Phenotype-genotype analysis of the autosomal recessive hereditary hearing loss caused by OTOA variations / 中华耳鼻咽喉头颈外科杂志

Objective: To analyze the phenotypic-genotypic characteristics of hereditary deafness caused by OTOA gene variations. Methods: Family histories, clinical phenotypes and gene variations of six pedigrees were analyzed, which were diagnosed with hearing loss caused by OTOA gene variations at the PLA General Hospital from September 2015 to January 2022. The sequence variations were verified by Sanger sequencing and the copy number variations were validated by multiplex ligation-dependent probe amplification (MLPA) in the family members. Results: The hearing loss phenotype caused by OTOA variations ranged from mild to moderate in the low frequencies, and from moderate to severe in the high frequencies in the probands, which came from six sporadic pedigrees, among which a proband was diagnosed as congenital deafness and five were diagnosed as postlingual deafness. One proband carried homozygous variations and five probands carried compound heterozygous variations in OTOA gene. Nine pathogenic variations (six copy number variations, two deletion variations and one missense variation) and two variations with uncertain significance in OTOA were identified in total, including six copy number variations and five single nucleotide variants, and three of the five single nucleotide variants were firstly reported [c.1265G>T(p.Gly422Val),c.1534delG(p.Ala513Leufs*11) and c.3292C>T(p.Gln1098fs*)]. Conclusions: OTOA gene variations can lead to autosomal recessive nonsyndromic hearing loss. In this study, the hearing loss caused by OTOA defects mostly presents as bilateral, symmetrical, and postlingual, and that of a few presents as congenital. The pathogenic variations of OTOA gene are mainly copy number variations followed by deletion variations and missense variations.

Analysis of COL1A1 gene variation and clinical prevention and treatment in patients with Van der Hoeve syndrome / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the clinical phenotype, treatment and prevention of Van der Hoeve syndrome, and analyze the variation characteristics of its related gene COL1A1. Methods: Hearing and sequencing data of syndromic deafness patients who had undergone genetic testing for deafness at the Chinese People's Liberation Army General Hospital since January 2008 to October 2020 were retrospectively reviewed. The variation of the COL1A1 gene and return visits to traceable patients and families were summarized, the disease progress and clinical treatment effects were analyzed, and the prevention strategies were discussed. Results: A total of 7 patients with COL1A1 gene mutation underwent clinical intervention. The mutation sites were c.1342A>T (p.Lys448*), c.124C>T (p.Gln42*), c.249insG(p.Ala84*), c.668insC(p.Gly224*), c.2829+1G>C, c.1081C>T (p.Arg361*), c.1792C>T (p.Arg598*), of which c.1081C>T and c.1792C>T had been previously reported, and the remaining 5 were novo mutations that have not been reported. All the 7 probands underwent stapes implantation and received genetic counseling and prevention guidance. Conclusions: Van der Hoeve syndrome belongs to osteogenesis imperfecta type Ⅰ. The disease has high penetrance. Timely surgical intervention for hearing loss can improve the life quality in patients. Accurate genetic counseling and preimplantation genetic diagnosis can achieve the primary prevention for the disease.

Preliminary audiological evaluation of the SoundBite bone conduction devices in adults with single-sided deafness / 中华耳鼻咽喉头颈外科杂志

