Multicentric Longitudinal Prospective Study in a European Cohort of MYO7A Patients: Disease Course and Implications for Gene Therapy.

Purpose: We investigated the natural history of retinal dystrophy owing to variants in the MYO7A gene. Methods: Fifty-three patients (mean age, 33.6 ± 16.7 years) with Usher syndrome owing to biallelic, mostly pathogenic, variants in MYO7A underwent baseline and two annual follow-up visits. Best-corrected visual acuity (BCVA), semiautomatic kinetic visual field, full-field electroretinogram, color fundus imaging, microperimetry, spectral-domain optical coherence tomography, and fundus autofluorescence were assessed. Results: At baseline, all patients presented with decreased BCVA (66.4 ± 17.9 Early Treatment Diabetic Retinopathy score and 59.5 ± 21.7 Early Treatment Diabetic Retinopathy score, in the better- and worse-seeing eyes, respectively), restricted semiautomatic kinetic visual field (III4e area, 3365.8 ± 4142.1°2; 4176.4 ± 4400.3°2) and decreased macular sensitivity (9.7 ± 9.9 dB; 9.0 ± 10.2 dB). Spectral-domain optical coherence tomography revealed reduced central macular thickness (259.6 ± 63.0 µm; 250.7 ± 63.3 µm) and narrowed ellipsoid zone band width (2807.5 ± 2374.6 µm; 2615.5 ± 2370.4 µm). Longitudinal analyses (50 patients) showed a significant decrease of BCVA in better-seeing eyes, whereas no changes were observed in worse-seeing eyes for any parameter. BCVA, semiautomatic kinetic visual field (III4e and V4e) and macular sensitivity were related significantly to age at baseline. Hyperautofluorescent foveal patch (16 eyes [31.4%]) and abnormal central hypoautofluorescence (9 eyes [17.6%]) were significantly associated with worse morphological and functional read-outs compared with the hyperautofluorescent ring pattern (22 eyes [43.1%]). Conclusions: Our European multicentric study offers the first prospective longitudinal analysis in one of the largest cohorts of MYO7A patients described to date, confirming the slow disease progression. More important, this study emphasizes the key role of fundus autofluorescence patterns in retinal impairment staging and advocates its adoption as an objective biomarker in patient selection for future gene therapy clinical trials.

The natural history and genotype-phenotype correlations of TMPRSS3 hearing loss: an international, multi-center, cohort analysis.

TMPRSS3-related hearing loss presents challenges in correlating genotypic variants with clinical phenotypes due to the small sample sizes of previous studies. We conducted a cross-sectional genomics study coupled with retrospective clinical phenotype analysis on 127 individuals. These individuals were from 16 academic medical centers across 6 countries. Key findings revealed 47 unique TMPRSS3 variants with significant differences in hearing thresholds between those with missense variants versus those with loss-of-function genotypes. The hearing loss progression rate for the DFNB8 subtype was 0.3 dB/year. Post-cochlear implantation, an average word recognition score of 76% was observed. Of the 51 individuals with two missense variants, 10 had DFNB10 with profound hearing loss. These 10 all had at least one of 4 TMPRSS3 variants predicted by computational modeling to be damaging to TMPRSS3 structure and function. To our knowledge, this is the largest study of TMPRSS3 genotype-phenotype correlations. We find significant differences in hearing thresholds, hearing loss progression, and age of presentation, by TMPRSS3 genotype and protein domain affected. Most individuals with TMPRSS3 variants perform well on speech recognition tests after cochlear implant, however increased age at implant is associated with worse outcomes. These findings provide insight for genetic counseling and the on-going design of novel therapeutic approaches.

Long-Term Outcomes of a Percutaneous Wide-Diameter Bone-Anchored Hearing Implant: A Clinical Evaluation of More than 800 Implants.

