OTOF mutations revealed by genetic analysis of hearing loss families including a potential temperature sensitive auditory neuropathy allele

Introduction

The majority of hearing loss in children can be accounted for by genetic causes. Non‐syndromic hearing loss accounts for 80% of genetic hearing loss in children, with mutations in DFNB1/GJB2 being by far the most common cause. Among the second tier genetic causes of hearing loss in children are mutations in the DFNB9/OTOF gene.

Methods

In total, 65 recessive non‐syndromic hearing loss families were screened by genotyping for association with the DFNB9/OTOF gene. Families with genotypes consistent with linkage or uninformative for linkage to this gene region were further screened for mutations in the 48 known coding exons of otoferlin.

Results

Eight OTOF pathological variants were discovered in six families. Of these, Q829X was found in two families. We also noted 23 other coding variant, believed to have no pathology. A previously published missense allele I515T was found in the heterozygous state in an individual who was observed to be temperature sensitive for the auditory neuropathy phenotype.

Conclusions

Mutations in OTOF cause both profound hearing loss and a type of hearing loss where otoacoustic emissions are spared called auditory neuropathy.     

Speech perception benefits of internet versus conventional telephony for hearing-impaired individuals

Background

Telephone communication is a challenge for many hearing-impaired individuals. One important technical reason for this difficulty is the restricted frequency range (0.3–3.4 kHz) of conventional landline telephones. Internet telephony (voice over Internet protocol [VoIP]) is transmitted with a larger frequency range (0.1–8 kHz) and therefore includes more frequencies relevant to speech perception. According to a recently published, laboratory-based study, the theoretical advantage of ideal VoIP conditions over conventional telephone quality has translated into improved speech perception by hearing-impaired individuals. However, the speech perception benefits of nonideal VoIP network conditions, which may occur in daily life, have not been explored. VoIP use cannot be recommended to hearing-impaired individuals before its potential under more realistic conditions has been examined.

Objective

To compare realistic VoIP network conditions, under which digital data packets may be lost, with ideal conventional telephone quality with respect to their impact on speech perception by hearing-impaired individuals.

Methods

We assessed speech perception using standardized test material presented under simulated VoIP conditions with increasing digital data packet loss (from 0% to 20%) and compared with simulated ideal conventional telephone quality. We monaurally tested 10 adult users of cochlear implants, 10 adult users of hearing aids, and 10 normal-hearing adults in the free sound field, both in quiet and with background noise.

Results

Across all participant groups, mean speech perception scores using VoIP with 0%, 5%, and 10% packet loss were 15.2% (range 0%–53%), 10.6% (4%–46%), and 8.8% (7%–33%) higher, respectively, than with ideal conventional telephone quality. Speech perception did not differ between VoIP with 20% packet loss and conventional telephone quality. The maximum benefits were observed under ideal VoIP conditions without packet loss and were 36% (P = .001) for cochlear implant users, 18% (P = .002) for hearing aid users, and 53% (P = .001) for normal-hearing adults. With a packet loss of 10%, the maximum benefits were 30% (P = .002) for cochlear implant users, 6% (P = .38) for hearing aid users, and 33% (P = .002) for normal-hearing adults.

Conclusions

VoIP offers a speech perception benefit over conventional telephone quality, even when mild or moderate packet loss scenarios are created in the laboratory. VoIP, therefore, has the potential to significantly improve telecommunication abilities for the large community of hearing-impaired individuals.     

Speech and non-speech processing in children with phonological disorders: an electrophysiological study

OBJECTIVE:

To determine whether neurophysiological auditory brainstem responses to clicks and repeated speech stimuli differ between typically developing children and children with phonological disorders.

INTRODUCTION:

Phonological disorders are language impairments resulting from inadequate use of adult phonological language rules and are among the most common speech and language disorders in children (prevalence: 8 ‐ 9%). Our hypothesis is that children with phonological disorders have basic differences in the way that their brains encode acoustic signals at brainstem level when compared to normal counterparts.

