Expression of drug metabolizing enzymes and transporters in the cochlea: Implications for drug delivery and ototoxicity

Inner ear drug delivery is a major area of research and development, but relatively little is known about basic drug metabolism in the cochlea. Additionally, the use of potentially ototoxic drugs such as NSAIDs, chemotherapeutics and aminoglycosides is common, but little is known about the role of metabolism in ototoxicity of those drugs. To address those issues, we compared expression of major Cytochromes P450 (Cyps), UDP-glucuronosyl-transferases (Ugts), sulfotransferases (Sults), and drug transporters between cochleae and liver, an organ with high expression, in mice using qPCR and enzyme kinetics. Together, the tested drug-metabolizing enzymes (DMEs) and transporters account for metabolism of approximately 70-80% of all medically important drugs in the body. Expression of most Cyps was low in the cochlea compared to liver, but three displayed similar expression levels to the liver, and one (Cyp2c65) had significantly higher levels of expression in the cochlea (1.9 ± 0.06 fold vs. liver). Enzyme kinetics revealed undetectable levels of p450 activity in the cochlea, especially as compared to the liver. Similar results were obtained for expression of Ugts and Sults. Interestingly, expression of most transporters was also low, with one major exception: Mdr1/P-glycoprotein (P-gp), which is generally thought to be highly expressed in liver and poorly expressed in most of the nervous system, was 3-fold greater in cochlea. Importantly, P-gp is known to protect other tissues from toxicity of cancer drugs by acting as an efflux pump. Our data demonstrate overall low levels of expression of DMEs and transporters in the cochlea, and identify a few that may be important to consider when designing and testing drugs for local delivery to the inner ear.

Annual hearing screening in girls with Turner Syndrome: Results from the first three years in Glasgow

BACKGROUND

Hearing loss is prevalent in girls with Turner Syndrome (TS). A number of cross-sectional studies have confirmed that conductive hearing loss due to middle ear disease and permanent, progressive sensorineural hearing loss are both very common and often unrecognised in TS. Hearing screening has been suggested by many authors and is recommended in some recent national audiology guidelines (every 3-5 years in an international consensus statement, every 1-2 years in the USA and every year in the UK). The effectiveness of such regular hearing screening has not been assessed before.

STUDY AIMS AND METHODS

In January 2016 we began a programme of annual hearing screening for all girls attending the West of Scotland TS clinic. We have collected data on age, karyotype, ear and hearing symptoms, otoscopy findings, audiometric test results and subsequent outcomes for the first three years of our programme. Our aim is to assess whether this screening programme is an effective use of resources, with a worthwhile rate of detecting new otological problems and without an excessive additional workload for the audiology department.

RESULTS

Twenty-six girls participated in the screening programme and 8 of these had no hearing issues or ear abnormalities at any time over the 3 years. Two girls had cholesteatoma, 4 had tympanic membrane retractions and/or perforations, and 9 had OME (of which 6 were transient and 3 persistent, with 2 of these requiring treatment). One cholesteatoma, one perforation and one persistent OME were already known about but all other diagnoses were new as a result of the screening programme. Five girls have persistent conductive hearing loss (plus another 6 who had a transient episode of conductive loss due to middle ear fluid) and 6 have some degree of sensorineural hearing loss (3 purely sensorineural, 3 mixed). At the time that a hearing loss was diagnosed, the parents had concerns about the hearing in 4 cases and no concerns in 12. Six girls have been fitted with hearing aids since we started the screening programme, each for different indications (sensorineural hearing loss in two cases, and one case each of persistent OME, post cholesteatoma surgery, tympanic membrane perforation and unilateral tympanic membrane retraction respectively). Two girls have had ear surgery as a result of referral from the programme (one for ventilation tubes, one for cholesteatoma).

CONCLUSIONS

The screening programme has picked up ear disease in 69% of girls with TS with only a small additional workload for the audiology department. The ongoing detection of new problems in the second and third years of the programme attests to the value of continued regular hearing screening for girls with TS.

Receptive and productive speech and language abilities in hearing-impaired children with German as a second language

OBJECTIVES

Many studies examining early bilingualism in migrant populations focus on the development of the first language. As language acquisition is closely related to the hearing development, there is a critical need to investigate language development in hearing-impaired children being raised bilingually who were fitted with cochlear implants and/or hearing aids. Therefore, this research project aimed to study the linguistic development of hearing-impaired children being raised with German as a second language who were provided with hearing aids or cochlear implants. Further, the language development of these children is compared with that of hearing-impaired children being raised in a monolingual environment and with normal-hearing children being raised bilingually.

