Gene Expression Profiles of the Cochlea and Vestibular Endorgans: Localization and Function of Genes Causing Deafness

Objectives: We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. Methods: Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Honnepage using localization, expression, and distribution as keywords. Results: Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. Conclusions: The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.ArticleANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY. 124:6S-48S (2015)journal articl

Comprehensive Genetic Analysis of Japanese Autosomal Dominant Sensorineural Hearing Loss Patients.

In general, autosomal dominant inherited hearing loss does not have a founder mutation, with the causative mutation different in each family. For this reason, there has been a strong need for efficient diagnosis methods for autosomal dominant sensorineural hearing loss (ADSNHL) patients. This study sought to verify the effectiveness of our analysis algorithm for the screening of ADSNHL patients as well as the usefulness of the massively parallel DNA sequencing (MPS).Seventy-five Japanese ADSNHL patients from 53 ENT departments nationwide participated in this study. We conducted genetic analysis of 75 ADSNHL patients using the Invader assay, TaqMan genotyping assay and MPS-based genetic screening.A total of 46 (61.3%) ADSNHL patients were found to have at least one candidate gene variant.We were able to achieve a high mutation detection rate through the combination of the Invader assay, TaqMan genotyping assay and MPS. MPS could be used to successfully identify mutations in rare deafness genes

The overview of our analysis algorithm using 3-step genetic analysis (Invader assay, TaqMan genotyping assay and MPS).

<p>The overview of our analysis algorithm using 3-step genetic analysis (Invader assay, TaqMan genotyping assay and MPS).</p

The mutations found by the 3^rd screening in this study.

<p>The mutations found by the 3^rd screening in this study.</p

The mutations found by the 1^st and 2^nd screenings in this study.

<p>The mutations found by the 1^st and 2^nd screenings in this study.</p

Deafness gene expression patterns in the mouse cochlea found by microarray analysis.

Tonotopy is one of the most fundamental principles of auditory function. While gradients in various morphological and physiological characteristics of the cochlea have been reported, little information is available on gradient patterns of gene expression. In addition, the audiograms in autosomal dominant non syndromic hearing loss can be distinctive, however, the mechanism that accounts for that has not been clarified. We thought that it is possible that tonotopic gradients of gene expression within the cochlea account for the distinct audiograms.We compared expression profiles of genes in the cochlea between the apical, middle, and basal turns of the mouse cochlea by microarray technology and quantitative RT-PCR. Of 24,547 genes, 783 annotated genes expressed more than 2-fold. The most remarkable finding was a gradient of gene expression changes in four genes (Pou4f3, Slc17a8, Tmc1, and Crym) whose mutations cause autosomal dominant deafness. Expression of these genes was greater in the apex than in the base. Interestingly, expression of the Emilin-2 and Tectb genes, which may have crucial roles in the cochlea, was also greater in the apex than in the base.This study provides baseline data of gradient gene expression in the cochlea. Especially for genes whose mutations cause autosomal dominant non syndromic hearing loss (Pou4f3, Slc17a8, Tmc1, and Crym) as well as genes important for cochlear function (Emilin-2 and Tectb), gradual expression changes may help to explain the various pathological conditions

Bilateral delayed endolymphatic hydrops evaluated by bilateral intratympanic injection of gadodiamide with 3T-MRI.

The purpose of this study was to assess the diagnostic performance of 3T MRI after intratympanic injection of gadodiamide for delayed endolymphatic hydrops (DEH), and assess the relationship between endolymphatic hydrops (ELH) and vestibular function in patients diagnosed with DEH and confirmed by 3T MRI. Nineteen patients clinically diagnosed with DEH (11 ipsilateral DEH, 8 contralateral DEH) participated in this study. Diluted gadodiamide was administered to the bilateral tympanic cavity by injection through the tympanic membrane. At 24 hours post-injection, the ELH was evaluated by MRI. Patient vestibular functions were evaluated by caloric testing and cVEMP. ELH was observed in all patients (19/19: positive rate 100%). The distribution patterns of ELH varied between the cochlear or vestibular region. Vestibular ELH was observed in the affected ear in all ipsilateral DEH patients. In the contralateral DEH patients, however, there were individual differences in the distribution patterns of ELH. Six patients (1 ipsilateral DEH, 5 contralateral DEH) had bilateral ELH. No obvious relationships were observed between ELH and vestibular function. ELH distribution was complicated, particularly in the contralateral DEH cases. It was difficult to identify the existence of ELH by vestibular functional testing alone; therefore, 3T MRI is thought to be useful for identifying the affected ear. A significant number of cases had "bilateral" DEH, particularly among the contralateral DEH cases, indicating that we should pay careful attention to this pathology when treating DEH

The numbers of differentially expressed genes for apex vs. base, apex vs. middle, middle vs. base.

<p>The numbers of differentially expressed genes for apex vs. base, apex vs. middle, middle vs. base.</p

Microscopical image of the mouse cochlea (right ear).

<p>Bars indicate the incision points for each turn sample. A: apical turn, B: middle turn, C: basal turn, D: dissection example</p

Gene expression levels of corresponding genes for non syndromic hearing loss in each cochlea turn.

<p>Gene expression levels of corresponding genes for non syndromic hearing loss in each cochlea turn.</p