pathogenic mutation,respectively.The pathogenicity of above mutations was not reported by literature and database.3.Pedigree 3,all patients are profound sensorineural hearing loss,and their parents showed normal hearing in both ears.The gene chip detection of deafness in pedigree members was negative.Furyher whole exome sequencing revealed that the parents of the proband carried heterozygous mutations in the MYO15 A gene c.5638G>A and c.6733G>A,respectively.MYO15 A gene c.5638G>A/c.6733G>A compound heterozygous mutations were identified in the proband,proband’s sister and brother.According to the variant interpretation standards and guideline of ACMG,MYO15 A gene c.5638G>A and c.6733G>A were all possible pathogenic mutations.The pathogenicity of above mutations was not reported by literature and database.4.Pedigree 8/9/10,all patients with deafness are profound sensorineural deafness,and their parents showed normal hearing in both ears.The gene chip detection of deafness of the three pedigrees members were negative.Further whole exome sequencing of the members of the three pedigrees did not identify any suspicious mutation sites.5.Among the 8 pedigrees(a total of 17 hearing loss patients)with negative result from the gene chip detection of deafness,11 hearing loss patients 64.7%,11/17)were found to have hereditary hearing loss.Among the hereditary deafness patients,7 hearing loss patients(63.6%,7/11)carried novel pathogenic mutations.SLC26A4 mutations were found in 3pedigrees(6 hearing loss patients),in which 4 patients(66.7%,4/6)carried SLC26A4 gene c.919-2A>G mutation.Conclusions: 1.MYO15 A gene c.4143-1G>A,7396-1G>A,c.5638G>A and c.6733G>A were all novel pathogenic mutation sites,which was the important genetic causes of nonsyndromic hearing loss.2.TRIOBP gene was a rare deaf-causing gene,the novel pathogenic mutation sites of c.5185-2A>G and c.3299C>A in this study enriched the mutation spectrum of this gene.3.Among the non-syndromic hearing loss patients with negative result from the gene chip detection of deafness in Guangxi,there may be rare genes or mutation sites,and even novel disease-causing genes or mutation sites.