Objective: The auditory deficits of single-sided deafness (SSD) can be treated with a novel intra-oral device, SoundBite, which delivers sound by applying vibratory signal to the teeth. The purpose of this study was to evaluate the efficacy and benefit of the bone conduction device for Chinese adults with SSD. Methods: Eighteen patients aged 19-66 yrs with acquired, permanent sensorineural SSD and no current treatment by any other devices for SSD, were recruited in a prospective controlled, nonrandomized, unblinded study. They were requested the continually daily wear of the new device over a 30-day free trial period. The intra-oral hearing device was placed around two maxillary teeth and was similar to a small partial denture or retainer. The audiological tests included pure tone air conduction thresholds, monosyllable word recognition score (WRS) in quiet and sentence reception thresholds in noise (via CMNmatrix test). The benefit was determined with the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Speech, Spatial and Qualities of Hearing Scale (SSQ) questionnaire. Results: The monosyllable WRS and the 50% threshold of signal-to-noise ratio (SNR50) were significantly better in all aided conditions. The head shadow effect, assessed by the SNR50 via CMNmatrix test improved an average of 2.6 dB after 30 days' wearing compared with unaided condition (P<0.001). The APHAB scores improved (P<0.05) for all subjects for the Global and Ease of Communication, Reverberation, Background Noise subscales. The SSQ scores improved (P<0.05) for all subjects for Speech, Spatial and Qualities of Hearing subscales. Conclusion: The SoundBite is a good alternative to the well-established implantable bone conduction devices in patients with SSD. An improvement in listening ability in noise and quiet as well as a decrease of the head shadow effect is validated as the expected.

Primary tumors at the cervicothoracic junction / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the diagnosis and treatment of the primary tumors at the cervicothoracic junction.</p><p><b>METHODS</b>We analyzed 17 cases of the tumors diagnosed by surgery and histopathology in Chinese PLA General Hospital from Mar. 2005 to Dec.2009. The clinical manifestations, the surgical approaches and surgical complications were analyzed retrospectively.</p><p><b>RESULTS</b>The main partial of the tumors located in left side in 9 patients and in right side in 8 patients. The operation approaches included the lateral cervical incision (1 patient), the combined cervical and thorax incision (3 patients), the supraclavicular cervical incision (6 patients), the combined cervical incision and superior mediastinotomy (7 patients). Except 3 cases in whom the tumors surrounded or sticked to vital blood vessels or nerves had experienced subtotal resection, the remained 14 cases had total ablation. The morbidity occurred in 5 patients, including subclavian artery, vertebral artery and common carotid artery rupture, recurrent laryngeal nerve trauma, brachial plexus trauma and Horner' syndrome. The histopathology included the cyst, the venous haemangioma, the nodes cell neuroma, the fibroma, the fibrosarcoma, the liposarcoma, the myofibroblastic tumor, the ectopic hamartomas thymoma, the neurofibroma, and neurinoma. All the patients were followed up from 1 to 4.5 years post-operatively, with the mean follow-up of 25.3 months. The two malignant patients were alive being free of tumor with follow-up of 3 year and 8 months, and 2 year respectively. The three cases with tumor partial resection were all alive with tumour. The remained 12 benign cases with total tumor total ablation were all alive free of tumour.</p><p><b>CONCLUSIONS</b>The histopathology of the cervicothoracic junction is diversity. But the commonest pathology is neurinoma. When the tumor is extensive, enveloping or involving the vital blood vessel and nerve, it is difficult to get total ablation, and the morbidity is very high.</p>

Prenatal genetic counseling and instruction for deaf families by genetic test / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>Analyzed the molecular pathogenesis of probands by means of genetic test and assisted the local Family Planning Institute by providing prenatal genetic counseling and instruction for deaf families who eager to have more baby.</p><p><b>METHODS</b>Total of forty-three deaf families were recruited by two institutes for family planning from Guangzhou and Weifang. Forty-two families had one deaf child with normal hearing parents. One family was that parents and their child were all deaf. Genetic testing of GJB2, SLC26A4 and mitochondrial DNA (mtDNA) 12SrRNA were firstly performed in probands and their parents, following medical history, physical examination, auditory test and CT scan of temporal bone were completed. And then the genetic information and instruction were provided to each deaf family.</p><p><b>RESULTS</b>Fifteen of these 43 families had positive results of genetic test. In fifteen families, one family was confirmed that the parents and their child all carried homozygous GJB2 mutations and the recurrence risk was 100%. Twelve families were confirmed that the probands carried homozygous/compound GJB2 or SLC26A4 mutations while their parents were GJB2 or SLC26A4 carriers, and the recurrence risk was 25%. One family was confirmed that the proband, diagnosed with enlarged vestibular aqueduct syndrome (EVAS) by CT scan, carried heterozygous SLC26A4 mutation from the mother, and the recurrence risk was still 25% based on the hereditary pattern of EVAS although another SLC26A4 mutation from the father was not found. One family was confirmed that the proband carried a heterozygous GJB2 mutation from the mother and the possibility to be GJB2 carrier for offsprings was 50%. The rest 28 families were that all probands and their parents did not carry GJB2, SLC26A4 and mtDNA 12SrRNA pathological mutation.</p><p><b>CONCLUSIONS</b>Genetic testing can provide more accurate and useful prenatal genetic counseling and instruction to deaf families. Meanwhile, it is an ideal way to develop a cooperative relationship with the institute for family planning.</p>

