Study on in vitro differentiation of human adenoid-derived mesenchymal stem cells into olfactory sensory neurons / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the feasibility of isolation and culture of human adenoid-derived mesenchymal stem cells (aMSCs) in vitro, and to observe the differentiation of aMSCs into olfactory sensory neurons. Methods: Adenoid tissues surgically removed from children with adenoid hypertrophy in the Second Xiangya Hospital of Central South University from September to November of 2020 were collected. The adenoid tissues were digested and isolated by trypsin and then cultured with adhesion method. The expressions of cell surface antigens CD45, CD73 and CD90 on aMSCs of P5 generation were tested by flow cytometry, and the ability of osteogenic and adipogenic induction were used to identify cell differentiation ability. Then, aMSCs were induced into differentiation by retinoic acid (RA), sonic hedgehog (SHH), basic fibroblast growth factor (bFGF), RA+SHH, RA+bFGF, SHH+bFGF and RA+SHH+bFGF, respectively. The morphology of differentiated cells was observed under inverted microscope. The expression of β-tubulin 3, which was the specific marker of sensory neuron, the expressions of growth associated protein-43 (GAP43) and olfactory maker protein (OMP), which were the specific markers of olfactory sensory neuron, were detected by immunofluorescence antibody assay. The expression intensities were compared by Chi-square test of four-grid table data. Results: aMSCs were successively isolated and cultured from human adenoid tissues. P0 cells generation had good adhesion and proliferation performance. P2 cells were basically purified. P5 cells expressed CD73 and CD90 with the purity of 99.3% and 99.75% respectively, without CD45 expression. P5 cells had a good ability of osteogenic differentiation and adipogenic differentiation. Neuron-like morphology and expression of β-tubulin 3 were found in differentiated cells after induced by RA, SHH, or bFGF, respectively. An induction of expression of GAP43 was found in differentiated cells of bFGF+SHH group and RA+SHH+bFGF group, without expression of OMP of each group. The intensity of GAP43 expression of RA+SHH+bFGF group was stronger than that of bFGF+SHH group (χ2=17.48, P<0.005). Conclusions: aMSCs can be cultured from human adenoid tissues, with the stably passaged and good differentiation ability. As a new population of mesenchymal stem cells, aMSCs have the neuroregenerative properties and could differentiate into immature olfactory sensory neurons under the induction of RA+SHH+bFGF in vitro.

Effects of modified posterior nasal nerve neurectomy combined with accessory posterior nasal nerve neurectomy on controlling intractable allergic rhinitis / 中南大学学报(医学版)

Objective: A subset of intractable allergic rhinitis (iAR) patients experience severe symptoms which cannot be effectively controlled by standard drug therapy and/or antigen specific immunotherapy. In recent decades, endoscopy vidian neurectomy and posterior nasal nerve neurectomy (PNNN) were introduced as treatments of iAR that have shown to be highly successful at symptom management in a number of patients. But some patients experience relapse or suboptimal symptom control postoperation. To improve the effectiveness of PNNN to control iAR, a modified PNNN surgical approach (mPNNN) combined with accessory posterior nasal nerve neurectomy (aPNNN), which called as mPNNN-aPNNN was used. This study aims to compare the effects between mPNNN-aPNNN and PNNN on controlling the symptoms of iAR and evaluate the surgical effectiveness and safety of mPNNN-aPNNN. Methods: The patients with iAR experienced mPNNN-aPNNN or PNNN surgery at the department of Otolaryngology Head and Neck Surgery of the Second Xiangya Hospital, Central South University from January 2018 to December 2019 were analyzed retrospectively. The approach of PNNN, a selective resection of the posterior nasal nerve branches, was modified to the neurectomy of total branches of posterior nasal nerve at the sphenopalatine foramen, and combined the operation of aPNNN in which the accessory posterior nasal nerve at the palatine bone perpendicular plate was resect in our study. Daily Nasal Symptom Scores (DNSS), Total Rhinitis Medication Score (TRMS), and the Rhinoconjunctivitis Qualities of Life Questionnaires Scores (RQLQS) were used to evaluate the complications during the operation and after the operation at the 3rd, 6th, 12th, and 24th month postoperatively. Total Nasal Symptom Scores (TNSS) was used to assess the total effective rate and markedly effective rate of the operations. Results: A total of 140 iAR patients experienced mPNNN-aPNNN or PNNN. Those with concomitant septoplasty and/or inferior turbinate reduction, and were absent during the postoperative follow-up were excluded. The final 62 patients with mPNNN-aPNNN and 34 with PNNN were enrolled. DNSS, TNSS, TRMS, and RQLQS at the postoperation were significantly improved compared with the preoperation in all patients (all P<0.001). Compared with PNNN, the postoperative DNSS, TNSS, and TRMS of mPNNN-aPNNN were obviously improved (all P<0.001). There was a persisted relief of symptoms at the postoperation in all patients with mPNNN-aPNNN. The total effective rate and markedly effective rate at the postoperative 24th month were 100％ and 83.3％, respectively. Furthermore, the postoperative RQLQS decreased significantly (P<0.001). Only 5 sides of all patients (5/192, 2.6％) reported upper palate numbness during the first week after operation, with all recovered spontaneously in 1 month without treatment. No other postoperative complications occurred in mPNNN-aPNNN and PNNN.Conclusion: The surgery of mPNNN-aPNNN improve TNSS more significantly than PNNN. The operation of mPNNN-aPNNN is safe and effective to control iAR symptoms.