METHODS:

We recorded click and speech evoked auditory brainstem responses in 18 typically developing children (control group) and in 18 children who were clinically diagnosed with phonological disorders (research group). The age range of the children was from 7‐11 years.

RESULTS:

The research group exhibited significantly longer latency responses to click stimuli (waves I, III and V) and speech stimuli (waves V and A) when compared to the control group.

DISCUSSION:

These results suggest that the abnormal encoding of speech sounds may be a biological marker of phonological disorders. However, these results cannot define the biological origins of phonological problems. We also observed that speech‐evoked auditory brainstem responses had a higher specificity/sensitivity for identifying phonological disorders than click‐evoked auditory brainstem responses.

CONCLUSIONS:

Early stages of the auditory pathway processing of an acoustic stimulus are not similar in typically developing children and those with phonological disorders. These findings suggest that there are brainstem auditory pathway abnormalities in children with phonological disorders.     

Noise-induced tinnitus: auditory evoked potential in symptomatic and asymptomatic patients

OBJECTIVES:

We evaluated the central auditory pathways in workers with noise-induced tinnitus with normal hearing thresholds, compared the auditory brainstem response results in groups with and without tinnitus and correlated the tinnitus location to the auditory brainstem response findings in individuals with a history of occupational noise exposure.

METHOD:

Sixty individuals participated in the study and the following procedures were performed: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25–8 kHz and auditory brainstem response.

RESULTS:

The mean auditory brainstem response latencies were lower in the Control group than in the Tinnitus group, but no significant differences between the groups were observed. Qualitative analysis showed more alterations in the lower brainstem in the Tinnitus group. The strongest relationship between tinnitus location and auditory brainstem response alterations was detected in individuals with bilateral tinnitus and bilateral auditory brainstem response alterations compared with patients with unilateral alterations.

CONCLUSION:

Our findings suggest the occurrence of a possible dysfunction in the central auditory nervous system (brainstem) in individuals with noise-induced tinnitus and a normal hearing threshold.     

Development and analysis of a low-cost screening tool to identify and classify hearing loss in children: a proposal for developing countries

OBJECTIVES:

A lack of attention has been given to hearing health in primary care in developing countries. A strategy involving low-cost screening tools may fill the current gap in hearing health care provided to children. Therefore, it is necessary to establish and adopt lower-cost procedures that are accessible to underserved areas that lack other physical or human resources that would enable the identification of groups at risk for hearing loss. The aim of this study was to develop and analyze the efficacy of a low-cost screening tool to identify and classify hearing loss in children.

METHODS:

A total of 214 2-to-10 year-old children participated in this study. The study was conducted by providing a questionnaire to the parents and comparing the answers with the results of a complete audiological assessment. Receiver operating characteristic (ROC) curves were constructed, and discriminant analysis techniques were used to classify each child based on the total score.

RESULTS:

We found conductive hearing loss in 39.3% of children, sensorineural hearing loss in 7.4% and normal hearing in 53.3%. The discriminant analysis technique provided the following classification rule for the total score on the questionnaire: 0 to 4 points – normal hearing; 5 to 7 points – conductive hearing loss; over 7 points – sensorineural hearing loss.

CONCLUSION:

Our results suggest that the questionnaire could be used as a screening tool to classify children with normal hearing or hearing loss and according to the type of hearing loss based on the total questionnaire score.     

Supporting Informed Decision Making Online in 20 Minutes: An Observational Web-log Study of a PSA Test Decision Aid

Background

Web-based decision aids are known to have an effect on knowledge, attitude, and behavior; important components of informed decision making. We know what decision aids achieve in randomized controlled trials (RCTs), but we still know very little about how they are used and how this relates to the informed decision making outcome measures.

Objective

To examine men''s use of an online decision aid for prostate cancer screening using website transaction log files (web-logs), and to examine associations between usage and components of informed decision making.

Methods

We conducted an observational web-log analysis of users of an online decision aid, Prosdex. Men between 50 and 75 years of age were recruited for an associated RCT from 26 general practices across South Wales, United Kingdom. Men allocated to one arm of the RCT were included in the current study. Time and usage data were derived from website log files. Components of informed decision making were measured by an online questionnaire.

