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>

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>

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>

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>

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>

Preliminary study on the functional localization of auditory cortex in auditory pathology patients using magnetoencephalography / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To access the pathological changes of the functional localization of the primary auditory cortex in auditory neuropathy patients using magnetoencephalography (MEG).</p><p><b>METHODS</b>The M100 waves of cortical evoked magnetic fields (AEF) evoked by 0.5, 1, 2, 4, 6, 8 kHz pure tones were measured respectively in 10 auditory neuropathy patients (20 ears) and 15 healthy young subjects (30 ears) using a whole head 306 channel magnetoencephalography (MEG) system. The auditory cortex magnetic source imaging obtained by superimposing functional MEG data on structural magnetic resonance image (MRI).</p><p><b>RESULTS</b>The M100 sources were obtained in all 15 healthy young subjects in all frequency except for 8 kHz in 16 ears. But in auditory neuropathy patients, the ratio of M100 from 0.5 to 6 kHz were 27.5% (11/40), 22.5% (9/40), 7.5% (3/40), 5% (2/40), 5% (2/40) respectively and no any waves in 8 kHz. The evoked ratio of M100 in low frequency was high and that decreased gradually with increasing of evoked pure tone frequency. The M100 latentencies and amplitudes were longer and lower in patient group than that in control group (P < 0.01).</p><p><b>CONCLUSIONS</b>Auditory neuropathy is an audiology disease with pathological lesions from the VIII cranial nerve to auditory cortex. MEG might become an important reference in decision making for therapies.</p>