Genetic and phenotypic analysis of MYO15A rare variants associated with autosomal recessive hearing loss / 临床耳鼻咽喉头颈外科杂志

Objective:To analyze the phenotype and genotype characteristics of autosomal recessive hearing loss caused by MYO15A gene variants, and to provide genetic diagnosis and genetic counseling for patients and their families. Methods:Identification of MYO15A gene variants by next generation sequencing in two sporadic cases of hearing loss at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The sequence variants were verified by Sanger sequencing.The pathogenicity of these variants was determined according to the American College of Medical Genetics and Genomics（ACMG） variant classification guidelines, in conjuction with clinical data. Results:The probands of the two families have bilateral,severe or complete hearing loss.Four variants of MYO15A were identified, including one pathogenic variant that has been reported, two likely pathogenic variants,and one splicing variant of uncertain significance. Patient I carries c. 3524dupA（p. Ser1176Valfs*14）, a reported pathogenic variant, and a splicing variant c. 10082+3G>A of uncertain significance according to the ACMG guidelines. Patient I was treated with bilateral hearing aids with satisfactory effect, demonstrated average hearing thresholds of 37.5 dB in the right ear and 33.75 dB in the left ear. Patient Ⅱ carries c. 7441_7442del（p. Leu2481Glufs*86） and c. 10250_10252del（p. Ser3417del）,a pair of as likely pathogenic variants according to the ACMG guidelines. Patient Ⅱ, who underwent right cochlear implantation eight years ago, achieved scores of 9 on the Categorical Auditory Performance-Ⅱ（CAP-Ⅱ） and 5 on the Speech Intelligibility Rating（SIR）. Conclusion:This study's discovery of the rare c. 7441_7442del variant and the splicing variant c. 10082+3G>A in the MYO15A gene is closely associated with autosomal recessive hearing loss, expanding the MYO15A variant spectrum. Additionally, the pathogenicity assessment of the splicing variant facilitates classification of splicing variations.

Deafness Gene Mutations in Ningbo: 1781 Newborns Study / 中国康复理论与实践

Objective:To analyze the mutation types and frequency of deafness genes in Ningbo newborns. Methods:From January to September, 2019, 1781 newborns in Ningbo Women and Children's Hospital accepted deafness gene screening, including 22 mutations of four common deafness genes. Results:There were 104 newborns who were found deafness gene mutation (5.84%), 59 boys and 45 girls. Mutation rate was 3. 31% (59/1781) for GJB2, 0.56% (10/1781) for GJB3, 0.39% (7/1781) for mtDNA, and 1.57% (28/1781) for SLC26A4. Conclusion:The mutation rate of deafness gene in newborns in Ningbo is higher than the China average level, especially the rate of GJB2. It is necessary to screen newborn deafness gene earlier.

Study the Mutation Screening of GJB3,GJB2,mtDNA,SLC26A4 Gene in Hainan Population with Non-syndromic Hearing Impairment / 现代检验医学杂志

Objective To investigate the mutation screening of the GJB3,GJB2,mtDNA 1555 A>G and SLC26A4 gene in Hainan Pronive population with non-syndromic hearing impairment.Methods PCR were performed with one pair of primer in the coding sequence of GJB3,GJB2,mtDNA 1555 A>G and SLC26A4 gene.Bidirectional sequencing of PCR products was subsequently applied in 429 patients with hearing loss.Results 55 patients gene mutation of 429 patients were found. The point mutation in mtDNA was found in 5 patients (1.1 7%).1 5 5 5 A>G mutation of mtDNA was found in 4 patients. 1494 C>T mutation of mtDNA was found in one patients.GJB2 gene mutation was found in 25 patients (5.83%).235 del C mutation of GJB2 gene was found in 9 patients.235 del C/GJB2 299 del AT mutation was found in two patients.235 del C mutation was found in 10 patients.176 del 16 mutation was found in 4 patients.SLC26A4 mutation was found in 22 patients (5.13%).IVS7-2 A>G mutation of SLC26A4 was found in 4 patients.2168 A>G mutation of SLC26A4 was found in one patient.IVS7-2 A>G mutation was found in 12 patients.2168 A>G mutation was found in 5 patients.538 C>T mutation of GJB3 gene was found in 3 patient.IVS7-2A>G mutation and 2168 A>G muation of SLC26A4 gene was found in 4 of 22 EVA patients.Conclusion GJB2 gene and SLC26A4 gene have revealed responsible genes for Hainan deafness patients.