Results

Available for analysis were 82 web-logs. Overall, there was large variation in the use of Prosdex. The mean total time spent on the site was 20 minutes. The mean number of pages accessed was 32 (SD 21) out of a possible 60 pages. Significant associations were found between increased usage and increased knowledge (Spearman rank correlation [ρ] = 0.69, P < .01), between increased usage and less favorable attitude towards PSA testing (ρ = -0.52, P < .01), and between increased usage and reduced intention to undergo PSA testing (ρ = -0.44, P < .01). A bimodal distribution identified two types of user: low access and high access users.

Conclusions

Increased usage of Prosdex leads to more informed decision making, the key aim of the UK Prostate Cancer Risk Management Programme. However, developers realistically have roughly 20 minutes to provide useful information that will support informed decision making when the patient uses a web-based interface. Future decision aids need to be developed with this limitation in mind. We recommend that web-log analysis should be an integral part of online decision aid development and analysis.

Trial Registration

ISRCTN48473735; http://www.controlled-trials.com/ISRCTN48473735 (Archived by WebCite at http://www.webcitation.org/5pqeF89tS)     

Sensitivity and specificity of auditory steady-state response testing

INTRODUCTION:

The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones.

OBJECTIVE:

The aim of this study was to determine the sensitivity and specificity of auditory steady‐state response testing in detecting lesions and dysfunctions of the central auditory nervous system.

METHODS:

Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady‐state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady‐state response‐estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated.

RESULTS:

Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady‐state response‐estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group.

DISCUSSION:

Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR‐estimated thresholds and actual behavioral thresholds; ASSR‐estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR‐estimated thresholds and the behavioral thresholds is impaired temporal resolution.

CONCLUSIONS:

The overall sensitivity of auditory steady‐state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.     

(Central) Auditory Processing: the impact of otitis media

OBJECTIVE:

To analyze auditory processing test results in children suffering from otitis media in their first five years of age, considering their age. Furthermore, to classify central auditory processing test findings regarding the hearing skills evaluated.

METHODS:

A total of 109 students between 8 and 12 years old were divided into three groups. The control group consisted of 40 students from public school without a history of otitis media. Experimental group I consisted of 39 students from public schools and experimental group II consisted of 30 students from private schools; students in both groups suffered from secretory otitis media in their first five years of age and underwent surgery for placement of bilateral ventilation tubes. The individuals underwent complete audiological evaluation and assessment by Auditory Processing tests.

RESULTS:

The left ear showed significantly worse performance when compared to the right ear in the dichotic digits test and pitch pattern sequence test. The students from the experimental groups showed worse performance when compared to the control group in the dichotic digits test and gaps-in-noise. Children from experimental group I had significantly lower results on the dichotic digits and gaps-in-noise tests compared with experimental group II. The hearing skills that were altered were temporal resolution and figure-ground perception.

CONCLUSION:

Children who suffered from secretory otitis media in their first five years and who underwent surgery for placement of bilateral ventilation tubes showed worse performance in auditory abilities, and children from public schools had worse results on auditory processing tests compared with students from private schools.     

The box simulator is useful for training novice endoscopists in basic endoscopic techniques

Purpose

The present study was aimed at evaluating the usefulness of box simulators for training novice endoscopists.

Materials and Methods

An explanation of the goals, contents, and features of the simulator was given to study participants. The participants then received "hands-on training" in gastrointestinal endoscopy techniques using a box simulator. Subsequently, they were asked to answer 19 structured questions about the simulator. Ratings were scored on a scale from 1 to 5 for questions concerning their first impression of the simulator. Questions on the usefulness of the simulator and the training course were answered as "agree", "disagree", or "no opinion".

Results

A total of 32 participants filled out the questionnaire. The mean scores on the simulator''s usefulness, features, and realistic movements before the training were between 1.5 and 2.0. There were no significant differences between the mean values of the scores given by novice users compared to non-novice users. However, after receiving training on the simulator, 90.6% of the participants considered the box simulator a generally useful tool for learning basic endoscopic techniques, and 90.6% agreed that the simulator was useful for improving hand-eye coordination.

