2001 Fiscal Year Final Research Report Summary
The screening test and gene diagnosis of myosin VIIA mutation in non-syndromic hearing loss patients
| Project/Area Number |
12671652
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
OKAMURA Hirooki Tokyo Medical and Dental University, Department of Audio-vestivular Neuroscience, Assistant Professor, 大学院・医歯学総合研究科, 助手 (50244372)
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| Co-Investigator(Kenkyū-buntansha) |
TSUTSUMI Takeshi Tokyo Medical and Dental University, Department of Audio-vestivular Neuroscience, Assistant Professor, 大学院・医歯学総合研究科, 助手 (90302851)
KITAMURA Ken Tokyo Medical and Dental University, Department of Audio-vestivular Neuroscience, Director, 大学院・医歯学総合研究科, 教授 (90010470)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Deafness gene / Molecular motors / Sensorineural hearing loss |
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| Research Abstract |
We examined the screening test and gene diagnosis of myosin VIIA mutation, which is known as actin-based molecular motors, in patients showing non- syndromic hereditary hearing loss or sensorineural hearing loss of unknown etiology. From the 81 families, 114 patients, mitochondrial DNA 3243 mutation was found 2 families 2 patients, and mitochondrial DNA 1555 mutation was 1 family 1 patient. However, the patients showing myosin VIIA mutation was not found. On the other hand, families of DFNA 11 which is known to show a myosin VIIA mutaion were examined hearing and vestibular function. Every patients of these families showed the bilateral sensorineural hearing loss in pure-tone audiogram. These patterns were flat plots or gently sloping audiograms showing progressive hearing impairment ranged from 0.2 to 2.1 dB/year in pure-tone average (PTA). No subject had detectable EOAE or DPOAE. Maximum speech discrimination scores were good in patients with PTA below 50 dB, while below 70% in patients with PTA beyond 60dB. Contralateral acoustic thresholds measurements demonstrated the positive recruitment phenomena. ABR tests revealed prolonged wave I or V in half number of the patients. These results may indicate that hearing loss of this mutation was caused by cochlear involvement, specially dysfunction of outer hair cells. In vestibular examination, half number of the patients showed bilateral caloric hyporeflexia, but did not show spontaneous nystagmus, though all of the patients have never complained vertigo.
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