Application of supraclavicular fasciocutaneous island flap for reconstruction after removal of tumors in parotid and auricle area / 中华耳鼻咽喉头颈外科杂志

Objective: To evaluate the efficacy of supraclavicular fasciocutaneous island flap (SIF) for repairing the defect of parotid or auricle regions after tumor resection. Methods: From February 2019 to June 2021, 12 patients (11 males and 1 female, aged 54-77 years old), of whom 4 with parotid adenoid cystic carcinoma and 8 with auricular basal cell carcinoma underwent reconstruction surgery for postoperative defects in the parotid gland area and auricular area with SIF in the Department of Otorhinolaryngology Head and Neck Surgery, the Second Xiangya Hospital of Central South University and their clinical data were retrospectively analyzed. Size of the SIF, time for harvesting SIF, neck lymph node dissection and postoperative complications were recorded. Results: The flap areas were (6-9) cm × (8-13) cm, and the harvesting time for SIF ranged from 40 to 80 min, averaging 51.7 min. The donor sites were directly closed. All patients underwent ipsilateral levels Ⅰ-Ⅲ neck dissection, with 4 cases undergoing additional level Ⅳ neck dissection and 2 cases undergoing level Ⅳ-Ⅴ neck dissection. Of the 12 SIF, 10 were completely survival and 2 had flap arterial crisis with partial flap necrosis, in addition, 1 had donor site wound dehiscence. With follow-up of 10-42 months, there were no tumor recurrences in 10 patients, 1 patient was lost to follow-up at 10 months postoperatively, and 1 patient experienced local tumor recurrence at 11 months after surgery and died 15 months later. Conclusion: SIF is an easily harvested flap with good skin features matching the skin in parotid and auricle regions and less damage to donor site, and this flap has no need for microvascular anastomosis technique. SIF is feasible and effective for repairing defects in parotid and auricle area.

Clinical diagnosis and treatment of nasal sinus mucoceles with visual loss / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To review the clinical manifestations and management of nasal sinus mucoceles with visual loss.@*METHOD@#Medical records for 23 patients of paranasal sinus mucoceles with visual impairment were re viewed retrospectively during 8-year period (from 2002 to 2010). Ten mucoceles were found in the frontal or fronto-ethmoidal sinuses, 6 in the ethmoidal sinuses, 7 in the sphenoidal or spheno-ethmoidal sinuses. Because the majority of early chief complaints were problems related to vision, patients were often seen by ophthalmologists first. Poor vision was more common in patients with sphenoid or spheno-ethmoidal sinus mucoceles because of their proximity to the optic nerve. CT and MRI were important tools for diagnosing nasal sinus mucocele. The patients received endoscopic surgery to remove mucocele and to decompress the optic nerve. Steroid therapy was given postoperatively and routine examination with endoscopy were carried out during follow-up.@*RESULT@#Postoperatively, the majority of symptoms, such as exophthalmos, epiphora, diplopia and headache, disappeared in all patients. However, vision recovery was observed only in some patients. Recovery of vision depended on the timing of surgery and severity of initial visual loss. Delay in treatment can seriously compromise recovery of vision impairment. Moreover, patients without light perception before surgery had poor visual recovery even if optic nerve decompressions were performed.@*CONCLUSION@#Endoscopic surgery is effective to nasal sinus mucocele with visual loss. Because visual recovery depends on prompt diagnosis and surgical intervention, a good understanding of the disease and prompt imaging studies are important.

