Causes of hearing impairment in the Norwegian paediatric cochlear implant program (original) (raw)
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Long-Term Cochlear Implant Outcomes in Children with GJB2 and SLC26A4 Mutations
PloS one, 2015
To investigate speech and language outcomes in children with cochlear implants (CIs) who had mutations in common deafness genes and to compare their performances with those without mutations. Prospective study. Patients who received CIs before 18 years of age and had used CIs for more than 3 years were enrolled in this study. All patients underwent mutation screening of three common deafness genes: GJB2, SLC26A4 and the mitochondrial 12S rRNA gene. The outcomes with CIs were assessed at post-implant years 3 and 5 using the Categories of Auditory Performance (CAP) scale, Speech Intelligibility Rating (SIR) scale, speech perception tests and language skill tests. Forty-eight patients were found to have confirmative mutations in GJB2 or SLC26A4, and 123 without detected mutations were ascertained for comparison. Among children who received CIs before 3.5 years of age, patients with GJB2 or SLC26A4 mutations showed significantly higher CAP/SIR scores than those without mutations at post...
Genetic evaluation of American minority pediatric cochlear implant recipients
International Journal of Pediatric Otorhinolaryngology, 2009
To review the results of genetic evaluation of American minority pediatric cochlear implant recipients over a 5-year period. Case series review of pediatric cochlear implant recipients of Caribbean Hispanic and African American admixture descent with severe to profound sensorineural hearing loss at a tertiary care children's hospital. Out of 28 patients receiving cochlear implants, 14 were of Caribbean Hispanic or African American admixture ancestry. Six (43%) had environmental risk factors for sensorineural hearing loss. Eight (57%) patients had presumed genetic sensorineural hearing loss; two of whom were syndromic and six non-syndromic. Patients with no clear etiology for hearing loss were tested for Gap Junction Beta 2 (GJB2) mutations. Within this admixture group, we found no biallelic mutations in GJB2, while two patients, both with environmental risk factors for sensorineural hearing loss, had monoallelic GJB2 variants. One patient of mixed ethnicity (Caribbean Hispanic, Turkish, Macedonian), not included as part of the 14, had the common Caucasian founder mutation, 35delG, along with a heterozygous polymorphism in the GJB2 gene. This extends previous data showing a paucity of GJB2 mutations in these admixture populations. We found no biallelic GJB2 mutations in our admixture cochlear implant population, and two sequence variants of the gene, only one of which was disease causing. This suggests that the incidence of GJB2 mutations in these admixture populations is low. Hence, there may be low cost-benefit of GJB2 mutation analysis in these admixture populations with severe to profound non-syndromic sensorineural hearing loss.
Balkan Journal of Medical Genetics, 2011
The 35delG mutation in the gap junction protein, b2, 26kDa (GJB2) gene is the most common mutation that has been found in children with non syndromic hearing loss. Testing for the GJB2 gene mutation is simple and can directly answer the concerns of the parents about cause of the disorder and prognosis for their children. Cochlear implantation (CI) is one of the methods of hearing rehabilitation in patients with complete hearing loss. The present study was designed for genetic assessment of children who were referred for CI.
GJB2 mutations and additional disabilities in a pediatric cochlear implant population
International journal of pediatric otorhinolaryngology, 2006
Children with severe to profound sensorineural hearing loss due to GJB2 mutations have often been deemed good cochlear implant candidates. Studies on children with GJB2 mutations and cochlear implants have typically excluded children with additional disabilities. To investigate the presence of additional disabilities among children with and without GJB2 mutations in a cochlear implant population. A retrospective chart review was performed of children with non-syndromic sensorineural hearing loss (SNHL) who received a cochlear implant between 1993 and 2004. Among 108 children within the cochlear implant database; 46 patients met the inclusion criteria of idiopathic non-syndromic hearing loss. Sixteen children had GJB2 mutations, 12 were GJB2 negative, and 17 did not receive GJB2 testing but had no other identifiable etiology or risk factor contributing to hearing loss. The proportion of children with additional disabilities that would affect either pre-operative assessments or post-o...