METHODS

In this prospective study, we analyzed data from 95 typically developing children with hearing loss (43 bilingual and 52 monolingual) aged 3;0 to 10;11 (years; months) on four language measures in German: receptive vocabulary, productive vocabulary, receptive grammar, productive grammar (sentence repetition). Additionally, 30 bilingual children with normal hearing were included in this study.

RESULTS

44 children were provided with hearing aids in both ears; 34 used cochlear implants bilaterally and 17 were fitted bimodally. Statistical analysis showed that bilingual hearing-impaired children scored significantly poorer than monolingual hearing-impaired children.

CONCLUSION

Hearing-impaired children being raised bilingually should have speech and language examinations on a regular basis. An examination of both languages would be desirable in order to be able to fully assess speech and language acquisition.

CSHCN with hearing difficulties: Disparities in access and quality of care

BACKGROUND

Hearing difficulties (HD) affect a sizable minority of children in the United States and can have a significant impact on child development. Children with HD may face barriers around language development, communication abilities, learning, and social interactions, which in turn can affect multiple aspects of their lives.

OBJECTIVE/HYPOTHESIS

Little is known about the extent to which children with HD have access to a system of care and we hypothesize that this population may experience significant unmet needs.

METHODS

In this cross-sectional study, using bivariate and multivariable regression models, we analyzed data from the 2009/2010 National Survey of Children with Special Health Care Needs (NS-CSHCN). Selected survey items were used to assess health and healthcare characteristics of CSHCN with some level of HD (n = 2,315) compared to those without HD (n = 37,851). The study sample included 40,242 CSHCN aged 0-17 years, whose caregivers responded to the survey.

RESULTS

Approximately 694,000 CSHCN in the U.S. were reported to have any level of HD, representing 6.3% of the CSHCN population. Compared to CSHCN without HD, those with HD were less likely to have access to a medical home, community services, or have adequate health insurance.

CONCLUSIONS

Significant deficits in medical home access, adequate insurance, and accessibility of community-based services are evident for CSHCN with HD. Families having knowledge of how and when to access community services and partner with providers in their child's health care is important for the overall health and wellbeing of this subpopulation of CSHCN.

EEG rhythms lateralization patterns in children with unilateral hearing loss are different from the patterns of normal hearing controls during speech-in-noise listening

Unilateral hearing loss constitutes a field of growing interest in the scientific community. In fact, this kind of patients represent a unique and physiological way to investigate how neuroplasticity overcame unilateral deafferentation by implementing particular strategies that produce apparently next- to- normal hearing behavioural performances. This explains why such patients have been underinvestigated for a long time. Thanks to the availability of techniques able to study the cerebral activity underlying the mentioned behavioural outcomes, the aim of the present research was to elucidate whether different electroencephalographic (EEG) patterns occurred in unilateral hearing loss (UHL) children in comparison to normal hearing (NH) controls during speech-in-noise listening. Given the intrinsic lateralized nature of such patients, due to the unilateral side of hearing impairment, the experimental question was to assess whether this would reflect a different EEG pattern while performing a word in noise recognition task varying the direction of the noise source. Results showed a correlation between the period of deafness and the cortical activity asymmetry toward the hearing ear side in the frontal, parietal and occipital areas in all the experimental conditions. Concerning alpha and beta activity in the frontal and central areas highlighted that in the NH group, the lateralization was always left-sided during the Quiet condition, while it was right-sided in noise conditions; this evidence was not, however, detected also in the UHL group. In addition, focusing on the theta and alpha activity in the frontal areas (Broca area) during noise conditions, while the activity was always left-lateralized in the NH group, it was ipsilateral to the direction of the background noise in the UHL group, and of a weaker extent than in NH controls. Furthermore, in noise conditions, only the UHL group showed a higher theta activity in the temporal areas ipsilateral to the side where the background noise was directed to. Finally, in the case of bilateral noise (background noise and word signal both coming from the same two sources), the theta and alpha activity in the frontal areas (Broca area) was left-lateralized in the case of the NH group and lateralized towards the side of the better hearing ear in the case of the UHL group. Taken together, this evidence supports the establishment of a particular EEG pattern occurrence in UHL children taking place in the frontal (Broca area), temporal and parietal lobes, probably physiologically established in order to deal with different sound and noise source directions.