Conclusion

Box simulators may be useful for training novice endoscopists in basic gastrointestinal endoscopic techniques.     

Auditory evoked potentials: predicting speech therapy outcomes in children with phonological disorders

OBJECTIVES:

This study investigated whether neurophysiologic responses (auditory evoked potentials) differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy.

METHODS:

The participants included 24 typically developing children (Control Group, mean age: eight years and ten months) and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months). Additionally, 12 study group children were enrolled in speech therapy (Study Group 1), and 11 were not enrolled in speech therapy (Study Group 2). The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups.

RESULTS:

Latency differences were observed between the groups (the control and study groups) regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy.

CONCLUSION:

The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy.     

Does a decision aid help physicians to detect chronic obstructive pulmonary disease?

Background

Numerous decision aids have been developed recently, but the value they add above that of the initial clinical assessment is not well known.

Aim

To quantify whethera formal decision aid for chronic obstructive pulmonary disease (COPD) adds diagnostic information, above the physician''s clinical assessment.

Design and setting

Subanalysis of a diagnostic study in Dutch primary care.

Method

Sixty-five primary care physicians included 357 patients who attended for persistent cough and were not known to have COPD. The physicians estimated the probability of COPD after short history taking and physical examination. After this, the presence or absence of COPD was determined using results of extensive diagnostic work-up. The extent to which an 8-item decision aid for COPD, which included only symptoms and signs, added diagnostic value above the physician''s estimation was quantified by the increase of the area under the receiver operating characteristic curve (ROC area), and the improvement in diagnostic risk classification across two classes: ‘low probability of COPD’ (<20%) and ‘possible COPD’ (≥20%).

Results

One hundred and four patients (29%) had COPD. Adding the decision aid to the clinical assessment increased the ROC area from 0.75 (95% confidence interval [CI] = 0.70 to 0.81) to 0.84 (95% CI = 0.80 to 0.89) (P<0.005), and improved the diagnostic risk classification of the patients, such that 35 fewer patients needed spirometry testing and eight fewer COPD cases were missed.

Conclusion

A short decision aid for COPD added diagnostic value to the physician''s clinical assessment.     

Utilisation of insecticide treated nets among pregnant women in Gulu: a post conflict district in northern Uganda

Background

Malaria during pregnancy causes severe anaemia, placental malaria or death to the mother while the fetus may be aborted or stillborn.

Objective

To establish the prevalence and factors associated with Insecticide Treated Net (ITN) utilisation among pregnant women in a post conflict Internally Displaced Persons (IDP) camps of Gulu district.

Methods

We conducted cross-sectional study in 20 IDP camps in which 769 pregnant women were interviewed for ITN utilisation the night before the survey. The 20 IDP camps were selected using simple random sampling technique as clusters. Households that had pregnant women were then consecutively selected. Data were entered in EpiData 3.1 and analyzed using STATA11.

Results

35% of pregnant women (95% CI 31% – 38%) had utilised ITNs. Factors that promoted ITN utilisation includes: antenatal visit (AOR 1.90, p-value 0.000); ITN awareness (AOR 1.57, p-value 0.011), and willingness to purchase ITN (AOR 2.12, p-value 0.000). Factors which hinder ITN utilisation were: hours taken to reach health centre (AOR 0.64, p-value 0.050) and being single/widow/divorced (AOR 0.22, p-value 0.000).

Conclusion

Majority of the respondents were not utilising ITN. Therefore, leaders in Gulu district should encourage pregnant woman to acquire and use ITN to reduce their vulnerability to malaria.     

Audiometric Patterns in Ototoxicity After Radiotherapy and Chemotherapy in Patients of Head and Neck Cancers

Introduction:

Inspite of various strategies adopted to protect the sensitive structures during organ preservation strategies, radiation damage can occur from the pharyngotympanic tube to the brain stem auditory pathway causing hearing loss. The purpose of this study is to evaluate the audiometric abnormalities and characterize them among the patients of head and neck cancers who have undergone radiotherapy (RT) and chemoradiation therapy (CT+RT).

