OBJECTIVETo screen for mutations of deafness-related genes among ethic Chinese women of child-bearing age.

METHODSIn 324 women, 9 mutational sites in 4 deafness-related genes (SLC26A4, GJB3, GJB2 and mtDNA 12s rRNA) were screened using a gene chip.

RESULTSTwenty women (6.17%) have carried mutations. These included 11 (3.40%) carrying a GJB2 gene mutation, 7 (2.16%) carrying a SLC26A4 gene mutation, 1 (0.31%) simultaneously carrying GJB3 and GJB2 gene mutations, and 1 (0.31%) carrying a mtDNA 12s rRNA gene mutation.

CONCLUSIONWomen of child-bearing age have a high rate for carrying mutations of common deafness-related genes, among which 235delC in GJB2 was most common. Prenatal screening of couples with normal hearing is an effective way to prevent birth of affected children.

Adult ; Connexin 26 ; Connexins ; genetics ; Deafness ; genetics ; Female ; Humans ; Mutation

BACKGROUNDMutations in GJB2 gene are a major cause of autosomal recessive congenital hearing loss and the cause in some rare cases of the autosomal dominant form. The purpose of this study was to investigate the frequency and the features of GJB2 mutations in the Chinese patients with congenital sensorineural deafness.

METHODSUsing PCR amplifying the entire coding region of GJB2 gene and direct DNA sequencing to analyze mutations in this gene among unrelated 69 cases with autosomal recessive congenital nonsyndromic deafness and 27 cases of dominant congenital deafness and 35 sporadic cases. We also detected mutations in GJB2 in 100 control subjects with normal hearing.

RESULTS17.4% (12/69) of the probands in the autosomal recessive, 7.4% (2/27) of dominant families and 5.7% (2/35) of the sporadic congenital deafness patients had deafness-causing mutations in GJB2, respectively. Nine types of the mutations in GJB2 were detected in the recessive and sporadic group. They consisted of five types of polymorphism, and four types of deafness-causing mutation with homozygous 35delG in 1 sporadic (1/35), and 235delC frameshift mutation in 1 sporadic (homozygotes) and 10 recessive patients (2 heterozygotes and 8 homozygotes), and homozygous 442G-->A missense mutation and homozygous 465T-->A nonsense mutation in 1 different recessive proband, respectively. The 465T-->A that related to recessive deafness was a novel mutation found by this study. The homozygous (10/69, 14.5%) and the heterozygous (2/69, 2.9%) GJB2 mutation in the recessive patients (12/69, 17.4%) and the homozygotes in the sporadic patient (2/35, 5.7%) all had congenital severe to profound sensorineural hearing loss. 511G-->A missense mutation and 299-300delAT frameshift mutation were found in two autosomal dominant congenital deafness families (2/27, 7.4%). The total mutation frequency of GJB2 was 12.2% (16/131) in the Chinese patients with congenital sensorineural deafness and 235delC was the most common deafness-causing mutation. Six types of mutation-5 types of polymorphism and 1 type of heterozygous deletion (235delC) mutation were found in the 100 control subjects. The carry rate of the most frequent type of mutation 235delC was 0.5% in the controls (1/200 alleles). 109G-->A was the most frequent (15/100, 15%) and 79G-->A was the second common (8/100, 8%) polymorphism in this population.

CONCLUSIONSThe general mutation rate of GJB2 is 12.2% (16/131) and the 235delC is the most common type of deafness-causing mutation in Chinese patients with congenital hearing loss. 465T-->A nonsense mutation that is associated to autosomal recessive deafness is a novel mutation found by this screening. 511G-->A and 299-300delAT mutations contribute to autosomal dominant hearing loss. The study further supports the view that the common types of mutation in GJB2 according to different ethnic background and that the mutation prevalence in the East Asian deafness population is lower than that in the white population.

Connexin 26 ; Connexins ; genetics ; Hearing Loss, Sensorineural ; genetics ; Humans ; Mutation

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

OBJECTIVESTo review the identified deafness genes related to nonsyndromic hearing loss (NSHL) and summarize their expressions and functions in the cochlea and to introduce the current studies of molecular genetics on NSHL in China.

METHODSThe presented data are based on a review of the literature as well as the author' s experience with NSHL and communications with other researchers in China over the past 3 years.