Genotype-phenotype correlation analysis of MYO15A variants in autosomal recessive non-syndromic hearing loss

Background

MYO15A variants are responsible for human non-syndromic autosomal recessive deafness (DFNB3). The majority of MYO15A variants are associated with a congenital severe-to-profound hearing loss phenotype, except for MYO15A variants in exon 2, which cause a milder auditory phenotype, suggesting a genotype-phenotype correlation of MYO15A. However, MYO15A variants not in exon 2 related to a milder phenotype have also been reported, indicating that the genotype-phenotype correlation of MYO15A is complicated. This study aimed to provide more cases of MYO15A variation with diverse phenotypes to analyse this complex correlation.

Methods

Fifteen Chinese autosomal recessive non-syndromic hearing loss (ARNSHL) individuals with MYO15A variants (8 males and 7 females) from 14 unrelated families, identified by targeted gene capture of 127 known candidate deafness genes, were recruited. Additionally, we conducted a review of the literature to further analyses all reported MYO15A genotype-phenotype relationships worldwide.

Results

We identified 16 novel variants and 12 reported pathogenic MYO15A variants in 15 patients, two of which presented with a milder phenotype. Interestingly, one of these cases carried two reported pathogenic variants in exon 2, while the other carried two novel variants not in exon 2. Based on our literature review, MYO15A genotype-phenotype correlation analysis showed that almost all domains were reported to be correlated with a milder phenotype. However, variants in the N-terminal domain were more likely to cause a milder phenotype. Using next-generation sequencing (NGS), we also found that the number of known MYO15A variants with milder phenotypes in Southeast Asia has increased in recent years.

Conclusion

Our work extended the MYO15A variant spectrum, enriched our knowledge of auditory phenotypes, and tried to explore the genotype-phenotype correlation in different populations in order to investigate the cause of the complex MYO15A genotype-phenotype correlation.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0790-2) contains supplementary material, which is available to authorized users.

The Bonebridge active bone conduction system: a fast and safe technique for a middle fossa approach

BACKGROUND

The transmastoid pre-sigmoid approach is always the preferred choice for implantation of the Bonebridge active bone conduction system in patients with a normal anatomy. When an anatomical variant exists or a previous surgery has been performed, a retrosigmoid approach or middle fossa approach can be performed.

METHODS

The preferred surgical technique for a middle fossa approach is described. A 14 mm drill head (Neuro Drill) was used to create the bed at the squamous portion of the temporal bone. Surgical time and complication rate were analysed.

RESULTS

The surgical time was shorter than 30 minutes in all cases, and only 14 seconds were needed to create a 14 mm bone bed. No complications were observed during the follow-up period (6-45 months).

CONCLUSION

Use of the Neuro Drill for the middle fossa approach is an easy technique. It significantly decreases the surgical time, without increasing the complication rate.

Comparison of auditory brainstem response and auditory steady state response audiometry by evaluating the hearing thresholds obtained in children with different severity of hearing loss

Objectives:

To compare the hearing thresholds obtained with auditory brainstem response (ABR) and auditory steady state response (ASSR) audiometry in children with hearing loss.

Methods:

Hearing thresholds were obtained by ABR and ASSR in children who presented with suspicion of deafness at Ear, nose & throat department of Al-Nafees Medical College Hospital Islamabad, between January to August 2018. The mean hearing thresholds obtained by two tests were compared within each category of severity of deafness. Time taken by both tests was also compared.

Results:

A total of 57 patients (114 ears) were included in the study. Among them 27 (47.4%) were male and 30 (52.6%) were female. The mean age of patients at presentation was 42 months (±30.9) with age range from one to 12 years. Mean hearing thresholds obtained by click ABR, chirp ABR, ASSR (1, 2, 4 kHz) & ASSR (0.5, 1, 2, 4 kHz) was 56.25 (±27.61), 58.88 (±27.44), 58.03 (±21.26) & 56.35 (±22.86) respectively. Mean thresholds were comparable between click ABR & ASSR (1, 2, 4 kHz) and between chirp ABR & ASSR (0.5, 1, 2, 4 kHz) in all degrees of hearing loss categories except in those patients with normal hearing thresholds. The mean time taken by clicks ABR, chirp ABR and ASSR were four minutes seven seconds, three minutes 15 seconds and 16 minutes and 7 seconds respectively.

Conclusions:

Hearing thresholds obtained by ABR and ASSR are comparable in all categories of severity of hearing loss. The time taken by ABR is less as compared to ASSR.

Analysis between phenotypes and genotypes of inner ear malformation

BACKGROUND

The clinical characteristics of LVAS have attracted more and more attention, its audiology and imaging features have also been deeply studied.

OBJECTIVE

To analyze phenotypes, genotypes of EVA, and find out the relationship between them.