Materials and Methods:

Sixty-six histopathologically proven head and neck cancer patients receiving RT and 34 patients receiving concomitant CT + RT underwent evaluation for audiometric abnormalities from 1^st September 2010 to 31^st August 2012.

Results:

Hearing losses were predominately of sensorineural type and mild. Patients who received concomitant CT+RT experienced greater sensorineural hearing loss compared with patients treated with RT alone. A paired sample t-test was conducted to compare the hearing losses before therapy and 6 and 12 months after therapy and was found to be significant (P < 0.05). It was found that hearing loss was persistent. Significant difference was found in the proportion of hearing loss after RT and RT+CT (P < 0.05) after 1 month. In addition, mixed hearing loss occurred due to damage to the middle ear contents and can be improved if intervened appropriately.     

Two Modes of Weight Training Programs and Patellar Stabilization

Context:

Underconditioned patellar stabilizing muscles could be a predisposing factor for patellar instability.

Objective:

To examine the effect of 2 modes of weight training on the size of the vastus medialis obliquus (VMO), the resting position and passive mobility of the patella, and the strength of the knee extensor muscles.

Design:

Prospective intervention, repeated measures in 3 groups.

Setting:

Orthopaedic and sports sciences research laboratory.

Patients or Other Participants:

48 healthy adults free from back and lower extremity injuries.

Intervention(s):

Participants were randomly assigned to muscle hypertrophy training, muscle strength training, or the control group. Those in the training groups pursued training 3 times per week for 8 weeks.

Main Outcome Measure(s):

Magnetic resonance imaging and ultrasound cross-sectional area of the VMO, patellar tilt angle on magnetic resonance imaging, instrumented passive patellar mobility, and isometric knee extension torque of the dominant leg.

Results:

Participants in both training groups had comparable gains in VMO size, passive patellar stability, and knee extension force, all of which were greater than for the control group (P < .05).

Conclusions:

Both short-term muscle hypertrophy and strength training programs can reinforce the patellar stabilizers in previously untrained volunteers.     

Cost effectiveness of a web-based decision aid for parents deciding about MMR vaccination: a three-arm cluster randomised controlled trial in primary care

Background

Levels of measles in England and Wales are at their highest for 18 years, and strategies targeting the different groups of parents who do not vaccinate their children continue to be needed. Decision aids for decisions regarding childhood immunisation appear to be effective in achieving an increase in vaccine uptake but their cost effectiveness is unknown.

Aim

To assess the cost effectiveness of a web-based decision aid to increase uptake of the MMR vaccine.

Design and setting

Economic evaluation conducted alongside a cluster randomised controlled trial using urban GP practices in the north of England.

Method

Fifty GP practices in the north of England were randomised to one of three trial arms: decision aid, leaflet, usual practice. A total of 220 first-time parents (child aged 3–12 months) were recruited. Parents self-reported their contacts with the NHS and other previous/expected resource utilisation; associated costs were calculated. Vaccine-uptake data were collected from GP practices. A cost-effectiveness analysis was undertaken and provided the incremental cost per first-vaccine uptake. Multiple imputation was used to account for missing data and findings were adjusted for baseline differences in parents’ levels of decisional conflict regarding MMR vaccination.

Results

Of the 220 first-time parents recruited to the study, 179 completed the baseline and post-intervention questionnaires. MMR uptake was highest for those receiving the decision aid (42 out of 42, 100%) versus usual practice (61 out of 62, 98%) and leaflet arm (69 out of 75, 92%), and was associated with lower cost (–£9.20 versus usual practice and –£7.17 versus leaflet).

Conclusion

The decision aid has a high chance of being cost effective, regardless of the value placed on obtaining additional vaccinations. It also appears to offer an efficient means of decision support for parents.     