Molecular study in Brazilian cochlear implant recipients
American Journal of Medical Genetics Part A, 2007
The most common form of non-syndromic autosomal recessive deafness (NSRD) is caused by mutations in the GJB2 gene. Recently, a deletion truncating the GJB6 gene, called del(GJB6-D13S1830) has also been described normally accompanying mutations in another allele of the GJB2 gene. Among all the mutations described to date, 35delG in the GJB2 gene is the most common. Preliminary data suggest that pathologic changes due to GJB2 mutations do not affect the spiral ganglion cells, which are the site of stimulation of the cochlear implant. Besides, the survival of the spiral ganglion cells is believed to be an important determinant of the outcome after surgery. Therefore, we have studied 49 non-syndromic deaf patients with unknown etiologies in order to determine the prevalence of GJB2 and GJB6 gene mutations in patients undergoing cochlear implantation surgery. Also, the molecular studies were performed using polymerase chain reaction amplification and direct sequencing. As a result, we found 19 individuals with GJB2 mutation including one new mutation (K168R), one patient homozygous for the del(GJB6-D13S1830). These results establish that genetic screening can provide an etiologic diagnosis, and may help with prognosis after cochlear implantation, as has been hypothesized in previous studies. ß 2007 Wiley-Liss, Inc.
Prevalence of DFNB1 mutations among cochlear implant users in Slovakia and its clinical implications
European Archives of Oto-Rhino-Laryngology, 2013
Hereditary etiology plays an important role in bilateral profound deafness as a main indication for cochlear implantation. Mutations in DFNB1 locus account for most of the inherited deafness cases in Caucasians. To provide actual data on mutation prevalence among implanted deaf subpopulation, we performed DNA analysis of GJB2 and GJB6 genes in 131 unrelated Slovak cochlear implant users. Eight previously described causal mutations and one probably pathogenic missense variant (c.127G[A) were detected in the GJB2 gene in 58 (44.28 %) subjects. The most common mutation found was c.35delG with frequency 83.02 % of all disease alleles, followed by c.71G[A, c.1-3201G[A, c.313_326del14, c.109G[A, 167delT, c.269T[C, and c.333_334delAA. GJB6 deletion delD13S1830 was identified in only one subject, in double heterozygosity with a GJB6 mutation. Thus, the deafness cause could be clearly attributable to DFNB1 mutations in 36.64 % of the patients examined. In summary, the mutation profile found in our cohort was similar to the mutation spectrum reported for Central European deaf populations. The mutation prevalence in cochlear implant users was, however, almost by 25 % higher than previously established for non-implanted hearing-impaired population in Slovakia. Finally, we also demonstrate a certain variability in deafness onset in patients with causal genotype and coincidence with other risk factors for deafness. Our results underline the importance of genetic tests in all cochlear implant candidates. Keywords Connexin Á Deafness Á Cochlear implantation Á DNA analysis Á Etiology L. Varga and I. Mašindová have contributed equally to this work.
2011
Clinical application of mutation screening and its effect on the outcome of cochlear implantation is widely debated. We investigated the effect of mutations in GJB2 gene on the outcome of cochlear implantation in a population with a high rate of consanguineous marriage and autosomal recessive nonsyndromic hearing loss. Two hundred and one children with profound prelingual sensorineural hearing loss were included. Forty-six patients had 35delG in GJB2. Speech awareness thresholds (SATs) and speech recognition thresholds (SRTs) improved following implantation, but there was no difference in performance between patients with GJB2-related deafness versus control (all P > 0.10). Both groups had produced their first comprehensible words within the same period of time following implantation (2.27 months in GJB2-related deaf versus 2.62 months in controls, P = 0.22). Although our findings demonstrate the need to uncover unidentified genetic causes of hereditary deafness, they do not support the current policy for genetic screening before cochlear implantation, nor prove a prognostic value.