METHODS

Sixty EVA patients were tested by audiometry, temporal bone high-resolution CT and inner ear MRI. SNPscan technology were carried out after the patients signed informed consent. SPSS19.0 software was used.

RESULT

1. Three types malformations include EVA, EVA with Mondini and Mondini were found. They accounted for 48.20%, 40.10%, and 11.70%. 2. The SLC26A4 gene mutation frequency was (47/53) 88.68% in EVA patients. The most common genotype was c.919-2A > G/c.919-2A > G, accounting for 28.30%. The most common mutation type was c.9I9-2A > G. 3. GJB2 and SLC26A4 gene mutation frequencies were significantly different (χ2＝65.185, p<.001).

CONCLUSIONS

1. EVA patients with severe sensorineural hearing loss were always diagnosed in childhood and Cochlear implantation was feasible for these patients with the bilateral hearing loss. 2. SLC26A4 gene was closely related to EVA. 3. GJB2 and mtDNA genes were not responsible for EVA.

SIGNIFICANCE

The relationship between genotype and clinical phenotype provides a theoretical basis for future gene diagnosis and prevention and treatment of LVAS.

PMCA2 pump mutations and hereditary deafness

Hair cells of the inner ear detect sound stimuli, inertial or gravitational forces by deflection of their apical stereocilia. A small number of stereociliary cation-selective mechanotransduction (MET) channels admit K⁺ and Ca²⁺ ions into the cytoplasm promoting hair cell membrane depolarization and, consequently, neurotransmitter release at the cell basolateral pole. Ca²⁺ influx into the stereocilia compartment is counteracted by the unusual w/a splicing variant of plasma-membrane calcium-pump isoform 2 (PMCA2) which, unlike other PMCA2 variants, increases only marginally its activity in response to a rapid variation of the cytoplasmic free Ca²⁺ concentration ([Ca²⁺]_c). Missense mutations of PMCA2w/a cause deafness and loss of balance in humans. Mouse models in which the pump is genetically ablated or mutated show hearing and balance impairment, which correlates with defects in homeostatic regulation of stereociliary [Ca²⁺]_c, decreased sensitivity of mechanotransduction channels to hair bundle displacement and progressive degeneration of the organ of Corti. These results highlight a critical role played by the PMCA2w/a pump in the control of hair cell function and survival, and provide mechanistic insight into the etiology of deafness and vestibular disorders.

Hazardous Alcohol Consumption and the Risk of Hearing Impairment in Adults Based on the Korean National Health and Nutrition Survey: A Retrospective Study

Background and Objectives

To investigate the relationship between hearing impairment and alcohol drinking patterns in South Korean adults.

Subjects and Methods

Data collection was performed by Korean National Health and Nutrition Survey from January 1 to December 31, 2012. Data analyses were performed from February 20 to March 3, 2018. Data from 3,860 adults 20 years of age or older without a history of malignancy or chronic otitis media in the Korean National Health and Nutrition Survey 2012 database who participated in the health questionnaires, and who had available results from otologic examinations that included pure tone audiogram, were included. Pure-tone average hearing thresholds were calculated at 500, 1,000, 2,000, and 4,000 Hz. Hearing loss was defined as a pure-tone average >40 dB in one or both ears. The Alcohol Use Disorder Identification Test was used to evaluate drinking statuses of subjects. Data were analyzed using the complex-sample χ²-test of independence and a complex-sample logistic regression analysis.

Results

Of the 29,954,319 individuals in the weighted cross-sectional study population, 15,106,040 (50.4%) were men and 14,848,098 (49.6%) were women. A total of 8.1% of men and 7% of women had hearing impairment. The degrees of drinking with appropriate, risky, and hazardous drinking habits were 58.2, 32.1, and 9.7% among men; and 76.4, 12.5, and 11.1% among women, respectively. Among men, the odds ratio of hearing loss increased by 2.506 times when comparing hazardous and appropriate drinking (confidence interval, 1.083 to 5.800, p=0.002). Moderate alcohol consumption (≤2 drinks per day) was not protective for hearing in either group.

Conclusions

As hazardous drinking tends to coexist with hearing impairment in men, appropriate prevention and intervention strategies should be emphasized. A longitudinal study to investigate harmful drinking and the mechanism of hearing loss should be performed.