Expression of TMPRSS3 in the rat cochlea following kanamycin ototoxicity / 中南大学学报(医学版)

OBJECTIVE@#To establish the kanamycin-induced deafness model in SD rats, and to investigate the expression and significance of transmembrane protease, serine 3 (TMPRSS3) in the cochlea following kanamycin ototoxicity.@*METHODS@#A total of 40 male SD rats were randomly divided into 4 groups. The experimental rats received intramuscular kanamycin sulfate for 3, 7, and 14 consecutive days, and the control group were treated with normal saline for 14 days. Auditory brainstem responses (ABR) were obtained before and after the kanamycin administration. The expression of TMPRSS3 in the cochlea was identified and detected by immunohistochemistry and Western blot.@*RESULTS@#Kanamycin-induced deafness model in the SD rats was successfully established. ABR thresholds were increased and the expression of TMPRSS3 in the cochlea was reduced after the kanamycin injection (P<0.01).@*CONCLUSION@#TMPRSS3 may play an important role in normal cochlea function and involve in the process of aminoglycoside antibiotics induced deafness.

Aberrant expression pattern of a novel mutation in connexin 26 gene resulting in autosomal recessive deafness / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To report a novel deafness-causing mutation c.465T>A, p.Y155X in connexin 26 (CX26) (also called gap junction protein beta-2, GJB2), and perform functional analysis of the mutated protein p.Y155X in Hela cells to explore the underlying mechanism on deafness.</p><p><b>METHODS</b>Mutations in CX26 gene of the proband in an autosomal recessive inherited deafness family were tested by direct DNA sequencing method. Mutant p.Y155X, which was found in the deafness family, and wild type CX26 (wtCX26), were directionally subcloned into the pEGFP-N1 plasmid to construct the recombinant fusion protein expression vector of CX26 p.Y155X-EGFP and wtCX26-EGFP, followed by transfecting into HeLa cells. The expression of the mutated and wild type proteins was analyzed using Western blot analysis. The intracellular localization of proteins and the formation of gap junction-like plaques at plasma membrane were observed under confocal microscope. Gap junction coupling was tested by calcein-AM dye transfer experiment.</p><p><b>RESULTS</b>A novel nonsense mutation c.465T>A, p.Y155X in the CX26 gene was found in the autosomal recessive deafness family. The molecular weight of protein p.Y155X was smaller than that of wtCX26 in transiently expressed HeLa cells. The mutated protein failed to reach the cell surface to form gap junction plaques, and displayed cytoplasmic accumulation. Also, no calcein-AM dye was transferred from the donor cells to the recipient cells when both were transfected with CX26 p.Y155X. The wtCX26 protein localized at the cell membrane to form gap junction plaques with permeability to fluorescent dye calcein AM.</p><p><b>CONCLUSION</b>CX26 p.Y155X could not be targeted to the plasma membrane and there was no formation of gap junction channels between the adjacent cells. The mutation c.465T>A, p.Y155X in CX26 gene was responsible for the autosomal recessive hearing impairment in this family.</p>

GJB2 (connexin 26) gene mutation screen in patients with nonsydromic hearing loss in Hunan / 中南大学学报(医学版)

OBJECTIVE@#To identify the genetic characteristics in patients with nonsydromic hearing loss (NSHL) in Hunan province, to determine the prevalence and spectrum of mutations in GJB2 gene, and to explore the pathogenic mechanism.@*METHODS@#A total of 140 sporadic patients with NSHL were enrolled after clinical examination. Molecular studies were performed by amplifing the coding region of GJB2 gene, purifying the PCR products, and sequencing directly. Sequences were analysed by DNAStar software to determine GJB2 mutations in the patients. Special method was designed to confirm the unreported mutation.@*RESULTS@#We detected GJB2 mutation in 56 out of the 140 patients (40%, 56/140). Both of the 2 alleles were mutated in 29 patients and 1 allele in the other 27 patients, and the rate of allele mutation was 30.4%(85/280). Ten variations were detected, including 7 mutations and 3 polymorphisms. The deaf-causing mutations were nonsense mutation c.139G>T; frameshift mutation c.235delC and c.176-191del16; and missense mutation c.109G>A, c.344T>G, c.550C>T and c.571T>C. The unreported missense mutation was c.344T>G. The c.235delC mutation was the most prevalent mutation found in the 27 patients (19.3%, 27/140). The frequency of c.109G>A mutation was next to c.235delC found in 25 patients (17.9%, 25/140).@*CONCLUSION@#GJB2 mutation is a major cause for NSHL. The most common-spot in Chinese patients with NSHL is c.235delC. The unreported missense mutation is c.344T>G.

