Clinical Characteristics Analysis And Phenotype/genotype Correlations Of GJB2in Patients With Non-syndromic Hearing Loss

Objective1. Analyze the clinical characteristics of the patients with non-syndromichearing loss in China.2. Analyze the allele frequency of common genetic mutations in differentChinese non-syndromic hearing loss.3. Analyze the phenotype/genotype correlations of GJB2related hearing loss.4. Study the clinical characteristics of c.109G>A and c.79G>A+341A>Grelated hearing loss.Material and MethodsThe investigation took the form of a retrospective review of audiologicalevaluation findings relating to the1481cases of outpatients in our hospital inrecent4years. We obtained data of the outpatients with epidemiological methodsbased on analyzing the status of general information and audiological evaluation,analyze the positive rate of common genetic mutations in different Chinesenon-syndromic hearing loss, analyze the phenotype/genotype correlations ofGJB2related hearing loss, study the clinical characteristics of c.109G>A andc.79G>A+341A>G related hearing loss.Results1. Most of the patients with sensorineural hearing loss are bilateral symmetryprelingual（50.08%）profound sensorineural healring loss with sloping audiogram(50.1%).37.74%NSHL cases have unilateral or bilateral malformed ear.2. The allele frequency of GJB2mutations is20.57%. The most commonallele GJB2mutations are c.235delC, c.109G>A and c.299delAT. The allelefrequency of GJB2mutations is higher in patients with bilateral symmetric prelingual NSHL.3.16.18%NSHL cases are identified with the bi-allelic GJB2mutations.Most of the clinical characteristics of GJB2related NSHL are bilateral, symmetric,profound hearing loss, the audiogram is sloping in41.05%GJB2related NSHL.The hearing loss is related to onset age, and it is no progressive.4. Sequencing of GJB2showed that homozygous c.109G>A was detected in0.77%(9/1174) subjected with NSHL. The threshold is only58.61dB in NSHLwith homozygous c.109G>A mutations and it is72.32dB in NSHL withc.109G>A/other mutations. Most of the clinical characteristics of homozygousc.109G>A NSHL are similar with other GJB2mutations, except the hearing loss ismilder.5. Sequencing of GJB2showed that homozygous c.79G>A+341A>G wasdetected in5.88%subjected with NSHL. The clinical characteristics are similarwith SNP.ConclusionThe clinical characteristics of NSHL are differential. Most of the NSHL areprogressive prelingual NSHL. Only prelingual and low percentage of inner earmalformation are the clinical characteristics of bi-allelic GJB2mutations. Most ofthe clinical characteristics of homozygous c.109G>A NSHL are similar with thatof other GJB2mutations, except the hearing loss is milder. The clinicalcharacteristics of homozygous c.79G>A+341A>G are similar with SNP.