DOOR syndrome: A case report and its embryological basis

DOOR syndrome is an extremely rare genetic disorder. "DOOR″ is an acronym to describe the combination of: deafness, onychodystrophy, osteodystrophy and mental retardation. We present a patient, with all of the above-mentioned main symptoms, that was rehabilitated with convencional hearing aids. The presented case suggested that every case of deafness and abnormal nails and phalanges in the hands and feet should have a clinical diagnosis of possible DOOR syndrome. Based on embryological process, congenital abnormal nails or phalanges highlights the importance for detailed hearing screening.

[Clinical observation on the effect of glucocorticoid insensitivity on sudden sensorineural hearing loss patients]

Objective: To investigate the correlation between the proliferation inhibition effect of glucocorticoid (GC) on peripheral blood mononuclear cell (PBMC) and the pure tone average (PTA) improvement in SSNHL patients. Methods: Sixty inpatients with SSNHL were included from July 2013 to October 2015 in Nanjing Drum Tower Hospital, Medical School of Nanjing University. Peripheral venous blood was collected before receiving treatment, then the PBMC was isolated for GC proliferation inhibition. PBMCs of each patient were cultivated into 4 groups: Group A: PBMCs+ Medium; Group B: PBMCs+ Medium+ lipopolysaccharide (LPS, 1 μmol/L); Group C: PBMCs+ Medium+ LPS+ Dexamethasone; Group D: Medium. PBMCs were maintained in a humidified 5% CO(2) atmosphere at 37°C and were observed after 24 hours. 5-diphenyltetrazolium bromide (MTT) was used to measure PBMC proliferation inhibition rate. The PBMC proliferation inhibition rates were calculated according to the absorbance at 490 nm wavelength under a microtiter plate reader. Independent sample t tests of PBMC proliferation inhibition rate were performed between different groups. χ(2) tests were performed between gender, affected ear side, accompanied by vertigo or not, audiometric curve, time period from onset to treatment, PBMC proliferation inhibition rate and the improvement of pure tone average (PTA). Linear correlation analyses were performed between PBMC proliferation inhibition rate, the time period from onset to treatment and the hearing improvement. Results: The proliferation inhibition effect of GC on PBMC varied significantly among patients. The PBMC proliferation inhibition rate in GC insensitive group was lower than that in GC sensitive group (26.72%±21.82% vs 64.44%±25.48%, t=6.113, P<0.05). The PBMC proliferation inhibition rate in refractory group was lower than that in initial group (40.93%±28.57% vs 57.04%±31.19%, t=2.035, P=0.046). There was no statistical significance between gender, affected ear side, accompanied by vertigo or not, audiometric curve and the hearing improvement (χ(2) value was 2.320, 0.031, 2.143, 0.106, respectively, all P>0.05). Both in initial group and refractory group, the linear correlation analyses showed a significant positive correlation between PBMC proliferation inhibition rate and the PTA improvement (r value was 0.615, 0.657, respectively, all P<0.05), as well as a significant negative correlation between time period from onset to treatment and the PTA improvement(r value was -0.542, 0.370, respectively, all P<0.05). Conclusions: The proliferation inhibition rate of PBMC in vitro by GC is correlated with patients' hearing improvement. The proliferation inhibition test might be used to predict the sensitivity to GC treatment and be helpful for individualized treatment of SSNHLin clinical practice.

The additional genetic diagnosis of homozygous sickle cell disease in a patient with Waardenburg-Shah syndrome: a case report

Background

It is important that multiple genetic diagnoses are not missed. This case report describes the clinical features and management of a patient with co-inheritance of Waardenburg syndrome type 4 or Waardenburg-Shah syndrome, an extremely rare disease, and homozygous sickle cell disease not uncommon in the Caribbean. This case is unusual as it may be the first documented case of the co-inheritance of both these diseases. Given the commonality of sickle cell and related hemoglobinopathies, such combined disorders are likely to be under-reported. Importantly, reporting this case will add to the medical literature as it will raise awareness of the phenotypic manifestations of this disorder.

Case presentation

A 54-year-old Afro-Caribbean woman had a delayed diagnosis of homozygous sickle cell disease at 7 years of age by hemoglobin electrophoresis. The complications of sickle cell disease she experienced included bone pain, a chronic right leg ulcer, avascular necrosis of her left hip, and symptomatic cholelithiasis. This diagnosis was preceded by an earlier diagnosis of Waardenburg syndrome. The basis for the diagnosis of Waardenburg-Shah syndrome was the presence of pigmentary disturbances of her eyes (hypoplastic blue irides), congenital sensorineural hearing loss, and Hirschsprung’s disease. She was mute and complained of chronic constipation which required disimpaction on several occasions. She attended a school for the deaf and communicated via writing. A Duhamel procedure bypassing her rectum was performed at age 9. She died following an admission for acute chest syndrome complications.