RESULTSCurrently, 23 deafness genes related to NSHL have been cloned and identified. Some genes are associated with both NSHL and syndromic hearing loss (SHL), in both dominant and recessive deafness. Deafness genes have a highly specific expression pattern in the inner ear. Some functional categories are starting to emerge from a characterization of deafness genes. There are interacting genes in the genetic background that influence the extent of hearing impairment. The GJB3 gene, which is associated with high-frequency hearing impairment, was cloned in a Chinese laboratory. Mutations in some genes, such as GJB2 and mitochondrial 12S rRNA, have been screened in Chinese patients with NSHL. Mapping new deafness gene loci as well as identifying new genes and their functions is an active area of study in China.

CONCLUSIONSIt is challenging for us to continue identifying new deafness genes and analyze gene functions. By identifying genes responsible for monogenic hearing impairment, more insight may be gained into the molecular process of hearing and the pathology of hearing loss.

Chromosome Mapping ; Cloning, Molecular ; Connexin 26 ; Connexin 30 ; Connexins ; genetics ; Deafness ; genetics ; Humans ; Mutation

Objective:To elucidate the correlation between the GJB2 gene and auditory neuropathy, aiming to provide valuable insights for genetic counseling of affected individuals and their families. Methods:The general information, audiological data（including pure tone audiometry, distorted otoacoustic emission, auditory brainstem response, electrocochlography）, imaging data and genetic test data of 117 auditory neuropathy patients, and the patients with GJB2 gene mutation were screened out for the correlation analysis of auditory neuropathy. Results:Total of 16 patients were found to have GJB2 gene mutations, all of which were pathogenic or likely pathogenic.was Among them, one patient had compound heterozygous variants GJB2[c. 427C>T][c. 358_360del], exhibiting total deafness. One was GJB2[c. 299_300delAT][c. 35_36insG]compound heterozygous variants, the audiological findings were severe hearing loss.The remaining 14 patients with GJB2 gene variants exhibited typical auditory neuropathy. Conclusion:In this study, the relationship between GJB2 gene and auditory neuropathy was preliminarily analyzed,and explained the possible pathogenic mechanism of GJB2 gene variants that may be related to auditory neuropathy.
Humans ; Connexins/genetics* ; Connexin 26/genetics* ; Hearing Loss, Central/genetics* ; Deafness/genetics* ; Mutation

BACKGROUNDThe DFNB1 locus, which contains the gap junction beta-2 (GJB2) and gap junction beta-6 (GJB6) genes, plays a key role in the nonsyndromic and sporadic hearing impairment. Mutations of DFNB1 result in autosomal recessive nonsyndromic hearing impairment (ARNSHI). Previous researches have identified mutations in GJB2 and GJB6, but single nucleotide polymorphisms (SNPs) of DFNB1 locus have not been studied. So we chose five SNPs to evaluate whether there is difference between deafness people and normal-hearing people in Han Chinese.

METHODSFive SNPs in the DFNB1 region were examined using a case-control association study between cases with sporadic hearing impairment and controls with normal hearing. The HWEsoft and SHEsis softwares were used to analyze the results.

RESULTSSingle-locus association analysis showed a positive association for three SNPs: rs9315400, rs2274084 and 235delC. When we compared the distributions of the haplotypes, we also found significant differences between cases and controls in the haplotype combination of rs2274084 and rs2274083 (chi(2) = 12.978, df = 3, global P = 0.004719).

CONCLUSIONSThe haplotypes composed of rs2274084 and rs2274083 suggested that C-C may be a risk haplotype for the sporadic hearing impairment while T-T may be protective against hearing impairment. From that point of view, we can conclude that the SNPs of DFNB1 locus also plays an important role in sporadic hearing impairment cases.

Adolescent ; Child ; Connexin 26 ; Connexin 30 ; Connexins ; genetics ; Female ; Haplotypes ; Hearing Loss ; genetics ; Humans ; Male ; Polymorphism, Single Nucleotide

OBJECTIVETo analyze the coding sequence of GJB2 gene in six pedigrees with nonsyndromic hearing loss in order to find deafness-causing mutations in the GJB2 gene, and to explore the inherent pattern of deafness-causing mutations in the GJB2 gene.

METHODSGenomic DNA was extracted from peripheral blood for the probands and their family members. Coding sequence of the GJB2 gene was amplified by polymerase chain reaction, sequence variations were determined by DNA sequencing. Amplified fragments with overlapping peaks on sequencing chromatogram were sequenced by TA cloning in order to determine whether the mutations originated from the same allele.

RESULTSMutations in the GJB2 gene were found in 4 out of the 6 pedigrees with nonsyndromic hearing loss. Four types of mutations were detected in the GJB2 gene, which were 235delC, 299-300delAT, 79G>A+341A>G, and 109G>A. Compound heterozygous polymorphisms 79G>A and 341A>G, and mutations 109G>A and 235delC had deafness-causing effects.

