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Abstract
PURPOSE OF REVIEW Hearing loss is the most common sensory deficit and in young children sensorineural hearing loss is most frequently genetic in etiology. Hearing aids and cochlear implant do not restore normal hearing. There is significant research and commercial interest in directly addressing the root cause of hearing loss through gene therapies. This article provides an overview of major barriers to cochlear gene therapy and recent advances in preclinical development of precision treatments of genetic deafness. RECENT FINDINGS Several investigators have recently described successful gene therapies in many common forms of genetic hearing loss in animal models. Elegant strategies that do not target a specific pathogenic variant, such as mini gene replacement and mutation-agnostic RNA interference (RNAi) with engineered replacement, facilitate translation of these findings to development of human therapeutics. Clinical trials for human gene therapies are in active recruitment. SUMMARY Gene therapies for hearing loss are expected to enter clinical trials in the immediate future. To provide referral for appropriate trials and counseling regarding benefits of genetic hearing loss evaluation, specialists serving children with hearing loss such as pediatricians, geneticists, genetic counselors, and otolaryngologists should be acquainted with ongoing developments in precision therapies.
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Affiliation(s)
- Miles J. Klimara
- Molecular Otolaryngology & Renal Research Laboratories, Department of Otolaryngology – Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Richard J.H. Smith
- Molecular Otolaryngology & Renal Research Laboratories, Department of Otolaryngology – Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
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Resmerita I, Cozma RS, Popescu R, Radulescu LM, Panzaru MC, Butnariu LI, Caba L, Ilie OD, Gavril EC, Gorduza EV, Rusu C. Genetics of Hearing Impairment in North-Eastern Romania-A Cost-Effective Improved Diagnosis and Literature Review. Genes (Basel) 2020; 11:genes11121506. [PMID: 33333757 PMCID: PMC7765194 DOI: 10.3390/genes11121506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/05/2020] [Accepted: 12/12/2020] [Indexed: 12/17/2022] Open
Abstract
Background: We have investigated the main genetic causes for non-syndromic hearing impairment (NSHI) in the hearing impairment individuals from the North-Eastern Romania and proposed a cost-effective diagnosis protocol. Methods: MLPA followed by Sanger Sequencing were used for all 291 patients included in this study. Results: MLPA revealed abnormal results in 141 cases (48.45%): 57 (40.5%) were c.35delG homozygous, 26 (18.44%) were c.35delG heterozygous, 14 (9.93%) were compound heterozygous and 16 (11.35%) had other types of variants. The entire coding region of GJB2 was sequenced and out of 150 patients with normal results at MLPA, 29.33% had abnormal results: variants in heterozygous state: c.71G>A (28%), c.457G>A (20%), c.269T>C (12%), c.109G>A (12%), c.100A>T (12%), c.551G>C (8%). Out of 26 patients with c.35delG in heterozygous state, 38.46% were in fact compound heterozygous. Conclusions: We identified two variants: c.109G>A and c.100A>T that have not been reported in any study from Romania. MLPA is an inexpensive, rapid and reliable technique that could be a cost-effective diagnosis method, useful for patients with hearing impairment. It can be adaptable for the mutation spectrum in every population and followed by Sanger sequencing can provide a genetic diagnosis for patients with different degrees of hearing impairment.
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Affiliation(s)
- Irina Resmerita
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
- Correspondence: or (I.R.); (R.S.C.); Tel.: +40-0741195689 (I.R.)
| | - Romica Sebastian Cozma
- Department of Otorhinolaryngology, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania;
- Correspondence: or (I.R.); (R.S.C.); Tel.: +40-0741195689 (I.R.)
| | - Roxana Popescu
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Luminita Mihaela Radulescu
- Department of Otorhinolaryngology, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania;
| | - Monica Cristina Panzaru
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Lacramioara Ionela Butnariu
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Lavinia Caba
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Ovidiu-Dumitru Ilie
- Department of Biology, Faculty of Biology, “Alexandru Ioan Cuza” University, Carol I Avenue, No 20A, 700505 Iasi, Romania;
| | - Eva-Cristiana Gavril
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Eusebiu Vlad Gorduza
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
| | - Cristina Rusu
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street, No 16, 700115 Iasi, Romania; (R.P.); (M.C.P.); (L.I.B.); (L.C.); (E.-C.G.); (E.V.G.); (C.R.)
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Wolter NE, Harrison RV, James AL. Separating the contributions of olivocochlear and middle ear muscle reflexes in modulation of distortion product otoacoustic emission levels. Audiol Neurootol 2013; 19:41-8. [PMID: 24335024 DOI: 10.1159/000356174] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 10/04/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Mediated by the medial olivocochlear system (MOCS), distortion product otoacoustic emission (DPOAE) levels are reduced by presentation of contralateral acoustic stimuli. Such acoustic signals can also evoke a middle ear muscle reflex (MEMR) that also attenuates recorded DPOAE levels. Our aim is to clearly differentiate these two inhibitory mechanisms and to analyze each separately, perhaps allowing the development of novel tests of hearing function. METHODS DPOAE were recorded in real time from chinchillas with normal auditory brainstem response thresholds and middle ear function. Amplitude reduction and its onset latency caused by contralateral presentation of intermittent narrow-band noise (NBN) were measured. Stapedius and tensor tympani muscle tendons were divided without disturbing the ossicular chain, and DPOAE testing was repeated. RESULTS Peak reduction of (2f1 - f2) DPOAE levels occurred when the center frequency of contralateral NBN approximated the primary tone f2, indicating an f2-frequency-specific response. For a 4.5-kHz centered NBN, DPOAE (f2 = 4.4 kHz) inhibition was 0.1 dB (p < 0.001). This response remained present after tendon division, consistent with an MOCS origin. Low-frequency NBN (center frequency: 0.5 kHz) reduced otoacoustic emission levels (0.1 dB, p < 0.001) across a wide range of DPOAE frequencies. This low-frequency response was abolished by division of the middle ear muscle tendons, clearly indicating MEMR involvement. CONCLUSIONS Following middle ear muscle tendon division, DPOAE inhibition by contralateral stimuli approximating the primary tone f2 persists, whereas responses evoked by lower contralateral frequencies are abolished. This distinguishes the different roles of the MOCS (f2 frequency specific) and MEMR (low frequency only) in contralateral modulation of DPOAE. This analysis helps clarify the pathways involved in an objective test that might have clinical benefit in the testing of neonates.
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Affiliation(s)
- Nikolaus E Wolter
- Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Ont., Canada
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