OBJECTIVE: This study evaluates the clinical outcomes of 807 percutaneous wide-diameter bone-anchored hearing implants (BAHIs) in 701 patients. In addition, it compares patient groups and examines bone conduction device (BCD) usage. STUDY DESIGN: Retrospective cohort study. Mean follow-up period of 3.8 years. SETTING: Tertiary referral center. PATIENTS: All patients implanted with a percutaneous wide-diameter BAHI until December 2020 were included. Patients were divided into age groups, "loading-time" groups, and, if applicable, specific subgroups thought to be at risk for complications postsurgery, e.g., intellectual disability and comorbidities. MAIN OUTCOME MEASURES: Soft tissue reaction, implant survival, revision surgery, and BCD usage. RESULTS: In 9.1% of the 5,188 observations of 807 implants, an adverse soft tissue reaction was reported according to the Holgers' scale. Significantly more (adverse) soft tissue reactions were observed in children and intellectually disabled (ID) patients (p < 0.05). Comorbidity subgroups showed no significant differences in soft tissue reactions. Implant loss percentage, including explantations, was 6.2%. Implant survival was significantly worse in patients with ID (14.1%; p = 0.021). Pediatric age, early loading, or comorbidities did not significantly influence implant survival. At least 592 implants (73.4%) were used for bone conduction hearing, of which 65.4% were used daily. CONCLUSION: Both children and ID patients are more prone to (adverse) soft tissue reactions, ID patients only have a higher risk of implant loss. The rate of implant loss in children seemed to be reduced compared to previous studies and thus more comparable to adults since using wide-diameter implants.

Surgical Treatment for Troublesome Mastoid Cavities: Canal Wall Reconstruction With Bony Obliteration Versus Subtotal Petrosectomy.

INTRODUCTION: A chronically discharging modified radical mastoid cavity may require surgical intervention. We aim to explore two techniques. OBJECTIVE: To compare outcomes of subtotal petrosectomy (STP) and canal wall reconstruction with bony obliteration technique (CWR-BOT). STUDY DESIGN: Retrospective cohort study. SETTING: A tertiary referral center. PATIENTS: All patients with a chronically discharging mastoid cavity surgically treated at the Radboud University Medical Center by STP or CWR-BOT in 2015 to 2020, excluding patients with preoperative cholesteatoma. MAIN OUTCOME MEASURES: Dry ear rate, audiometry, and rehabilitation. SECONDARY OUTCOME MEASURES: Healing time, number of postoperative visits, complications, cholesteatoma, and need for revision surgeries. RESULTS: Thirty-four (58%) patients underwent STP, and 25 (42%) CWR-BOT. A dry ear was established in 100% of patients (STP) and 87% (CWR-BOT). The air-bone gap (ABG) increased by 12 dB in STP, and decreased by 11 dB in CWR-BOT. Postoperative ABG of CWR-BOT patients was better when preoperative computed tomography imaging showed aerated middle ear aeration. ABG improvement was higher when ossicular chain reconstruction took place. Mean follow-up time was 32.5 months (STP) versus 40.5 months (CWR-BOT). Healing time was 1.2 months (STP) versus 4.1 months (CWR-BOT). The number of postoperative visits was 2.5 (STP) versus 5 (CWR-BOT). Cholesteatoma was found in 15% (STP) versus 4% (CWR-BOT) of patients. Complication rate was 18% (STP) and 24% (CWR-BOT) with a need for revision in 21% (STP) and 8% (CWR-BOT), including revisions for cholesteatoma. CONCLUSION: STP and CWR-BOT are excellent treatment options for obtaining a dry ear in patients with a chronically discharging mastoid cavity. This article outlines essential contributing factors in counseling patients when opting for one or the other. Magnetic resonance imaging with diffusion-weighted imaging follow-up should be conducted at 3 and 5 years postoperatively.

Cochlear supporting cells require GAS2 for cytoskeletal architecture and hearing.

