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Jung J, Lin H, Koh YI, Ryu K, Lee JS, Rim JH, Choi HJ, Lee HJ, Kim HY, Yu S, Jin H, Lee JH, Lee MG, Namkung W, Choi JY, Gee HY. Rare KCNQ4 variants found in public databases underlie impaired channel activity that may contribute to hearing impairment. Exp Mol Med 2019; 51:1-12. [PMID: 31434872 PMCID: PMC6802650 DOI: 10.1038/s12276-019-0300-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 04/01/2019] [Accepted: 05/06/2019] [Indexed: 02/08/2023] Open
Abstract
KCNQ4 is frequently mutated in autosomal dominant non-syndromic hearing loss (NSHL), a typically late-onset, initially high-frequency loss that progresses over time (DFNA2). Most KCNQ4 mutations linked to hearing loss are clustered around the pore region of the protein and lead to loss of KCNQ4-mediated potassium currents. To understand the contribution of KCNQ4 variants to NSHL, we surveyed public databases and found 17 loss-of-function and six missense KCNQ4 variants affecting amino acids around the pore region. The missense variants have not been reported as pathogenic and are present at a low frequency (minor allele frequency < 0.0005) in the population. We examined the functional impact of these variants, which, interestingly, induced a reduction in potassium channel activity without altering expression or trafficking of the channel protein, being functionally similar to DFNA2-associated KCNQ4 mutations. Therefore, these variants may be risk factors for late-onset hearing loss, and individuals harboring any one of these variants may develop hearing loss during adulthood. Reduced channel activity could be rescued by KCNQ activators, suggesting the possibility of medical intervention. These findings indicate that KCNQ4 variants may contribute more to late-onset NSHL than expected, and therefore, genetic screening for this gene is important for the prevention and treatment of NSHL.
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Affiliation(s)
- Jinsei Jung
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Haiyue Lin
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Young Ik Koh
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Kunhi Ryu
- Yonsei University College of Pharmacy, Incheon, 21983, Korea
| | - Joon Suk Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - John Hoon Rim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Hye Ji Choi
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Hak Joon Lee
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Hye-Youn Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Seyoung Yu
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Hyunsoo Jin
- Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Ji Hyun Lee
- Department of Dermatology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 03722, Korea
| | - Min Goo Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Wan Namkung
- Yonsei University College of Pharmacy, Incheon, 21983, Korea
| | - Jae Young Choi
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea.
| | - Heon Yung Gee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Korea.
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Ouyang XM, Yan D, Yuan HJ, Pu D, Du LL, Han DY, Liu XZ. The genetic bases for non-syndromic hearing loss among Chinese. J Hum Genet 2009; 54:131-40. [PMID: 19197336 DOI: 10.1038/jhg.2009.4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Deafness is an etiologically heterogeneous trait with many known genetic, environmental causes or a combination thereof. The identification of more than 120 independent genes for deafness has provided profound new insights into the pathophysiology of hearing. However, recent findings indicate that a large proportion of both syndromic and non-syndromic forms of deafness in the Chinese population are caused by defects in a small number of genes. Studies of the genetic epidemiology and molecular genetic features revealed that there is a clear relevance of genes causing deafness in Chinese deaf patients as well as a unique spectrum of common and rare deafness gene mutations in the Chinese population. This review is focused on the genetic aspects of non-syndromic and mitochondrial deafness, in which unique molecular genetic features of hearing impairment have been identified in the Chinese population. The current China population is approximately 1.3 billion. It is estimated that 30,000 infants are born with congenital sensorineural hearing loss each year. Better understanding of the genetic causes of deafness in the Chinese population is important for accurate genetics counseling and early diagnosis for timely intervention and treatment options.
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Affiliation(s)
- Xiao Mei Ouyang
- Department of Otolaryngology, University of Miami, Miami, FL 33136, USA
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KCNQ4 mutations associated with nonsyndromic progressive sensorineural hearing loss. Curr Opin Otolaryngol Head Neck Surg 2009; 16:441-4. [PMID: 18797286 DOI: 10.1097/moo.0b013e32830f4aa3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This article provides an update on the current progress in identification of KCNQ4 mutations responsible for DFNA2, a subtype of autosomal dominant nonsyndromic progressive hearing loss. RECENT FINDINGS Hearing loss in pateints with DFNA2 usually start at high frequencies in their 20s and 30s, and then progress to more than 60 dB in less than 10 years, with middle and low frequencies often affected as well. To date, eight missense mutations and two deletions of the KCNQ4 gene have been identified in patients with DFNA2 with various clinical phenotypes. In general, missense mutations are associated with younger-onset and all-frequency hearing loss, whereas deletion mutations are underlying later-onset and pure high-frequency hearing loss. The etiology of DFNA2 remains largely unknown at this point, even though the degeneration of cochlear outer hair cells, caused by dysfunction of KCNQ4 channels, might be one of the underlying mechanisms. SUMMARY During the last decade, significant progress has been made in identifying KCNQ4 mutations in patients with DFNA2. Elucidation of the pathogenic effect of these mutations will help to gain insights into the molecular mechanisms of hearing and hearing loss, which, in turn, will facilitate informative genetic counseling, early diagnosis, and even treatment of hearing loss.
