Deafness refers to different degrees of hearing loss (HL). The factors leading to HL are complex, among which heredity is a major one. Nonsyndromic hearing loss (NSHL) accounts for 80% of hereditary deafness. More than 140 genes have been regarded to be closely related to NSHL. The mutation of GJB2 (gap junction protein, beta 2) gene accounts for 80% of NSHL and more than 50% of children NSHL, playing the most important role in deafness genes. This paper reviewed the studies on the association between GJB2 gene mutation and HL to provide reference for genetic diagnosis and counseling.
Connexin 26 ; Connexins ; genetics ; Deafness ; genetics ; Humans ; Mutation

Objective To explore the relationship between distortion product otoacoustic emission (DPOAE) test and pure tone audiometry (PTA), and the application of DPOAE test in occupational health inspection of noise-exposed work. Methods Using the judgment sampling method, 510 noise-exposed workers in an automobile engine factory were selected as the observation group. The observation group was divided into 5 subgroups according to the characteristics of PTA threshold and frequency of hearing loss. Another 50 non-noise-exposed workers in the factory were selected as the control group. DPOAE and PTA were used to detect the pure tone hearing threshold and DPOAE amplitude, signal-to-noise ratio and pass rate of each frequency in the two groups of workers. Results At 0.5-6.0 kHz, the pure tone hearing threshold value of each subgroup was higher than the control group (all P<0.05). At 3.0-6.0 kHz, the DPOAE amplitude and signal-to noise ratio of each subgroup were lower than that of the control group (all P<0.05). At 1.5 kHz, the pass rate of DPOAE in subgroup 1, subgroup 2 and subgroup 3 were higher than the control group (all P<0.05). At 2.0-6.0 kHz, the pass rate of DPOAE in subgroup 4 and subgroup 5 were lower than the control group (all P<0.05). The area receiver operating characteristic curve (AUC) of the observation subgroups and control group were 0.71-1.00 by the PTA. The AUC values of the observation subgroups and control group were 0.57-0.97 by DPOAE. The AUC value in subgroup 5 and control group had a significant difference between the two examination methods (P< 0.01); while the subgroup 1, subgroup 2, subgroup 3, subgroup 4 and control group were no significant differences respectively (all P>0.05). Conclusion DPOAE is easy to operate and can objectively reflect the hearing level of workers exposed to noise. It can be used as a supplementary means of PTA and applied to occupational health examination and hearing monitoring screening.

OBJECTIVE: To determine GJB2 allelic mutant and estimate probability of hereditary hearing loss in newborn with GJB2 heterozygous mutation in Beijing. METHOD: We performed genetic testing for sequencing of GJB2 gene for searching GJB2 allelic mutant in 915 newborn who received newborn deafness gene screening (GJB2 c. 235delC, GJB2 c. 299_300delAT, GJB2 c. 176191del16, GJB2 c. 35delG) in Beijing Tongren hospital, and the mutation were classified to pathogenic mutation,undefined variant and polymorphism. RESULT: Four hundred (43.72%, 400/915) newborn were detected to carry at least one mutation allele in GJB2. 3 (0.33%, 3/915) newborn had pathogenic mutations (c. 94C>T, c. 380G>T, c. 344T>G); 62 (6.76%, 62/915) newborn carried 14 undefined variant, 36 newborn had c. 109G>A (58.06%, 36/62),13 newborn had c. 368C>A (20.97%,13/62), six (c. 268C>G, c. 282C>T, c. 294G>C, 456C>T, c. 501G>A, c. 587T>C) are novel; 335 (36.61%, 335/915) newborn were polymorphism. CONCLUSION The probability of hereditary hearing loss is 7.09% in newborn with GJB2 heterozygous mutation in Beijing. It is noteworthy that c. 109G>A, c. 368C>A occupy a high proportion.
Alleles ; Beijing ; Connexin 26 ; Connexins ; genetics ; DNA Mutational Analysis ; Deafness ; genetics ; Genetic Testing ; Heterozygote ; Humans ; Infant, Newborn ; Mutation ; Neonatal Screening ; Polymorphism, Genetic

Objective To determine the audiological characteristics in 832 deaf children with biallelic causative mutations in GJB2 ,SLC26A4 gene .Methods The 832 patients received deafness gene screening ,553 were GJB2 gene biallelic causative mutations ,279 were SLC26A4 gene biallelic causative mutations .Patients were divided into four groups according to ages of hearing loss onset :<1 ,1~3 ,3~6 ,6~12 years old ,and the audiological character-istics and prevalence of GJB2 ,SLC26A4 gene mutations at different ages of onset .Results The prevalence of GJB2 gene mutations at four groups was 37 .97% (210/553) ,38 .34% (212/553) ,16 .27% (90/553) ,7 .41% (41/553) ,re-spectively ;the prevalence of SLC26A4 gene mutations at four groups was 25 .45% (71/279) ,44 .80% (125/279) , 20 .07% (56/279) ,9 .67% (27/279) ,respectively .The difference between GJB2 and SLC26A4 gene was significant(P=0 .001) .The prevalence of profound hearing loss with GJB2 gene mutations at four groups were 66 .67% (140/210) ,61 .32% (130/212) ,47 .78% (43/90) ,41 .46% (17/41) ,respectively .The difference was significant (P=0 .004) ,while the difference in 279 patients with SLC26A4 gene mutations was not statistically significant (P= 0 . 083) .Conclusion The age of hearing loss onset in patients with biallelic causative mutations in GJB 2 or SLC26A4 gene refers to 0~3 years -old ,hearing loss in patients with GJB2 ,SLC26A4 gene mutations gives priority to pro-found .The age of hearing loss onset is smaller ,the ratio of profound hearing loss is higher .Patients with severe and profound hearing impairment should be performed the genetic testing when the age of onset under 12 .