In mammals, sound is detected by mechanosensory hair cells that are activated in response to vibrations at frequency-dependent positions along the cochlear duct. We demonstrate that inner ear supporting cells provide a structural framework for transmitting sound energy through the cochlear partition. Humans and mice with mutations in GAS2, encoding a cytoskeletal regulatory protein, exhibit hearing loss due to disorganization and destabilization of microtubule bundles in pillar and Deiters' cells, two types of inner ear supporting cells with unique cytoskeletal specializations. Failure to maintain microtubule bundle integrity reduced supporting cell stiffness, which in turn altered cochlear micromechanics in Gas2 mutants. Vibratory responses to sound were measured in cochleae from live mice, revealing defects in the propagation and amplification of the traveling wave in Gas2 mutants. We propose that the microtubule bundling activity of GAS2 imparts supporting cells with mechanical properties for transmitting sound energy through the cochlea.

Hearing Results of Surgery for Acquired Atresia of the External Auditory Canal.

OBJECTIVE: To evaluate short- and long-term hearing results of surgery for acquired atresia of the external auditory canal (EAC) in a large patient cohort and to define preoperative audiometric conditions useful for patient counseling. STUDY DESIGN: Retrospective cohort study. SETTING: Academic tertiary referral center. PATIENTS: Seventy-eight ears from 72 patients with postinflammatory acquired atresia of the EAC who underwent canal- and meatoplasty were included. Patients with involvement of the ossicular chain, (syndromic) external ear malformations, or congenital aural atresia were excluded. INTERVENTION: Canal- and meatoplasty. MAIN OUTCOME MEASURES: Mean pure-tone averages of thresholds at 0.5, 1, 2, and 3 kHz (PTA0.5,1,2,3) for air conduction (AC), bone conduction, and air-bone gap (ABG) were calculated preoperatively and at short-term (≤0.55 yr) and long-term follow-up (>0.55 yr). Additionally, the numbers of ears with a closed ABG ≤10 dB and ≤20 dB, and with Social hearing (defined as: AC PTA0.5,1,2,3 ≤35 dB) were assessed. RESULTS: At short-term follow-up AC PTA0.5,1,2,3 improved by 18 dB. Social hearing was obtained in 81% of the ears. Postoperatively, 35% of the ears had a closed ABG ≤10 dB, 83% was closed ≤20 dB. During follow-up, significant deterioration of 5 to 7 dB occurred for AC thresholds at 0.25, 0.5, and 1 kHz. CONCLUSIONS: Surgery for acquired atresia of the EAC is often beneficial. This study suggests overall advantageous surgery when the preoperative indication criteria ABG PTA0.5,1,2,3 >20 dB and AC PTA0.5,1,2,3 >35 dB are applied.

De novo and inherited loss-of-function variants of ATP2B2 are associated with rapidly progressive hearing impairment.

ATP2B2 encodes the PMCA2 Ca2+ pump that plays an important role in maintaining ion homeostasis in hair cells among others by extrusion of Ca2+ from the stereocilia to the endolymph. Several mouse models have been described for this gene; mice heterozygous for loss-of-function defects display a rapidly progressive high-frequency hearing impairment. Up to now ATP2B2 has only been reported as a modifier, or in a digenic mechanism with CDH23 for hearing impairment in humans. Whole exome sequencing in hearing impaired index cases of Dutch and Polish origins revealed five novel heterozygous (predicted to be) loss-of-function variants of ATP2B2. Two variants, c.1963G>T (p.Glu655*) and c.955delG (p.Ala319fs), occurred de novo. Three variants c.397+1G>A (p.?), c.1998C>A (p.Cys666*), and c.2329C>T (p.Arg777*), were identified in families with an autosomal dominant inheritance pattern of hearing impairment. After normal newborn hearing screening, a rapidly progressive high-frequency hearing impairment was diagnosed at the age of about 3-6 years. Subjects had no balance complaints and vestibular testing did not yield abnormalities. There was no evidence for retrocochlear pathology or structural inner ear abnormalities. Although a digenic inheritance pattern of hearing impairment has been reported for heterozygous missense variants of ATP2B2 and CDH23, our findings indicate a monogenic cause of hearing impairment in cases with loss-of-function variants of ATP2B2.

Risk factors for complications in cochlear implant surgery.