Conclusion

Sickle cell disease can be diagnosed by newborn screening but, as in this case, may have a delayed presentation. The delay in diagnosis of homozygous sickle cell disease illustrates that other genetic disorders should be considered in patients who already have a diagnosis of one Mendelian disorder but show atypical features.

Is CT or MRI the optimal imaging investigation for the diagnosis of large vestibular aqueduct syndrome and large endolymphatic sac anomaly?

BACKGROUND AND PURPOSE

We explored whether there was a difference between measurements obtained with CT and MRI for the diagnosis of large vestibular aqueduct syndrome or large endolymphatic sac anomaly, and whether this influenced diagnosis on the basis of previously published threshold values (Valvassori and Cincinnati). We also investigated whether isolated dilated extra-osseous endolymphatic sac occurred on MRI. Secondary objectives were to compare inter-observer reproducibility for the measurements, and to investigate any mismatch between the diagnoses using the different criteria.

MATERIALS/METHODS

Subjects diagnosed with large vestibular aqueduct syndrome or large endolymphatic sac anomalies were retrospectively analysed. For subjects with both CT and MRI available (n = 58), two independent observers measured the midpoint and operculum widths. For subjects with MRI (± CT) available (n = 84), extra-osseous sac widths were also measured. Results There was no significant difference between the width measurements obtained with CT versus MRI. CT alone diagnosed large vestibular aqueduct syndrome or large endolymphatic sac anomalies in 2/58 (Valvassori) and 4/58 (Cincinnati), whilst MRI alone diagnosed them in 2/58 (Valvassori). There was 93% CT/MRI diagnostic agreement using both criteria. Only 1/84 demonstrated isolated extra-osseous endolymphatic sac dilatation. The MRI-based LVAS/LESA diagnosis was less dependent on which criteria were used. Midpoint measurements are more reproducible between observers and between CT/MR imaging modalities.

CONCLUSION

Supplementing MRI with CT results in additional diagnoses using either criterion, however, there is no net increased diagnostic sensitivity for CT versus MRI when applying the Valvassori criteria. Isolated enlargement of the extra-osseous endolymphatic sac is rare.

Antiepileptics and NO-precursors may be beneficial for stroke-like episodes

Pathogenesis and management of stroke-like episodes in mitochondrial disorders is under debate and no consensus has been reached thus far how this phenomenon should be managed. Frequently applied are nitric oxide (NO) precursors but a well-designed study confirming the effectiveness of such an approach is lacking. Administration of antiepileptic drugs can be meaningful if there is paroxysmal activity on EEG or if a patient presents with seizures. The case reported by Sakai et al. suggests that administration of antiepileptic drugs for a stroke-like episode may be beneficial even in the absence of seizures or paroxysmal EEG activity.

Building and repairing the stereocilia cytoskeleton in mammalian auditory hair cells

Despite all recent achievements in identification of the molecules that are essential for the structure and mechanosensory function of stereocilia bundles in the auditory hair cells of mammalian species, we still have only a rudimentary understanding of the mechanisms of stereocilia formation, maintenance, and repair. Important molecular differences distinguishing mammalian auditory hair cells from hair cells of other types and species have been recently revealed. In addition, we are beginning to solve the puzzle of the apparent life-long stability of the stereocilia bundles in these cells. New data link the stability of the cytoskeleton in the mammalian auditory stereocilia with the normal activity of mechanotransduction channels. These data suggest new ideas on how a terminally-differentiated non-regenerating hair cell in the mammalian cochlea may repair and tune its stereocilia bundle throughout the life span of the organism.

Differences in Emotion Recognition From Body and Face Cues Between Deaf and Hearing Individuals

Deaf individuals may compensate for the lack of the auditory input by showing enhanced capacities in certain visual tasks. Here we assessed whether this also applies to recognition of emotions expressed by bodily and facial cues. In Experiment 1, we compared deaf participants and hearing controls in a task measuring recognition of the six basic emotions expressed by actors in a series of video-clips in which either the face, the body, or both the face and body were visible. In Experiment 2, we measured the weight of body and face cues in conveying emotional information when intense genuine emotions are expressed, a situation in which face expressions alone may have ambiguous valence. We found that deaf individuals were better at identifying disgust and fear from body cues (Experiment 1) and in integrating face and body cues in case of intense negative genuine emotions (Experiment 2). Our findings support the capacity of deaf individuals to compensate for the lack of the auditory input enhancing perceptual and attentional capacities in the spared modalities, showing that this capacity extends to the affective domain.