Sequencing analysis of whole SLC26A4 gene in severe to profound sensorineural hearing loss patients with IVS7-2A to G mutation of the gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the whole sequence of the SLC26A4 gene in moderate to profound sensorineural hearing loss (SNHL) patients with IVS7-2A to G mutation of the gene in China.</p><p><b>METHODS</b>Whole SLC26A4 gene sequence was analyzed by direct sequencing in 80 SLC26A4 gene IVS7-2A to G mutation carriers for the occurrence of a second mutation in the gene.</p><p><b>RESULTS</b>Forty-seven out of the 80 patients were found to have a second heterozygous mutation, whereas a single IVS7-2A to G mutation could be responsible for SNHL in the remaining 33 patients. Three novel mutations, 5+ 2T to A, 14-2A to G and 1825del G, were identified. The five most common mutations include H723R (20%), T410M(5%), C.1705+ 5G to A (15+ 5G to A)(5%), L676Q(5%), and N392Y (3.75%). Exon 17 harbored the most types of compound heterozygosity with the IVS7-2A to G mutation.</p><p><b>CONCLUSION</b>A Chinese specific SLC26A4 diversity was found, and comparable SLC26A4 contributing to deafness. This study suggested that if a heterozygous SLC26A4 mutation is found in a patient with deafness, other exons of the SLC26A4 gene should be analyzed. Furthermore, double heterozygosity of the SLC26A4 gene may also account for some of the disease phenotype.</p>

Sequence analysis of GJB3 in Chinese deafness population who carry one heterozygous GJB2 pathogenic mutation / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate whether GJB3 and GJB2 interaction to produce a deafness phenotype in a digenic mode of inheritance in Chinese deafness population.</p><p><b>METHODS</b>A series of 108 patients with severe or profound hearing loss carrying one heterozygous GJB2 pathogenic mutation were sequenced for GJB3 coding region, which compared with the data of control group.</p><p><b>RESULTS</b>Three GJB3 missense variants including V84I, A194T and N166S, and four GJB3 nonsense mutation were detected. N166S and A194T were considered as pathogenic which cause nonsyndromic autosomal recessive hearing loss and V84I was considered as polymorphisms in Chinese population. The two patients who carried N166S and A194T respectively in one allele also carried GJB2 235delC mutation in other allele, while the other patient who carried A194T in one allele also carried GJB2 299_300delAT mutation in other allele.</p><p><b>CONCLUSIONS</b>GJB3 and GJB2 might interact to produce deafness in a digenic mode of inheritance, but the point need to be proved in further study.</p>