PURPOSE: The objective of this study was to achieve uniform reporting of complications and failures in cochlear implantation, to analyze complications and failures and to identify risk factors for complications in a series of over 1300 cochlear implantations. METHODS: In a retrospective chart review and observational study, data from all cochlear implantations from 1987 to 2015 were entered in a custom-made database. Complications were classified using the contracted form of the Clavien-Dindo system and risk factors were identified by statistical analysis. RESULTS: A complication rate of 18.4% and a device failure rate of 2.9% were found. There was a higher rate of hematoma in patients with a clotting disorder and when a subtotal petrosectomy was performed, a higher rate of wound infections in patients who were not vaccinated against Streptococcus pneumoniae and a higher rate of meningitis in patients with an inner ear malformation. CONCLUSIONS: The use of a strict definition of a medical complication and device failure-in combination with the Clavien-Dindo classification system-enables uniform and objective registration of adverse events and prevents any tendency to downgrade complications. Complication and failure rates in this series are comparable to those reported in the literature. These results stress the need for pneumococcal vaccination, which may prevent general wound infections, but is especially important for patients with inner ear malformation, who have an increased risk of (postoperative) meningitis.

The diagnostic yield of whole-exome sequencing targeting a gene panel for hearing impairment in The Netherlands.

Hearing impairment (HI) is genetically heterogeneous which hampers genetic counseling and molecular diagnosis. Testing of several single HI-related genes is laborious and expensive. In this study, we evaluate the diagnostic utility of whole-exome sequencing (WES) targeting a panel of HI-related genes. Two hundred index patients, mostly of Dutch origin, with presumed hereditary HI underwent WES followed by targeted analysis of an HI gene panel of 120 genes. We found causative variants underlying the HI in 67 of 200 patients (33.5%). Eight of these patients have a large homozygous deletion involving STRC, OTOA or USH2A, which could only be identified by copy number variation detection. Variants of uncertain significance were found in 10 patients (5.0%). In the remaining 123 cases, no potentially causative variants were detected (61.5%). In our patient cohort, causative variants in GJB2, USH2A, MYO15A and STRC, and in MYO6 were the leading causes for autosomal recessive and dominant HI, respectively. Segregation analysis and functional analyses of variants of uncertain significance will probably further increase the diagnostic yield of WES.

TSHZ1-dependent gene regulation is essential for olfactory bulb development and olfaction.

The olfactory bulb (OB) receives odor information from the olfactory epithelium and relays this to the olfactory cortex. Using a mouse model, we found that development and maturation of OB interneurons depends on the zinc finger homeodomain factor teashirt zinc finger family member 1 (TSHZ1). In mice lacking TSHZ1, neuroblasts exhibited a normal tangential migration to the OB; however, upon arrival to the OB, the neuroblasts were distributed aberrantly within the radial dimension, and many immature neuroblasts failed to exit the rostral migratory stream. Conditional deletion of Tshz1 in mice resulted in OB hypoplasia and severe olfactory deficits. We therefore investigated olfaction in human subjects from families with congenital aural atresia that were heterozygous for TSHZ1 loss-of-function mutations. These individuals displayed hyposmia, which is characterized by impaired odor discrimination and reduced olfactory sensitivity. Microarray analysis, in situ hybridization, and ChIP revealed that TSHZ1 bound to and regulated expression of the gene encoding prokineticin receptor 2 (PROKR2), a G protein­coupled receptor essential for OB development. Mutations in PROKR2 lead to Kallmann syndrome, characterized by anosmia and hypogonadotrophic hypogonadism. Our data indicate that TSHZ1 is a key regulator of mammalian OB development and function and controls the expression of molecules involved in human Kallmann syndrome.

A new bone-anchored hearing implant: short-term retrospective data on implant survival and subjective benefit.