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Apps SA, Rankin WA, Kurmis AP. Connexin 26 mutations in autosomal recessive deafness disorders: a review. Int J Audiol 2007; 46:75-81. [PMID: 17365058 DOI: 10.1080/14992020600582190] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This review explores the association between GJB2 gene mutations, encoding connexin 26 (Cx26), and nonsyndromic hearing loss. Connexins are proteins that form intracellular membrane channels and regulate ion movement between contiguous fluid spaces. A family of autosomal gene mutations has been identified that lead to abnormal connexin expression within the inner ear that are associated with hearing loss. The exact mechanism by which this link is elicited remains unclear. We aim to highlight the clinically underestimated prevalence of GJB2 gene mutations, to explore the influential role of ethnic diversity in mutation frequency, and to provide a framework for hearing specialists in considering the differential diagnosis of nonsyndromic hearing loss. By linking an observed phenotype associated with abnormal Cx26 expression to the current understanding of the biological and genetic basis underlying it will allow a more accurate clinical description of associated hearing loss, and therefore enable more effective patient management and genetic counselling.
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Affiliation(s)
- Stacey A Apps
- School of Speech Pathology and Audiology, Faculty of Health Sciences, Flinders University, Adelaide, Australia
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Topsakal V, Pennings RJE, te Brinke H, Hamel B, Huygen PLM, Kremer H, Cremers CWRJ. Phenotype determination guides swift genotyping of a DFNA2/KCNQ4 family with a hot spot mutation (W276S). Otol Neurotol 2005; 26:52-8. [PMID: 15699719 DOI: 10.1097/00129492-200501000-00009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Genotype a family trait with autosomal dominant nonsyndromic sensorineural hearing impairment guided only by the phenotype. STUDY DESIGN Family study. SETTING Tertiary referral center. PATIENTS Fifteen family members. METHODS In the first phase, sequence analysis was performed on DNA isolated from buccal swabs of the proband and her daughter, guided by the phenotype based on audiometric data that were already available. After detection of the W276S missense mutation in the KCNQ4 gene in both patients, this finding was confirmed in the other affected family members. All participants completed a questionnaire, were clinically examined, and underwent standard pure-tone audiometry. The results were analyzed to refine the phenotypic features of the family trait. RESULTS All clinically affected participants were carriers of the W276S hotspot mutation in exon 5 of the KCNQ4 gene on chromosome 1p34. Refined phenotypic features confirmed previously described phenotypes of DFNA2 families. CONCLUSIONS Phenotype determination can be cost saving and very effective in detecting the genotype of autosomal dominant nonsyndromic hearing impairment, especially when phenotype analyses can be performed on data that are already available or easily collected.
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Audiometry, Pure-Tone
- Child
- Chromosome Aberrations
- Cross-Cultural Comparison
- DNA Mutational Analysis
- Disease Progression
- Female
- Follow-Up Studies
- Genes, Dominant
- Genetic Carrier Screening
- Genotype
- Hearing Loss, High-Frequency/diagnosis
- Hearing Loss, High-Frequency/genetics
- Hearing Loss, Sensorineural/diagnosis
- Hearing Loss, Sensorineural/genetics
- Humans
- KCNQ Potassium Channels
- Male
- Middle Aged
- Mutation, Missense
- Netherlands
- Pedigree
- Phenotype
- Potassium Channels, Voltage-Gated/genetics
- Presbycusis/diagnosis
- Presbycusis/genetics
- Sequence Analysis, DNA
- Statistics as Topic
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Affiliation(s)
- Vedat Topsakal
- Department of Otorhinolaryngology, Radboud University Nijmegen Medical Centre, The Netherlands
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Rozengurt N, Lopez I, Chiu CS, Kofuji P, Lester HA, Neusch C. Time course of inner ear degeneration and deafness in mice lacking the Kir4.1 potassium channel subunit. Hear Res 2003; 177:71-80. [PMID: 12618319 DOI: 10.1016/s0378-5955(02)00799-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The Kir4.1 gene (KCNJ10) encodes an inwardly rectifying K(+) channel subunit abundantly expressed in the CNS. Its expression in the mammalian inner ear has been suggested but its function in vivo in the inner ear is unknown. Because diverse human hereditary deafness syndromes are associated with mutations in K(+) channels, we examined auditory function and inner ear structure in mice with a genetically inactivated Kir4.1 K(+) channel subunit. Startle response experiments suggest that Kir4.1-/- mice are profoundly deaf, whereas Kir4.1+/- mice react like wild-type mice to acoustic stimuli. In Kir4.1-/- mice, the Reissner membrane is collapsed, the tectorial membrane is swollen, and type I hair cells and spiral ganglion neurons as well as their central processes degenerate over the first postnatal weeks. In the vestibular ganglia, neuronal cell death with apoptotic features is also observed. Immunostaining reveals that Kir4.1 is strongly expressed in stria vascularis of wild-type but not Kir4.1-/- mice. Within the spiral ganglion, Kir4.1 labeling was detected on satellite cells surrounding spiral ganglion neurons and axons. We conclude that Kir4.1 is crucial for normal development of the cochlea and hearing, via two distinct aspects of extracellular K(+) homeostasis: (1). in stria vascularis, Kir4.1 helps to generate the cochlear endolymph; and (2). in spiral and vestibular ganglia, Kir4.1 in surrounding glial cells helps to support the spiral and vestibular ganglion neurons and their projecting axons.