Sequencing analysis of whole SLC26A4 gene related to IVS7-2A > G mutation in 1552 moderate to profound sensorineural hearing loss patients in China / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the whole sequence of SLC26A4 gene among 1552 deaf students from 21 regions of China with SLC26A4 hot spot mutation IVS7-2A > G and analyze the epidemiological state of enlarged-vestibular-aqueduct-syndrome (EVAS) related hearing loss in China.</p><p><b>METHODS</b>DNA was extracted from peripheral blood of 1552 students from deaf and dumb school of 21 regions in China. The nationality of the 1552 cases covers Han (1290 cases), Uigur (69 cases), Hui (37 cases), Mongolia (31 cases), Yi, Zhuang, Bai, Miao and other 13 nationalities (125 cases). Firstly, all subjects were analyzed for the hot spot mutation IVS7-2A > G by direct sequencing. Those carrying a single heterozygous IVS7-2A > G were given further analyzed for the probable second mutation in other exons except exon7 and exon8 of SLC26A4. One hundred and fifty cases with normal hearing were in the control group.</p><p><b>RESULTS</b>The sequencing results revealed 197 cases carrying IVS7-2A > G, of whom 83 carrying IVS7-2A > G homozygous mutation, 114 carrying IVS7-2A > G heterozygous mutation. Of the 114 cases with heterozygous IVS7-2A > G, 78 cases were found to have another mutation and 36 cases were found no other mutation in SLC26A4. Of the 1552 cases, the percentage of cases carrying homozygous IVS7-2A > G and compound heterozygous mutations was 10.37% (161/1552). Of the 78 cases with SLC26A4 compound heterozygous mutations, the mutations except IVS7-2A > G were found mainly in exon 19, 10, 17, 15, 11 + 12, 14 and 3. Twenty-one novel SLC26A4 mutations were found. In the control group, there were only 3 cases carrying heterozygous IVS7-2A > G, and no other mutation in SLC26A4 was found.</p><p><b>CONCLUSIONS</b>SLC26A4 mutations account for at least 10% of EVAS related hereditary hearing loss in China. It's of great importance to screen SLC26A4 gene for making aetiological diagnosis for deafness. The discovery of novel variants of SLC26A4 gene makes the mutational and polymorphic spectrum more plentiful in Chinese population. We also provide preliminary evidence for the hot spot areas of SLC26A4.</p>

New surgical method for contact granuloma of larynx / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>For the purpose of improving the surgical effect of contact granuloma of larynx, a new surgical method was used and its effect observed.</p><p><b>METHODS</b>Under suspension laryngoscope, a part of cartilage of vocal process of arytenoid cartilage was removed until the cartilage was covered by local soft tissue after the granuloma was excised. Among 8 patients in this group, 7 were male, 1 female. Their ages ranged from 29 to 51(median 45 years old). The courses were 1 to 9 months (median 7 months). All patients experienced 1 to 5 times operations (median 2 times).</p><p><b>RESULTS</b>Using the new operative method, all 8 patients were cured for only 1 time, without recurrence followed- up for 1.5 years.</p><p><b>CONCLUSIONS</b>The granuloma were very easily recurred after the operation. The reason might be related to the exposure and inflammation of the local vocal process cartilage. The difficult key of the operation is exposure of granuloma and cartilage of vocal process because of intratracheal anesthetic tube.</p>

Real-time Taqman probe technique system for detecting the MtDNA 1555 A > G mutation / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To establish a Real-time Taqman probe technique system to detect the mtDNA 1555A > G mutation in deaf population.</p><p><b>METHODS</b>Primers and Taqman probes for mtDNA 1555A > G mutation were designed and synthesized. The technique system for detecting mtDNA 1555A > G mutation using Real-time Taqman probes was established. Then the reliability of the technique was tested in 132 patients with severe to profound hearing loss who were detected for the mtDNA 1555A > G mutation by sequencing, Kit method and Real-time Taqman probe technique at the same time. Finally, the results by the above three ways were compared.</p><p><b>RESULTS</b>Thirty-two cases with mtDNA 1555A > G mutation were found by the technique of Real-time Taqman probe. These findings coincided with the results from sequencing and Kit method completely. Both the false positive rate and the false negative rate were zero.</p><p><b>CONCLUSIONS</b>The technique possesses the merits of accuracy, convenience, high sensitivity, high specificity and intuitionistic results, etc. Importantly, the Real-time Taqman probe technique only needs 1.5 hours to detect the 1555A > G mutation and it saves 4.5 hours for one reaction compared with the Kit method popularly used nowadays. The technique system of detecting mtDNA 1555A > G mutation is reliable. It's suitable for large-scale detecting and preventive diagnosis of mtDNA 1555A > G mutation.</p>