This report provides the first short-term follow-up data on the Ponto bone-anchored hearing implant from our tertiary referral centre. Thirty-one consecutive patients with a mean age of 51 years who received the implant between October 2010 and December 2011 were included retrospectively in this study. Implant loss, skin reactions around the implant (according to Holgers' grading system), revision surgery, and abutment replacements were retrospectively gathered from the patients' files as objective outcome measures. To obtain information on subjective patient satisfaction, the Glasgow Benefit Inventory (GBI) was used. The mean follow-up period was 16.9 months (range 12.1-25.2 months). One implant was lost. Over a total of 94 follow-up visits, 21 skin reactions were observed in 16 patients: Holgers grade 1 (slight redness, no need for treatment) in 18.1 % of the visits,and grade 2 (redness and moist, needing conservative treatment) in 4.3 % of the visits. Four 6-mm abutments (12.9 %) were replaced for a 9-mm abutment during the follow-up period, of which one (3.2 %) was in combination with revision surgery. In one patient keloid formation around the implant was observed. The GBI revealed a moderate subjective benefit. The short-term results with these percutaneous implants demonstrate a clinically stable implant with a low percentage of skin reactions that require treatment. Long-term, prospective follow-up data are needed to draw firmer conclusions.

Cervical dystonia after ear surgery.

BACKGROUND: The pathophysiology of primary focal dystonia remains insufficiently understood, but may be explained by a 'double-lesion' model, in which a particular trigger on top of an intrinsic susceptibility due to a certain genetic predisposition can induce dystonia. CASE-REPORT: Here, we describe a patient who developed cervical dystonia soon after ear surgery (revision stapedectomy), which had caused vestibular hypofunction. DISCUSSION: We also discuss other cases of dystonia associated with vestibular lesions and with other reported triggers, and put these into the context of the possible pathophysiology.

Genotype-phenotype correlation in DFNB8/10 families with TMPRSS3 mutations.

In the present study, genotype-phenotype correlations in eight Dutch DFNB8/10 families with compound heterozygous mutations in TMPRSS3 were addressed. We compared the phenotypes of the families by focusing on the mutation data. The compound heterozygous variants in the TMPRSS3 gene in the present families included one novel variant, p.Val199Met, and four previously described pathogenic variants, p.Ala306Thr, p.Thr70fs, p.Ala138Glu, and p.Cys107Xfs. In addition, the p.Ala426Thr variant, which had previously been reported as a possible polymorphism, was found in one family. All affected family members reported progressive bilateral hearing impairment, with variable onset ages and progression rates. In general, the hearing impairment affected the high frequencies first, and sooner or later, depending on the mutation, the low frequencies started to deteriorate, which eventually resulted in a flat audiogram configuration. The ski-slope audiogram configuration is suggestive for the involvement of TMPRSS3. Our data suggest that not only the protein truncating mutation p.T70fs has a severe effect but also the amino acid substitutions p.Ala306Thr and p.Val199Met. A combination of two of these three mutations causes prelingual profound hearing impairment. However, in combination with the p.Ala426Thr or p.Ala138Glu mutations, a milder phenotype with postlingual onset of the hearing impairment is seen. Therefore, the latter mutations are likely to be less detrimental for protein function. Further studies are needed to distinguish possible phenotypic differences between different TMPRSS3 mutations. Evaluation of performance of patients with a cochlear implant indicated that this is a good treatment option for patients with TMPRSS3 mutations as satisfactory speech reception was reached after implantation.

Natural history of hearing deterioration in intracanalicular vestibular schwannoma.

BACKGROUND: Intracanalicular vestibular schwannomas have a range of treatment options that can preserve hearing: microsurgery, stereotactic radiotherapy, and conservative observation. OBJECTIVE: To evaluate the natural course of hearing deterioration during a period of conservative observation. METHODS: A retrospective case review was performed on 47 patients with a unilateral intracanalicular vestibular schwannoma. Evaluation of growth was monitored by repeat MRI scanning. Repeated pure-tone and speech audiometry results were evaluated for subgroups of patients showing growth or no growth and by subsite location of tumor in the internal auditory canal. RESULTS: Patients had a mean follow-up of 3.6 years. Over the entire population, the pure-tone average thresholds at 0.5, 1, 2, and 3 kHz and the word recognition scores both significantly deteriorated from 38 to 51 dB HL, and from 66% to 55%, respectively. Overall, 74% of subjects with good hearing, according to the 50/50 rule, maintained hearing above this rule. There were no significant differences in hearing loss by subsite in the internal auditory canal (porus, fundus, central) or by growth status (stable, growing, shrinking). Only 6 patients showed a large hearing change. This happened early during follow-up, with relatively stable hearing after this. CONCLUSION: Hearing will deteriorate in some intracanalicular vestibular schwannomas, regardless of tumor growth. Hearing deterioration, if on a large scale, most likely occurs early in follow-up. The present results using conservative management in these tumors appear similar to those reported for stereotactic radiotherapy or microsurgery.

