Genetic Susceptibility Study of Chinese Sudden Sensorineural Hearing Loss Patients with Vertigo

Objective To investigate the genetic causes of sudden sensorineural hearing loss(SSNHL)patients in China.This study focused on analyzing variations of coding sequence of common genes related to deafness,revealing the molecular pathogenesis of sudden deafness from a genomics perspective,discovering molecular markers associated with the onset of deafness,and then supplying prevention to high-risk populations,classifying disease according to accurate etiology,and choosing a much more precision therapy.Methods We retrospectively analyzed the clinical characteristics of 51 patients diagnosed as SSNHL with vertigo treated in the Chinese PLA General Hospital.In this study,mutation screening of 307 nuclear genes and mitochondrial genome responsible for human or mouse deafness was performed on the 51 cases of unilateral sudden deafness patients with vertigo.Results We identified 51 cases of unilateral sudden deafness,including 2 cases of low-mid frequency hearing impairment,18 cases of mid-high frequency hearing loss,11 cases of flat-type hearing loss,and 20 cases of all frequency hearing loss.Among the 51 cases,8(15.69%)cases of GJB2 heterozygous variations,1(1.96%)case of GJB3 heterozygous variations,5(9.8%)cases of SLC26A4 heterozygous variations,2(3.92%)cases of COCH heterozygous variations,14(27.45%)cases of CDH23 heterozygous variations,14(27.45%)cases of OTOF heterozygous variations,1(1.96%)case of SLC17A8 heterozygous variations and 2(3.92%)cases of KCNE1 heterozygous variations.No mtDNA gene variations were identified.Conclusion SSNHL has some relationship with hereditary in Chinese population,but its complex genetic pathogenic mechanisms need further study.

A POU3F4 Mutation Causes Nonsyndromic Hearing Loss in a Chinese X-linked Recessive Family

Background： The molecular genetic research showed the association between X-linked bearing loss and mutations in POU3F4. This research aimed to identify a POU3F4 mutation in a nonsyndromic X-linked recessive hearing loss family. Methods： A series of clinical evaluations including medical history, otologic examinations, l：amily history, audiologic testing, and a high-resolution computed tomography scan were performed t＇or each patient. Bidirectional sequencing was carried out for all polymerase chain reaction products or＇the samples. Moreover, 834 controls with normal hearing were also tested. Results： The pedigree showed X-linkage recessive inheritance pattern, and pathogenic mutation （c.499C〉T） was identified in the proband and his family member, which led to a premature termination prior to the entire POU domains. This mutation co-segregated with bearing loss in this family. No mutation ofPOU3F4 gene was found in 834 controls. Conclusions： A nonsense mutation is identified in a family displaying the pedigree consistent with X-linked recessive pattern in POU3F4 gene. In addition, we may provide molecular diagnosis and genetic counseling for this family.

Clinical Auditory Phenotypes Associated with GATA3 Gene Mutations in Familial Hypoparathyroidism-deafness-renal Dysplasia Syndrome

Background： Hypoparathyroidism-deafness-renal dysplasia （HDR） syndrome is an autosomal dominant disorder primarily caused by haploinsufficiency of GATA binding protein 3 （GATA3） gene mutations, and hearing loss is the most frequent phenotypic feature. This study aimed at identifying the causative gene mutation for a three-generation Chinese t;amily with HDR syndrome and analyzing auditory phenotypes in all familial HDR syndrome cases. Methods： Three affected family members underwent otologic examinations, biochemistry tests, and other clinical evaluations. Targeted genes capture combining next-generation sequencing was pertbrmed within the family. Sanger sequencing was used to confirm the causative mutation. The auditory phenotypes of all reported familial H DR syndrome cases analyzed were provided. Results： In Chinese family 712 l, a heterozygous nonsense mutation c.826C〉T （p.R276＊） was identified in GA TA3. All the three affected members suffered from sensorineural deafness and hypocalcemia; however, renal dysplasia only appeared in the youngest patient. Furthermore, an overview of thirty HDR syndrome families with corresponding GATA3 mutations revealed that hearing impairment occurred earlier in the younger generation in at least nine familial cases （30%） and two thirds of them were found to carry premature stop mutations. Conclusions： This study highlights the phenotypic heterogeneity of HDR and points to a possible genetic anticipation in patients with HDR, which needs to be further investigated.