CONCLUSIONHeterogeneous mutations of the GJB2 gene are frequently seen in patients with nonsyndromic hearing loss. Sometimes, polymorphisms may cause deafness when they are combined. Environmental factors and other genes may contribute to hearing loss caused by the GJB2 gene mutations.

Base Sequence ; Connexin 26 ; Connexins ; genetics ; DNA Mutational Analysis ; Female ; Hearing Loss ; genetics ; Humans ; Inheritance Patterns ; genetics ; Male ; Pedigree

OBJECTIVE: To detect common pathogenic variants associated with congenital deafness among neonates from Huizhou and surrounding areas and discuss its implications. METHODS: Thirteen hot-spot mutations in four most common pathogenic genes were screened among 20 934 neonates from March 2017 to December 2019. RESULTS: In total 760 neonates were found to carry common pathogenic variants (3.63%). Sixty two neonates have carried homozygous/compound heterozygous variants or homoplasmy/heteroplasmy mutations of mtDNA (0.29%). Further analysis of five abnormal cases revealed that 3 of them have carried compound heterozygous mutations of GJB2 gene, and 2 were due to compound heterozygous variants of the CDH23 gene. CONCLUSION Genetic testing has a great clinical significance for the prevention and reduction of congenital hearing loss, but the scope needs to be updated and redefined by removing mutation sites with a very low rate, adding new significant sites, and improvement of the technical strategies.
Connexin 26 ; Connexins/genetics* ; DNA Mutational Analysis ; Deafness/genetics* ; Genetic Testing ; Hearing Loss/genetics* ; Humans ; Infant, Newborn ; Mutation ; Neonatal Screening

OBJECTIVE: To construct GJB2 gene mutations common in Chinese EGFP fusion protein vectors, and to search for better way to study the mechanism of deletion mutations in GJB2 gene. METHOD: Non-fusion protein vectors of 235delC, 299-300 del AT and 176 del 16 bp were first made by point mutation methods in vitro. Then expression part of the upper 3 mutations were amplified by PCR and the PCR products were cloned into TA cloning vector. After cutting by restriction enzymes EcoRI/BamHI, three deletion mutations were inserted into pEGFP-N1 vector. Sequencing was used to verify the validity of the fusion protein vectors. HEK293 cells were transfected with the recombinant DNA samples by the liposome complex method. RESULT: The recombined plasmids were highly expressed in HEK293 cells. Green fluorescence signals were distributed uniformly in cytoplasm. CONCLUSION GJB2 mutations common in Chinese EGFP fusion protein vectors were constructed successfully. It may provide a better way to explore the reasons of nonsyndromic hearing loss common in Chinese.
Asian Continental Ancestry Group ; genetics ; Connexin 26 ; Connexins ; genetics ; Genetic Vectors ; Green Fluorescent Proteins ; genetics ; Humans ; Sequence Deletion

OBJECTIVE: To study mutations in the GJB2 gene in Kazak patients with nonsyndromic hearing impairment from Xinjiang. METHOD: One hundred and ninety-three cases of Kazak from the Xinjiang region, including 97 cases of hearing loss and 96 cases of normal people, were performed mutational analysis of the GJB2 coding region by PCR-direct sequencing. RESULT: Eight kinds of mutation were found in the encoding region of hearing impairment group:12 cases of 35 delG homozygous, 5 cases of 79G>A homozygous, 8 cases of 79G>A heterozygous, 1 case of 79G>A heterozygous and 608T>C heterozygous, 5 cases of 79G>A heterozygous and 341A>G heterozygous, 4 cases of 235 delC heterozygous, 2 cases of 341A>G heterozygous, 1 case of 439T>G heterozygous, 1 cases of 457G> A heterozygous, 2 cases of 521G>A homozygous. Four kinds of mutations found in the normal group were confirmed as common polymorphic mutation. CONCLUSION The study suggests that the GJB2 gene mutation of the Kazak deaf population in Xinjiang has ethnic and regional characteristics. There is a rather high carrier frequency of GJB2 mutation of Kazak patients in Xinjiang. In this study the 35 delG mutation is a common mutation of Kazak patients.
Adolescent ; Adult ; Child ; Child, Preschool ; China ; Connexin 26 ; Connexins ; genetics ; Deafness ; genetics ; Ethnic Groups ; genetics ; Humans ; Infant ; Mutation ; Young Adult