Simple mass loading of the tympanic membrane to alleviate symptoms of patulous eustachian tube.

BACKGROUND: Patulous eustachian tube (PET) has a major impact on a patient's quality of life. The purpose of this study was to understand mechanisms behind the symptoms, develop treatments based on these, and develop and use a questionnaire to measure changes in PET symptoms with a novel intervention. Our hypothesis is that PET symptoms can be addressed at the level of the eardrum more easily than at the level of the eustachian tube. METHODS: In a population of 14 PET subjects and 6 fresh temporal bones, several investigations were performed. Nasal audiometry was used to measure frequencies preferentially transmitted to the ear in PET subjects. An intervention consisting of mass loading of the eardrum was devised in the temporal bones to damp these frequencies. This was then applied to subjects with PET. A questionnaire was developed and administered to measure the response to this intervention. This questionnaire included the more common symptoms associated with PET, such as echoing sounds, increased environmental sounds, and a plugging sensation in the ear. Mass loading of the eardrum was performed with Blu Tack, a clay-like, nontoxic substance. RESULTS/CONCLUSION: Low frequencies are preferentially transmitted in PET, and eardrum vibrations to these can be mitigated with mass loading. Mass loading in human subjects significantly reduced major symptoms of PET, although temporarily.

Postauricular approach atticotomy: a modified closed technique with reconstruction of the scutum with cymbal cartilage.

OBJECTIVES: We studied the results of postauricular approach atticotomy in patients with cholesteatoma of the anterior epitympanum. METHODS: Twenty-six patients were selected for removal of cholesteatoma of the anterior epitympanum by postauricular approach atticotomy, a closed transcanal procedure that is used to expose and remove cholesteatoma. After removal of cholesteatoma, reconstruction of the scutum is performed with cymbal cartilage. RESULTS: Postauricular approach atticotomy can be performed as part of a canal wall-up procedure in selected cases in which cholesteatoma invades the anterior epitympanum. Especially if the ossicular chain is intact and if there is an anteriorly curved medial outer canal wall, this technique is useful in avoiding an open technique. A second-look procedure is recommended because of a relatively high percentage of recurrent and residual disease. CONCLUSIONS: Postauricular approach atticotomy with reconstruction of the scutum is a useful technique to remove cholesteatoma from the anterior epitympanum.

Efficacy of diagnostic upper node evaluation during (salvage) laryngectomy for supraglottic carcinoma.

BACKGROUND: The effectiveness of selective upper node dissection or inspection during laryngectomy for supraglottic squamous cell carcinoma was evaluated. These diagnostic procedures aimed to cause less morbidity than elective neck dissection in patients with a clinically N0 neck. METHODS: In 93 patients, 166 clinically N0 necks (73 bilateral and 20 contralateral) were evaluated. Lymph nodes at levels II and III were inspected or dissected and directly sent in for frozen section histopathology. This way, occult neck metastases were identified and treated by neck dissection. RESULTS: Occult neck metastases were identified in 19% of the examined necks (31/166). Regional recurrence rate in the postoperative N0 necks was 0%, and 10% in the postoperative N+ necks. CONCLUSIONS: Selective upper node dissection and inspection during laryngectomy reduced the need for an elective neck dissection with its morbidity in the clinically N0 neck. In addition, it selects the patients who need such extensive treatment.

Efficacy of diagnostic upper-node procedures during laryngectomy for glottic carcinoma.

