GJB2 Gene Mutations in Syndromic Skin Diseases with Sensorineural Hearing Loss.

The GJB2 gene is located on chromosome 13q12 and it encodes the connexin 26, a transmembrane protein involved in cell-cell attachment of almost all tissues. GJB2 mutations cause autosomal recessive (DFNB1) and sometimes dominant (DFNA3) non-syndromic sensorineural hearing loss. Moreover, it has been demonstrated that connexins are involved in regulation of growth and differentiation of epidermis and, in fact, GJB2 mutations have also been identified in syndromic disorders with hearing loss associated with various skin disease phenotypes. GJB2 mutations associated with skin disease are, in general, transmitted with a dominant inheritance pattern. Nonsyndromic deafness is caused prevalently by a loss-of-function, while literature evidences suggest for syndromic deafness a mechanism based on gain-of-function. The spectrum of skin manifestations associated with some mutations seems to have a very high phenotypic variability. Why some mutations can lead to widely varying cutaneous manifestations is poorly understood and in particular, the reason why the skin disease-deafness phenotypes differ from each other thus remains unclear. This review provides an overview of recent findings concerning pathogenesis of syndromic deafness imputable to GJB2 mutations with an emphasis on relevant clinical genotype-phenotype correlations. After describing connexin 26 fundamental characteristics, the most relevant and recent information about its known mutations involved in the syndromic forms causing hearing loss and skin problems are summarized. The possible effects of the mutations on channel expression and function are discussed

Audio-Vestibular Alterations During the Phases of the Menstrual Cycle in Patients with Cochlear Implant

Background: The female hormones fluctuations in woman’s life play a dominant role in homeostasis of the body and can influence the psycho-neurological processes in different body systems. In particular, in the auditory system seems that hormonal alterations during the menstrual cycle can compromise the homeostasis of the labyrinthine fluids altering balance and/or hearing. Aims/Objectives: Our study aims to verify if hormonal changes during different menstrual phases may have an influence, in females with cochlear implants, on the trend of auditory and vestibular performances. Materials and methods: Tonal, speech audiometry, vestibular examination and a measure of cochlear implants electrodes impedances were realized in the follicular and luteal phases on a group of eight women who are at a fertile age, affected by profound sensorineural form of hearing loss and carrying a monolateral cochlear implant. Results: Audio-vestibular alterations, as well as, an increase of impedance electrodes are reported in the luteal phase. Conclusions: Our work suggests that audio-vestibular alterations are related to the different phases of the menstrual cycle with consequent variation also of the performances of the implant. It is very important to keep in mind this aspect to avoid negative results during rehabilitation