Goya's Lost Hearing: A Twenty-First Century Perspective on Its Cause, Effects and Possible Treatment

Francisco Goya produced over 1,800 works during his long career, which earned him a reputation as one of the greatest artists of modern times. When he was 47, he developed a mysterious illness that destroyed his hearing, and for the next 35 years left him "deaf as a stump." Of the diagnoses proposed to date, Susac syndrome is the one most consistent with what little we do know of the character of that illness. If he were alive today, given the severity of his hearing loss, Goya would be treated with a cochlear implant, which might restore his ability to communicate in spoken language, though probably not to the level preceding his 1793 illness.

Novel deleterious mutation in MYO7A, TH and EVC2 in two Pakistani brothers with familial deafness

Objective

In Pakistan, 74% of consanguineous marriages are among the first cousins. Continuity of consanguineous marriages over generations increases the risk of recessive diseases such as deafness. The objective of this study was to investigate genetic origin of Pakistani deaf brothers with parents of consanguineous marriage.

Methods

DNA was extracted from the blood through Qiagen kit. Paired-end sequencing library was prepared according to protocol of Illumina's TruSight Rapid Capture kit and TruSight Inherited Disease Panel. Library was normalized and used for Next Generation Sequencing through MiSeq. NGS data were analyzed using various bioinformatics tools.

Results

Both brothers were found to have novel deleterious mutation in MYO7A (c.2476G>A) while the younger brother had additional novel deleterious mutation in TH (c.43C>T) and EVC2 (c.2614C>T) genes.

Conclusion

It is concluded that in addition to novel mutations in MYO7A, TH and EVC2, the CDH23 and GJB2 can also be responsible for deafness in the family with consanguineous marriages.

The power of language: Functional brain network topology of deaf and hearing in relation to sign language experience

Prolonged auditory sensory deprivation leads to brain reorganization. This is indicated by functional enhancement in remaining sensory systems and known as cross-modal plasticity. In this study we investigated differences in functional brain network topology between deaf and hearing individuals. We also studied altered functional network responses between deaf and hearing individuals with a recording paradigm containing an eyes-closed and eyes-open condition. Electroencephalography activity was recorded in a group of sign language-trained deaf (N = 71) and hearing people (N = 122) living in rural Africa. Functional brain networks were constructed from the functional connectivity between fourteen electrodes distributed over the scalp. Functional connectivity was quantified with the phase lag index based on bandpass filtered epochs of brain signal. We studied the functional connectivity between the auditory, somatosensory and visual cortex and performed whole-brain minimum spanning tree analysis to capture network backbone characteristics. Functional connectivity between different regions involved in sensory information processing tended to be stronger in deaf people during the eyes-closed condition in both the alpha and beta frequency band. Furthermore, we found differences in functional backbone topology between deaf and hearing individuals. The backbone topology altered during transition from the eyes-closed to eyes-open condition irrespective of deafness, but was more pronounced in deaf individuals. The transition of backbone strength was different between individuals with congenital, pre-lingual or post-lingual deafness. Functional backbone characteristics correlated with the experience of sign language. Overall, our study revealed more insights in functional network reorganization caused by auditory deprivation and cross-modal plasticity. It further supports the idea of a brain plasticity potential in deaf and hearing people. The association between network organization and acquired sign language experience reflects the ability of ongoing brain adaptation in people with hearing disabilities.

Targeted next generation sequencing reveals OTOF mutations in auditory neuropathy spectrum disorder

OBJECTIVE

To study the genetic etiology of auditory neuropathy spectrum disorder (ANSD) in a Chinese family and perform a literature review of OTOF mutations and cochlear implantation (CI).

METHODS

Sequential targeted next generation sequencing (NGS) and CI was performed for the proband. Further, 50 DNA samples from unrelated families with nonsyndromic deafness were examined for frequency determination. The impact of OTOF mutations on hearing recovery after CI was assessed through the literature survey.

RESULTS

In the proband, the targeted NGS panel revealed five suspected variants in four genes (OTOF, EYA4, PCDH15, and GIPC3), of which two mutations-c.5098G > C (p.Glu1700Gln) and c.1702C > T (p.Arg568Trp)-in the OTOF gene were found to be correlated with ANSD. The c.5098G > C allele was identified in only one child from the 50 unrelated participants. The proband's hearing and speech abilities were restored 2 years after the surgery. Most ANSD patients (90.9%; 30/33) with OTOF mutations have acceptable surgical outcomes, as indicated by existing reports.