BACKGROUND: Regional recurrence of glottic squamous cell carcinoma was evaluated in patients with a clinically N0 neck who underwent selective upper-node dissection (SUND) or selective upper-node inspection (SUNI; surgical visualization and palpation of jugular lymph nodes at levels II and III) during (salvage) laryngectomy. METHODS: In 152 patients, 291 clinically N0 (139 bilateral and 13 contralateral) necks were evaluated for occult neck metastases by SUNI or SUND during (salvage) laryngectomy. RESULTS: Occult neck metastases were identified with SUNI or SUND in 7% of the necks (21 of 291). In 4% (n = 11) of the remaining 270 necks, regional recurrence was detected during follow-up evaluation. Thus, in these 8 patients, SUNI or SUND seemed to have failed. CONCLUSIONS: SUND or SUNI of levels II and III during (salvage) laryngectomy identified the vast majority of patients who needed extensive neck treatment. In the N0 necks, these techniques led to less morbidity than elective neck dissection.

Cochleovestibular and ocular features in a Dutch DFNA11 family.

OBJECTIVES: To report hearing impairment and vestibular and ocular features in a Dutch DFNA11 family and to compare these results to reported data on three other DFNA11 families. STUDY DESIGN: Family study. METHODS: Regression analysis was performed in relation to age to outline the development of hearing thresholds and speech recognition scores. Vestibular and ocular functions were examined. RESULTS: First symptoms of hearing impairment started between the ages of 4 and 43 years. Most of the audiograms were symmetric and flat or downsloping. The annual threshold deterioration increased from 0.2 to 2.6 dB per year at 0.25 to 8 kHz in the longitudinal analyses and in the cross-sectional analysis from 0.3 to 0.9 dB per year. The speech recognition score was quite good, deteriorating by 0.9% per year from a 90% score at the age of 36 years onward. Remarkably, extensive ocular examination including corrected visual acuity and refraction measurements, slit-lamp examination, ophthalmoscopy, Goldmann perimetry, electroretinography and electro-oculography revealed signs of subclinical retinal dysfunction. None of the patients showed the classic triad of retinitis pigmentosa. Pure-tone thresholds, phoneme recognition scores, and vestibular responses of the mutation carriers were fairly similar to previously described DFNA11 families. CONCLUSION: Even though the diverse mutations are located in different regions of the myosin VIIa gene, the cochleovestibular phenotype is fairly similar in all DFNA11 families. Surprisingly, only in this family was subclinical retinal dysfunction detected.

Identification and molecular modelling of a mutation in the motor head domain of myosin VIIA in a family with autosomal dominant hearing impairment (DFNA11).

Myosin VIIA is an unconventional myosin that has been implicated in Usher syndrome type 1B, atypical Usher syndrome, non-syndromic autosomal recessive hearing impairment (DFNB2) and autosomal dominant hearing impairment (DFNA11). Here, we present a family with non-syndromic autosomal dominant hearing impairment that clinically resembles the previously published DFNA11 family. The affected family members show a flat audiogram at young ages and only modest progression, most clearly at the high frequencies. In addition, they suffer from minor vestibular symptoms. Linkage analysis yielded a maximum two-point lodscore of 3.43 for marker D11S937 located within 1 cM of the myosin VIIA gene. The myosin VIIA gene was sequenced and 11 nucleotide variations were found. Ten nucleotide changes represent benign intronic variants, silent exon mutations or non-pathologic amino acid substitutions. One variant, a c.1373A-->T transversion that is heterozygously present in all affected family members and absent in 300 healthy individuals, is predicted to result in an Asn458Ile amino acid substitution. Asn458 is located in a region of the myosin VIIA motor domain that is highly conserved in different classes of myosins and in myosins of different species. To evaluate whether the Asn458Ile mutation was indeed responsible for the hearing impairment, a molecular model of myosin VIIA was built based on the known structure of the myosin II heavy chain from Dictyostelium discoideum. In this model, conformational changes in the protein caused by the amino acid substitution Asn458Ile are predicted to disrupt ATP/ADP binding and impair the myosin power-stroke, which would have a severe effect on the function of the myosin VIIA protein.