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Affiliation(s)
- Nora Rozengurt
- Department of Pathology, UCLA School of Medicine, Los Angeles, CA 90095, USA
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De Leenheer EMR, Huygen PLM, Coucke PJ, Admiraal RJC, van Camp G, Cremers CW. Longitudinal and cross-sectional phenotype analysis in a new, large Dutch DFNA2/KCNQ4 family. Ann Otol Rhinol Laryngol 2002; 111:267-74. [PMID: 11915881 DOI: 10.1177/000348940211100312] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We analyzed hearing thresholds, speech recognition scores, and vestibular responses in 32 affected persons in a large family with DFNA2/KCNQ4-related hearing impairment caused by a W276S missense mutation. Linear regression analysis of individual longitudinal data revealed significant threshold progression (1 dB/y) and offset (at age zero). The mean offset thresholds were 5, 21, 40, 39, 31, and 51 dB hearing level (HL) at 0.25, 0.5, 1, 2, 4, and 8 kHz, respectively. Cross-sectional analysis of last-visit thresholds against age produced less-steep slopes and higher offset thresholds. Nonlinear regression analysis of last-visit phoneme recognition scores against age in 25 cases showed that speech recognition did not deteriorate before the third decade. A hyperactive vestibuloocular reflex was found in 3 of 11 cases: 2 persons were especially susceptible to motion sickness. Persons with this KCNQ4 mutation showed congenital, progressive high-frequency impairment without substantial loss of speech recognition during the first decades of life.
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Affiliation(s)
- Els M R De Leenheer
- Department of Otorhinolaryngology, University Medical Center St Radboud Nijmegen, The Netherlands
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Beisel KW, Nelson NC, Delimont DC, Fritzsch B. Longitudinal gradients of KCNQ4 expression in spiral ganglion and cochlear hair cells correlate with progressive hearing loss in DFNA2. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2000; 82:137-49. [PMID: 11042367 DOI: 10.1016/s0169-328x(00)00204-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mutations in the human KCNQ4 gene were recently found by Kubisch et al. [Cell 96 (1999) 437-446] to cause a non-syndromic, autosomal dominant, progressive hearing loss, DFNA2. The mouse Kcnq4 orthologue was previously localized to the outer hair cells (OHCs) of the inner ear, suggesting the pathophysiological effects were due to dysfunctional OHCs. Yet, OHC dysfunction does not provide a plausible explanation for the progressive nature of the frequency specific hearing loss. We have re-examined and extended the expression analyses of KCNQ4 in the murine inner ear using RT-PCR and whole mount in situ hybridization. Our results confirmed that the rat KCNQ4 orthologue is expressed in both inner and outer hair cells. Reciprocal longitudinal gradients were found in inner hair cells (IHCs) and OHCs. The strongest expression of KCNQ4 in IHCc was in the base of the cochlea and in the apex for OHCs. Similar to the IHCs, a basal to apical gradient was present in the spiral sensory neurons. IHCs mediate hearing via their afferent sensory neurons, whereas OHCs function as active cochlear amplifiers. The complete absence of OHCs leads only to severe sensitivity reduction, but not complete hearing loss. Our data suggest that the primary defect leading to initial high frequency loss and subsequent progressive hearing loss for all frequencies may be due to spiral ganglion and/or IHC dysfunction, rather than an OHC aberration.
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Affiliation(s)
- K W Beisel
- Department of Genetics, Center for Hereditary Communication Disorders, Boys Town National Research Hospital, 555 North 30th Street, Omaha, NE 68178, USA.
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