Cochlear Implant Outcomes and Genetic Mutations in Children with Ear and Brain Anomalies
BioMed Research International, 2015
Background. Specific clinical conditions could compromise cochlear implantation outcomes and drastically reduce the chance of an acceptable development of perceptual and linguistic capabilities. These conditions should certainly include the presence of inner ear malformations or brain abnormalities. The aims of this work were to study the diagnostic value of high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in children with sensorineural hearing loss who were candidates for cochlear implants and to analyse the anatomic abnormalities of the ear and brain in patients who underwent cochlear implantation. We also analysed the effects of ear malformations and brain anomalies on the CI outcomes, speculating on their potential role in the management of language developmental disorders. Methods. The present study is a retrospective observational review of cochlear implant outcomes among hearing-impaired children who presented ear and/or brain anomalies at neuroimaging investigations with MRI and HRCT. Furthermore, genetic results from molecular genetic investigations (GJB2/GJB6 and, additionally, in selected cases, SLC26A4 or mitochondrial-DNA mutations) on this study group were herein described. Longitudinal and cross-sectional analysis was conducted using statistical tests. Results. Between January 1, 1996 and April 1, 2012, at the ENT-Audiology Department of the University Hospital of Ferrara, 620 cochlear implantations were performed. There were 426 implanted children at the time of the present study (who were <18 years). Among these, 143 patients (64 females and 79 males) presented ear and/or brain anomalies/lesions/malformations at neuroimaging investigations with MRI and HRCT. The age of the main study group (143 implanted children) ranged from 9 months and 16 years (average = 4.4; median = 3.0). Conclusions. Good outcomes with cochlear implants are possible in patients who present with inner ear or brain abnormalities, even if central nervous system anomalies represent a negative prognostic factor that is made worse by the concomitant presence of cochlear malformations. Common cavity and stenosis of the internal auditory canal (less than 2 mm) are negative prognostic factors even if brain lesions are absent.
Frontiers in Genetics, 2020
The use and utility of cochlear implantation has rapidly increased in recent years as technological advances in the field have expanded both the efficacy and eligible patient population for implantation. This review aims to serve as a general overview of the most common hearing disorders that have favorable auditory outcomes with cochlear implants (CI). Hearing loss in children caused by congenital cytomegalovirus infection, syndromic conditions including Pendred Syndrome, and non-syndromic genetic conditions such as hearing impairment associated with GJB2 mutations have shown to be successfully managed by CI. Furthermore, cochlear implantation provides the auditory rehabilitation for the most common etiology of hearing loss in adults and age-related hearing loss (ARHL) or presbycusis. However, in some cases, cochlear implantation have been associated with some challenges. Regarding implantation in children, studies have shown that sometimes parents seem to have unrealistic expectations regarding the ability of CI to provide auditory rehabilitation and speech improvement. Given the evidence revealing the beneficial effects of early intervention via CI in individuals with hearing disorders especially hearing loss due to genetic etiology, early auditory and genetic screening efforts may yield better clinical outcomes. There is a need to better understand genotype-phenotype correlations and CI outcome, so that effective genetic counseling and successful treatment strategies can be developed at the appropriate time for hearing impaired individuals.
Cochlear implantation in common forms of genetic deafness
International Journal of Pediatric Otorhinolaryngology, 2010
Genetic factors are among the main etiologies of severe to profound hearing loss and may play an important role in cochlear implantation (CI) outcomes. While genes for common forms of deafness have been cloned, efforts to correlate the functional outcome of CIs with a genetic form of deafness carried by the patient have been largely anecdotal to date. It has been suggested that the differences in auditory performance may be explained by differences in the number of surviving spiral ganglion cells, etiology of hearing loss, and other factors. Knowledge of the specific loci and mutations involved in patients who receive cochlear implants may elucidate other factors related to CI performance. In this review article, current knowledge of cochlear implants for hereditary hearing loss will be discussed with an emphasis on relevant clinical genotype-phenotype correlations.