Expression of stathmin mRNA and protein in laryngeal squamous cell carcinoma and its clinical implication / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the expressions of stathmin gene and its coding protein in laryngeal squamous cell carcinoma, and to explore the relationship between stathmin gene and the biological behaviors of laryngeal squamous cell carcinoma for understanding the tumorigenicity and development of laryngeal squamous cell carcinoma.</p><p><b>METHODS</b>Laryngeal carcinoma tissues (studying group) in the tumors center and laryngeal normal tissues (control group) parted from 1.0 cm of the safe borderline of the tumors were took from 38 patients with laryngeal squamous cell carcinoma while they were in operation. Semiquantitative method of reverse transcriptase polymerase chain reaction (RT-PCR) was used to analyze the expression level of stathmin mRNA, and immunohistochemical staining (frozen section) was used to detect the expressions of stathmin protein, in laryngeal carcinoma tissues and laryngeal normal tissues of 38 cases, respectively.</p><p><b>RESULTS</b>mRNA of stathmin gene was all positively expressed in laryngeal carcinoma tissues and in laryngeal normal tissues of 38 cases by RT-PCR. However, stathmin mRNA was obviously overexpressed in laryngeal carcinoma tissues than that in laryngeal normal tissues (t = 9.655, P < 0.05). Immunohistochemical staining showed stathmin protein was positively expressed in laryngeal carcinoma tissues of 26 cases (26/38, 68.4%), and mild-positively expressed in laryngeal normal tissues in 13 cases (13/38, 34.2%). There was significant difference between the expression rate of stathmin protein in laryngeal carcinoma tissues and in laryngeal normal tissues (chi2 = 8.901, P < 0.05). Meanwhile, the expression level of stathmin mRNA and the positive-expressed rate of stathmin protein in laryngeal carcinoma tissues of the advanced stage patients group (III stage and IV stage) were significantly higher than these in laryngeal carcinoma tissues of I and II stage patients group (t = 6.284, chi2 = 5.810, P < 0.05), and they were also significantly higher in laryngeal carcinoma tissues of the patients group with cervical lymph node metastasis than in laryngeal carcinoma tissues of the patients group without cervical lymph node metastasis (t = 9.350, chi2 = 6.923, P < 0.05).</p><p><b>CONCLUSIONS</b>The expression levels of stathmin gene and protein were significantly higher in laryngeal squamous cell carcinoma than these in laryngeal normal tissues, the levels are also significantly higher in advanced stage patients group (III stage and IV stage) than in the early stage patients group (I and II), and they are also related to the cervical lymph node metastasis of carcinoma. Stathmin gene may play an important role in the pathogenesis and development of laryngeal carcinoma and may be related to its prognosis.</p>

Diagnosis and surgical treatment of the carotid body tumors / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To enhance the cure rate and lower the complication rate and the mortality rate through summarizing the clinical features and experiences in diagnosis and therapy of carotid body tumor (CBT).@*METHOD@#Retrospectively analyzed the clinical data of 21 cases (23 sides) of CBT from 1995-2095 occurring in our hospital.@*RESULT@#The accurate diagnosis rates hy using digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) were 100%. Seventeen cases (19 sides) accepted surgical operation with different kinds of procedures. The tumors of 8 cases were simplex isolated from the carotid artery. Both the tumour and the external carotid artery were resected in 9 cases. One case underwent resection of both the internal and external carotid artery and the tumour without carotid reconstruction. One case underwent resection of the internal, external carotid artery and the tumor with reconstruction of the internal carotid artery. No operative mortality was observed. The ventricular arrhythmia which had not been controlled pre-operation occurred in 1 case who was finally self-cured. One case had hoarseness and completely recovered in one week. and 1 case without carotid reconstruction had a frequent headache and gradually recovered in 5 months. The others had no complications.@*CONCLUSION@#OSA and MRI are the best methods for diagnosing CBT. Surgery is the first choice concerning the treatment of CBT. Accurate preoperative evaluation, correct therapeutic decision exquisite vascular surgical techniques can help to significantly decrease, even avoid the complications.