Prevalence of the 35delG mutation in the GJB2 gene in two samples of non-syndromic deaf subjects from Chile

Hearing loss is the most common inherited sensorial deficiency in humans; about 1 in 1000 children suffer from severe or profound hearing loss at birth. Mutations in the GJB2 gene are the most common cause of prelingual, non-syndromic autosomal recessive deafness in many populations; the c.35delG mutation is the most common in Caucasian populations. The frequency of the c.35delG mutation was estimated in two samples of deaf patients from Santiago, Chile. Unrelated non-syndromic sensorioneural deaf patients were examined: Group 1 consisted of 47 unrelated individuals with neurosensory deafness referred to the Chilean Cochlear Implant Program; Group 2 included 66 school children with prelingual deafness attending special education institutions for deaf people. Individuals with profound to moderate isolated neurosensory hearing loss with unknown etiology were included. The presence of the c.35delG mutation was evaluated by the allele-specific polymerase chain reaction method (PCR), and in some cases it was confirmed by direct DNA sequencing of the coding region of the GJB2 gene. Deaf relatives were present in 20.3% of the cases. We found 19.5% (22/113) patients with the c.35delG mutation, 6 of them homozygous; these rates are similar to frequencies found in other Latin American countries.

Genetic and Audiological Characteristics of a Chinese Family with Autosamal Dominant Hereditary Non-syndromic Low-frequency Sensorineural Hearing Loss / 听力学及言语疾病杂志

Objective To investigate the phenotype and genetic characteristics of a Chinese family with an autosomal-dominant inherited sensorineural hearing loss.Methods A Chinese pedigree associated with an autosomal-dominant inherited low-frequency sensorineural hearing loss (LFSNHL) was investigated.After obtaining informed consent from all study participants medical and audiological examination were used to rule out any syndromic hearing impairment.Five patients were tested with DPOAE and ABR,while two patients were tested with vestibular function and computed tomography scan of the temporal bone to exclude auditory neuropathy and other possible aural disorders.Twenty-one loci and twenty-three genes of DFNA screening had been done by using microsatellite markers and linkage analysis.Results Proband of the family had been diagnosed with low-frequency sensorineural hearing loss.A Chinese family BJ-L046 with non-syndromic autosomal dominant hearing loss was ascertained.Hearing impairment in the affected members in family BJ-L046 occured from 10 to 20 years of age and mainly affected the low frequencies,causing an upsloping audiogram.Higher frequencies were getting involved with increasing age,thus causing a flat-type audiogram.No positive result was found in twenty-one loci and twenty-three genes of DFNA screening.Conclusion A Chinese family with late-onset low-frequency sensorineural hearing loss was clinically studied.No positive result was found by linkage analysis,and twenty-one loci and twenty-three genes of DFNA were preliminary excluded.

Development of a molecular screening test for hereditary hearing loss and genetic susceptibility to aminoglycoside toxicity for Chinese population / 北京大学学报(医学版)

Objective: To develop a molecular screening test for genetic defects on hearing loss related genes has significant impacts on early identification of hereditary hearing loss and genetic susceptibility to aminoglycoside ototoxicity. Early identification of pre-lingual hearing loss is very important for patient's language development, academic achievement, and social skill. Two common mutations, the 235delC in GJB2 gene and the mutation A1555G in mitochondrial DNA, are included in the newly developed screening panel for Chinese population. Methods: A molecular genetic assay, based on fluorescent labeled multiplex PCR and automatic DNA fragment analyzing techniques, was developed to detect both mutations simultaneously. Results: This assay was able to detect both mutations from patient's samples, and pooled DNA tests, as well as suitable to detect mutation from the DNA extracted from dried blood spot and buccal swab. Conclusion: This assay could be a useful tool for newborn screening and carrier screening for the hereditary hearing loss for the Chinese population.

A Functional Study of Gap Junction in GJB2 Mutations Associated with Hereditary Hearing Loss / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: GJB2 (Connexin 26), the gene of the gap-junction proteins, was found to be the main causative gene of autosomal recessive nonsyndromic hearing loss (DFNB1). Whereas 35delG was known as the major type mutation in the western countries, 235delC was reported as the specific form of mutation in Asian population. The objective of this study is to identify how two mutations (235 delC, E114G) found in the Korean population affect the function of GJB2 using the molecular biology techniques. MATERIALS AND METHODS: 235delC and E114G types of mutations were cloned in the pcDNA3 vector. HeLa cells were transfected with these cloned vectors by the liposome complex method. 1) The expression and subcellular localization of Cx26 were determined using antibodies against amino acid sequences in the intracellular loop (IL) and N-terminal (NT) portions of Cx26. 2) To analyze functions of the GJB2, we examined the lucifer yellow dye transfer between cells with scrape-loaded technique. We used the wild-type (WT) Cx26 of normal hearing as a positive control, and mock cells as a negative control. RESULTS: The immunocytochemical analysis showed that cells transfected with E114G and WT gave characteristic punctuated patterns of reaction in the cell membrane with both antibodies. However, 235delC cells were not stained with the anti-IL antibody but only with the anti-NT antibody slightly around the nucleus regions. In the functional study of GJB2, transfer of lucifer yellow dye into contiguous cells was detected in E114G but not in 235delC. CONCLUSION: The 235delC type of mutation showed loss of their targeting activity on the cell membrane. As a result, the function of gap junction channels were severely deteriorated. With the E114G type mutation, we didn't find any difference when compared with the WT transfected cells. Above data indicate that types of GJB2 mutation are closely related to the status of hearing loss due to altered function of gap junction protein.