CONCLUSIONS

Our results support the feasibility of CI for patients with ANSD and OTOF mutations, and this hypothesis was supported by the review of existing data. A larger number of cases studies is required to determine possible modifies on the prognosis of surgery.

An unusual case of post-cochlear implant performance degradation in a patient with suspected Cogan's syndrome

Cogan's Syndrome is an autoimmune disorder that can affect the ear, eye and other organs. Although rare, Cogan's Syndrome is particularly relevant to the cochlear implant surgeon because the resulting hearing loss is often bilateral and the majority of cases progresses to profound levels where cochlear implantation may be indicated. There are many issues relating to this condition that concern the cochlear implant surgeon. Its rarity, lack of specific laboratory diagnostic tests and variability in the onset and types of manifestation relating to the ear, eye and other organs often pose diagnostic difficulties. Pre-operatively, the cochlear implant surgeon must anticipate and exclude the possibility of cochlear luminal obliteration and ossification. Although the post-implant hearing results are expected to be generally good in Cogan's Syndrome, the possibility of adverse hearing outcomes cannot be ruled out whether in the initial or subsequent post-operative period. The possible side effects of long-term immuno-suppressive therapy on the well-being of the cochlear implant are to be appreciated and managed. A case which posed much difficulty in management is presented and discussed to highlight some of these challenges.

LHFPL5 mutation: A rare cause of non-syndromic autosomal recessive hearing loss

Hearing loss is a debilitating disorder that impairs language acquisition, resulting in disability in children and potential isolation in adulthood. Its onset can have a genetic basis, though environmental factors, which are often preventable, can also cause the condition. The genetic forms are highly heterogeneous, and early detection is necessary to arrange appropriate patient support. Here we report the molecular basis of hereditary hearing loss in a consanguineous family with multiple affected members from Oman. Combining homozygosity mapping with whole exome sequencing identified a novel homozygous nucleotide substitution c.575T > C in the lipoma HMGIC fusion partner-like 5 gene (LHFPL5), that converted the 192^nd amino acid residue in the protein from a leucine to a proline, p.(Leu192Pro). Sanger sequencing confirmed segregation with the disease phenotype as expected for a recessive condition and the variant was absent in 123,490 subjects from various disease-specific and population genetic studies as well as 150 unrelated individuals and 35 deaf patients of Omani ethnicity. This study, which describes a novel LHFPL5 mutation in a family of Omani origin with hereditary hearing loss, supports previous clinical descriptions of the condition and contributes to the genetic spectrum of mutations in this form of deafness.

A spontaneous mouse deletion in Mctp1 uncovers a long-range cis-regulatory region crucial for NR2F1 function during inner ear development

Hundreds of thousands of cis-regulatory DNA sequences are predicted in vertebrate genomes, but unlike genes themselves, few have been characterized at the functional level or even unambiguously paired with a target gene. Here we serendipitously identified and started investigating the first reported long-range regulatory region for the Nr2f1 (Coup-TFI) transcription factor gene. NR2F1 is temporally and spatially regulated during development and required for patterning and regionalization in the nervous system, including sensory hair cell organization in the auditory epithelium of the cochlea. Analyzing the deaf wanderer (dwnd) spontaneous mouse mutation, we traced back the cause of its associated circling behavior to a 53 kb deletion removing five exons and adjacent intronic regions of the poorly characterized Mctp1 gene. Interestingly, loss of Mctp1 function cannot account for the hearing loss, inner ear dysmorphology and sensory hair cell disorganization observed in dwnd mutants. Instead, we found that the Mctp1dwnd deletion affects the Nr2f1 gene located 1.4 Mb away, downregulating transcription and protein expression in the embryonic cochlea. Remarkably, the Mctp1dwnd allele failed to complement a targeted inactivation allele of Nr2f1, and transheterozygotes or Mctp1dwnd homozygotes exhibit the same morphological defects observed in inner ears of Nr2f1 mutants without sharing their early life lethality. Defects include improper separation of the utricle and saccule in the vestibule not described previously, which can explain the circling behavior that first brought the spontaneous mutation to attention. By contrast, mice homozygous for a targeted inactivation of Mctp1 have normal hearing and inner ear structures. We conclude that the 53 kb Mctp1dwnd deletion encompasses a long-range cis-regulatory region essential for proper Nr2f1 expression in the embryonic inner ear, providing a first opportunity to investigate Nr2f1 function in postnatal inner ears. This work adds to the short list of long-range regulatory regions characterized as essential to drive expression of key developmental control genes.