A number of ion channels and transporters are expressed in both the inner ear and kidney. In the inner ear, K(+) cycling and endolymphatic K(+), Na(+), Ca(2+), and pH homeostasis are critical for normal organ function. Ion channels and transporters involved in K(+) cycling include K(+) channels, Na(+)-2Cl(-)-K(+) cotransporter, Na(+)/K(+)-ATPase, Cl(-) channels, connexins, and K(+)/Cl(-) cotran...

Pendred syndrome (PS) is the second most common type of autosomal recessive syndromic hearing loss (HL). It is characterised by sensorineural HL and goiter with occasional hypothyroidism. These features are generally accompanied by malformations of the inner ear, as enlarged vestibular aqueduct (EVA). In about 50% of probands, mutations in the SLC26A4 gene are the cause of the disease. Here we ...

The objective is to describe the multidisciplinary management programme at the National University Hospital (NUH) in Singapore for children with hearing impairment (HI). Over 99.95% of babies born at NUH have hearing tested with both otoacoustic emission and automated auditory brainstem response tests by 6 weeks of age. The referral rate to Otolaryngology is 0.5%. Acquired causes of congenital ...

AIMS Mutations in the GJB2 gene-encoding connexin 26 protein are the main cause for autosomal recessive nonsyndromic hearing loss worldwide. In this study, we assessed the contributions made by GJB2 and del(GJB6-D13S1830) mutations to the autosomal recessive nonsyndromic deafness genetic load in Iranian Azeri Turkish patients. RESULTS Probands from 209 different nuclear families were investig...

The deafness locus DFNB1 contains GJB2, the gene encoding connexin26 and GJB6, encoding connexin30, which appear to be coordinately regulated in the inner ear. In this work, we investigated the expression and function of connexin26 and connexin30 from postnatal day 5 to adult age in double transgenic Cx26(Sox10Cre) mice, which we obtained by crossing connexin26 floxed mice with a deleter Sox10-...

Involvement of GJB2 noncoding regions in hearing loss (HL) has not been extensively investigated. However, three noncoding mutations, c.-259C>T, c.-23G>T, and c.-23+1G>A, were reported. Also, c.-684_-675del, of uncertain pathogenicity, was found upstream of the basal promoter. We performed a detailed analysis of GJB2 noncoding regions in Portuguese HL patients (previously screened for GJB2 codi...

PURPOSE The present study was initiated to establish the etiological causes of early onset hearing loss (HL) among Estonian children between 2000-2009. METHODS The study group consisted of 233 probands who were first tested with an arrayed primer extension assay, which covers 199 mutations in 7 genes (GJB2, GJB6, GJB3, SLC26A4, SLC26A5 genes, and two mitochondrial genes - 12S rRNA, tRNASer(UC...

Hearing loss due to mutations in the connexin gene family, which encodes gap junctional proteins, is a common form of hereditary deafness. In particular, connexin 26 (Cx26, GJB2) mutations are responsible for ~50% of non-syndromic hearing loss, which is the highest incidence of genetic disease. In the clinic, Cx26 mutations cause various auditory phenotypes ranging from profound congenital deaf...