Reconstructive methods for hypopharynx and cervical esophagus / 中南大学学报(医学版)

OBJECTIVE@#To review the surgical treatment for reconstructing hypopharynx and cervical esophagus after hypopharyngo-oesophagectomy, and to evalue its efficacy.@*METHODS@#Different methods were adopted to reconstruct the hypopharynx and cervical esophagus among 25 cases, including 14 cases of carcinoma of the hypopharynx and 11 of carcinoma of hypopharynx and cervical esophagus. In accordance with the standard of the International Union Against Cancer in 1997, the 25 cases were divided into different clinic stages, among which 5 were in T(2)N(0), 2 in T(2)N(1), 4 in T(3)N(0), 3 in T(3)N(1), 7 in T(4)N(1) and 3 in T(4)N(2). Treatment protocol was as follow: Pure operation for 5 cases, re-operation after radiotherapy for 2 cases, operation plus radiotherapy for 18 cases, laryngeal conservation operation for 8, and neck dissection for 21 cases. Reconstruction was done by using free jejunal transplantation, gastric pull-up, the laryngotracheal flap, and myocutaneous flap.@*RESULTS@#After the reconstruction, 3 cases of free jejunal graft and gastric pull-up, 4 of laryngotracheal flap recovered oral fleeding within 2 weeks. No serious complications occurred. After 18 cases underwent the myocutaneous flap reconstruction, no complications occurred in 10 patients, but there were different complications in 8 cases, including pharyngocutaneous fistula (6 cases), haryngoesphageal stenosis (7 cases), and pectoralis major myocutaneous flap necrotic (1 case). The 3-year survival rate was 38.9% (7/18).@*CONCLUSION@#Reconstruction with free jejunal graft, gastric pull-up, and laryngotracheal flap constitutes is a safe and reliable method to restore the continuity of the upper digestive tract after pharyngo-laryngo-oesophagectomy. After the reconstruction with myocutaneous flap, there is high incidence of pharyngocutaneous fistula and haryngoesophageal stenosis.

Functional interaction of the C-terminal of Nogo protein with connexin 26 and the expression of Nogo's mRNA in the murine inner ear / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To screen and identify the proteins that interact with connexin 26 (CX26) and to analyze the expressions of these proteins in cochlea so as to explore the proteins that relate to the trafficking, assembly, localizing and gap junction functions of CX26.</p><p><b>METHODS</b>The whole coding region of GJB2 (CX26) gene was amplified from normal human genomic DNA by polymerase chain reaction (PCR) and then directionally subcloned into the vector pGBKT7 plasmid of the Match Maker Ga14 Two-Hybrid System 3 as a target to screen the interactive proteins of CX26 from the human fetal brain cDNA library by the yeast two hybrid technique. The false positive clones were discarded from the preys by repeated yeast two hybrid method between CX26 and everyone of the preys respectively. The DNAs of the insert of the identified positive clone were sequenced and BLAST analyzed against the GenBank. Lastly, the mRNA of the gene encoding the identified protein was analyzed in the murine inner ear by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>The insert of one positive clone contained 867 bp with the former 525 bp being coding region. The DNA sequence and the open reading frame of the insert were identical to the 525 bp before the stop codes (including the stop codes) and the 238 bp after the stop codes of RTN4 gene which encoded Nogo protein. And the 174 amino acid residues encoded by the insert were those of the C-terminal of Nogo protein: Nogo-A, Nogo-B and Nogo-C. RTN4 mRNA expressed in the murine inner ear was confirmed by RT-PCR method.</p><p><b>CONCLUSION</b>The C-terminal of Nogo protein interacts with CX26. Nogo protein expresses in the inner ear and may take part in the trafficking of CX26 or CX26 gap junction function.</p>

GJB2 (Cx26) gene mutations in Chinese patients with congenital sensorineural deafness and a report of one novel mutation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Mutations 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.</p><p><b>METHODS</b>Using 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.</p><p><b>RESULTS</b>17.4% (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.</p><p><b>CONCLUSIONS</b>The 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.</p>

Deafness genes for nonsyndromic hearing loss and current studies in China / 中华医学杂志(英文版)

<p><b>OBJECTIVES</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>Currently, 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.</p><p><b>CONCLUSIONS</b>It 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.</p>