Etiologic analysis of severe to profound hearing loss patients from Chifeng city in Inner Mongolia / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the etiology of patients with severe to profound hearing loss and to identify the ratio of hereditary hearing loss in Chifeng area in Northern China.</p><p><b>METHODS</b>DNA were extracted from peripheral blood of 134 deaf patients from Chifeng special educational school and 100 normal hearing controls in Northern China. Audiology examinations showed that all patients had severe to profound bilateral sensorineural hearing impairment. Sequence analysis of the whole coding areas of GJB2, GJB3, GJB6, SLC26A4, mtDNA12SrRNA and mtDNAtRNASer(UCN) were performed. Individuals carrying SLC26A4 mutation were given further temporal bone CT scan.</p><p><b>RESULTS</b>The ratio of hearing loss related to genetic factors in this population was 60.45% (81/134). About 33.58% (45/134) of the patients were given accurate genetic diagnosis. GJB2 mutations were responsible for approximately 17.16% of the cases in ChiFeng area. By screening SLC26A4 followed by temporal bone CT scan, we diagnosed 20 cases of enlarged vestibular aqueduct (EVA) and/or other inner ear malformation. SLC26A4 mutations account for about 14.93% of the cases. The aminoglycoside-related mtDNA 1555A>G mutation accounted for 0.76% of the cases in Chifeng area. In addition, another 13.43% (18/134) of the cases carried heterozygous GJB2 mutation and their hearing loss may be related to GJB2. 6.72% (9/134) of the cases carried heterozygous SLC26A4 mutation who were not found EVA by temporal bone CT or not took CT examination for some reasons. However, their hearing loss may also be SLC26A4-related. About 2.24% (3/134) of the cases carried mtDNA 12SrRNA 1095 T>C which may also be an aminoglycoside-related mutation and very likely be the cause of hearing loss. GJB3 might participate in the pathomechanism of hearing loss in 1.49% (2/134) of the patients. GJB6 mutation was not detected in this population.</p><p><b>CONCLUSIONS</b>The ratio of hearing loss related to genetic factors in the sample drawing population from Chifeng was 60.45% (81 cases). GJB2 is the most common gene and SLC26A4 is the second common gene next to GJB2 that cause deafness in this area.</p>

Features of nationwide distribution and frequency of a common gap junction beta-2 gene mutation in China / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To determine the prevalence of a common GJB2 mutation in a big Chinese population of deaf children and the features of its distribution in regions all over the nation and to provide epidemiology data and expertise for genetic testing of deafness in China.</p><p><b>METHODS</b>The DNA samples of NSHI patients and normal controls were collected from different typical areas of China. The method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with ApaI was used to determine the genotype of GJB2 235 site.</p><p><b>RESULTS</b>Totally 16.3% of patients carried at least one 235 delC mutant allele. Among them, 7.8% was homozygous and 8.5% was heterozygous. The prevalence of GJB2 235delC mutation in China was evident, and the significant difference of 235delC mutation frequency was found in sub-population from different areas and different ethnic groups.</p><p><b>CONCLUSIONS</b>Based upon the result of this screening as stated, Chinese NSHI patients appear to have 235delC frequency and the number of GJB2 related deafness was estimated to be huge. The testing of GJB2 235delC mutation would play an important role in genetic diagnosis and screening in China. As high as 15% of patients could be diagnosed as GJB2 caused deafness (bi-allelic mutation) only by means of this simple, fast and economic assay. In addition, patients were negative for 235delC mutation would be candidates for further mutational analysis of GJB2 or other deafness related genes.</p>