Audiological manifestations in HIV-positive adults

OBJECTIVE:

To characterize the findings of behavioral hearing assessment in HIV-positive individuals who received and did not receive antiretroviral treatment.

METHODS:

This research was a cross-sectional study. The participants were 45 HIV-positive individuals (18 not exposed and 27 exposed to antiretroviral treatment) and 30 control-group individuals. All subjects completed an audiological evaluation through pure-tone audiometry, speech audiometry, and high-frequency audiometry.

RESULTS:

The hearing thresholds obtained by pure-tone audiometry were different between groups. The group that had received antiretroviral treatment had higher thresholds for the frequencies ranging from 250 to 3000 Hz compared with the control group and the group not exposed to treatment. In the range of frequencies from 4000 through 8000 Hz, the HIV-positive groups presented with higher thresholds than did the control group. The hearing thresholds determined by high-frequency audiometry were different between groups, with higher thresholds in the HIV-positive groups.

CONCLUSION:

HIV-positive individuals presented poorer results in pure-tone and high-frequency audiometry, suggesting impairment of the peripheral auditory pathway. Individuals who received antiretroviral treatment presented poorer results on both tests compared with individuals not exposed to antiretroviral treatment.     

Upper GI bleeding among neonates admitted to Mulago Hospital,Kampala, Uganda: a prospective cohort study

Background

The World Health Organization (WHO) reports estimate that 85% of newborn deaths are due to infections, prematurity and fetal distress. These conditions are risk factors for upper GI bleeding (UGIB) in sick neonates. UGIB is associated with poor neonatal outcomes such as prolonged hospitalisation and poor weight gain. The magnitude of UGIB and its contribution to neonatal morbidity has not been described in most low income countries.

Objective

To determine the occurrence and factors associated with UGIB among neonates admitted to the Special Care Unit (SCU) of Mulago Hospital.

Methods

This was a prospective single cohort study where neonates admitted within 24 hours of birth were consecutively enrolled and followed up for seven days. Gastric aspirates from the neonates were examined daily over a period of 7 days using Guaiac and Apt tests for evidence of UGIB. Data on occurrence of UGIB has been presented as proportions and Odds Ratios for associated factors.

Results

Out of 191 neonates, 44 (23 %) developed UGIB. Factors independently associated with UGIB included cyanosis in the neonate [OR 5.8; (95% CI; 1.8 – 19.1) p-value 0.004], neonatal seizures [OR 12.6; (95% CI 2.3 – 70.5); p-value 0.004] and birth asphyxia [OR 6.3; (95% CI 1.9 – 21.6); p-value 0.003].

Conclusions

In the first seven days of life, UGIB occurred in 1:4 neonates. Factors independently associated with UGIB included birth asphyxia, cyanosis in the neonate and neonatal seizures.     

CRYM mutations cause deafness through thyroid hormone binding properties in the fibrocytes of the cochlea

Background

In a search for mutations of μ‐crystallin (CRYM), a taxion specific crystalline which is also known as an NADP regulated thyroid hormone binding protein, two mutations were found at the C‐terminus in patients with non‐syndromic deafness.

Objective

To investigate the mechanism of hearing loss caused by CRYM mutations

Methods

T3 binding activity of mutant μ‐crystallin was compared with that of wild‐type μ‐crystallin, because μ‐crystallin is known to be identical to T3 binding protein. To explore the sites within the cochlea where μ‐crystallin is functioning, its localisation in the mouse cochlea was investigated immunocytochemically using a specific antibody.

Results

One mutant was shown to have no binding capacity for T3, indicating that CRYM mutations cause auditory dysfunction through thyroid hormone binding properties. Immunocytochemical results indicated that μ‐crystallin was distributed within type II fibrocytes of the lateral wall, which are known to contain Na,K‐ATPase.

Conclusions

CRYM mutations may cause auditory dysfunction through thyroid hormone binding effects on the fibrocytes of the cochlea. μ‐Crystallin may be involved in the potassium ion recycling system together with Na,K‐ATPase. Future animal experiments will be necessary to confirm a causal relation between Na,K‐ATPase, T3, and deafness.