Frequency of SLC26A4 IVS7-2A > G mutation in patients with severe to profound hearing loss from different area and ethnic group in China / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To carry out molecular epidemiology study of SLC26A4 IVS7-2 A > G mutation in large Chinese deaf population and to provide evidence for fast screening and gene diagnosis of enlarged vestibular aqueduct syndrome (EVAS).</p><p><b>METHODS</b>A total of 1979 patients with non-syndromic hearing loss(NSHL) underwent questionnaire and PCR for IVSA > G mutation detection of SLC26A4 gene.</p><p><b>RESULTS</b>All 245 patients (12.38%) with homozygotes and heterozygotes IVS7-2 A > G mutation were found among the 1979 NSHL It showed statistically significant difference among north and northeast, northwest, east and southeast, southwest and central area in China. (chi2 = 34.4899, P < 0.05). Carrier frequency of the central area (27.52%) was notably higher than southwest area (6.69%). The IVS7-2 A > G mutation was most frequently found in Han deaf groups (13.88%). Tibetan, Hui, and other western minorities were lower than Han deaf population (chi2 = 35.4456, P < 0.05).</p><p><b>CONCLUSIONS</b>A high SLC26A4 IVS7-2 A > G mutation frequency for deafness in Chinese patients was found. Detection of the pathogenic mutations was bringing the possibility to detect EVAS at an early stage. Moreover, it might help to establish diverse diagnostic strategies toward differently ethical deaf population in different region of China.</p>

Genetic counseling and instruction for deaf couples directed by genetic testing / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To analyze the molecular pathogenesis of deaf couples by means of genetic testing. To provide accurate genetic counseling and instruction for deaf couples with different etiology based upon results of genetic testing.</p><p><b>METHODS</b>Four deaf families from July 2005 to May 2006. Each subject was with moderate to profound hearing loss. Genomic and mitochondrial DNA (mtDNA) of each subject were extracted from whole blood. Genetic testing of GJB2, SLC26A4 (PDS) and mtDNA A1555G mutation were offered to each individuals.</p><p><b>RESULTS</b>The husband from family 1 didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation while his wife was confirmed to carry compound SLC26A4 mutations. The possibility of their offspring's to be SLC26A4 single mutation carrier was 100%. The couple from family 2 both didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The possibility of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded. The husband from family 3 was confirmed to carry homozygous GJB2 mutations and a single SLC26A4 mutation while his wife who was diagnosed with enlarged vestibular aqueduct syndrome (EVAS) by CT scan was proven to carry a single SLC26A4 mutation. The risk of their offspring's suffering EVAS was 50%. The husband from family 4 was mtDNA A1555G positive while his wife who was diagnosed with cochlear malformation by CT scan didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The risk of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded.</p><p><b>CONCLUSIONS</b>Genetic testing could be applied to offer the more accurate genetic counseling and instruction to deaf couples.</p>

Patients suffered from enlarged vestibular aqueduct syndrome in Chifeng deaf and dumb school detected by Pendred's syndrome gene hot spot mutation screening / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the incidence of hot spot mutation of PDS gene by genetic screening testing method in Chifeng City, Inner Mongolia. The feasibility and effectiveness of genetic screening method in finding enlarged vestibular aqueduct syndrome were confirmed by temporal bone CT scan.</p><p><b>METHODS</b>DNA were extracted from peripheral blood of 141 students of Chifeng Deaf and Dumb school. PDS IVS7-2 A-G mutation, the most common PDS mutation in Chinese population, was analyzed by direct sequencing for PDS exon 7, exon 8 with intron 7. The individuals found with homozygous or heterozygous PDS IVS7-2 A-G mutation were given further temporal CT scan, ultrasound scan of thyroid and thyroid hormone assays. The results of PDS genetic screening and temporal bone CT scan were compared with each other.</p><p><b>RESULTS</b>The sequencing results revealed twenty cases carrying PDS IVS7-2 A-G mutation, of whom nine cases were homozygous mutation and eleven cases were heterozygous mutation. Eighteen cases underwent temporal bone CT scan except two cases that left the school due to other health problem. Sixteen cases were confirmed to be enlarged vestibular aqueduct syndrome (EVAS) by CT scan and the shape and function of thyroid were clinically normal by ultrasound scan of thyroid and thyroid hormone assays, respectively.</p><p><b>CONCLUSIONS</b>The patients suffered from EVAS can be diagnosed by the screening for the PDS hot spot mutation which has unique advantage in epidemiologic study in large scale deaf population. The preliminary data of this study suggested relatively high incidence of EVAS in Chifeng area.</p>