Navigating the Usher Syndrome Genetic Landscape: An Evaluation of the Associations between Specific Genes and Quality Categories of Cochlear Implant Outcomes.

Usher syndrome (US) is a clinically and genetically heterogeneous disorder that involves three main features: sensorineural hearing loss, retinitis pigmentosa (RP), and vestibular impairment. With a prevalence of 4-17/100,000, it is the most common cause of deaf-blindness worldwide. Genetic research has provided crucial insights into the complexity of US. Among nine confirmed causative genes, MYO7A and USH2A are major players in US types 1 and 2, respectively, whereas CRLN1 is the sole confirmed gene associated with type 3. Variants in these genes also contribute to isolated forms of hearing loss and RP, indicating intersecting molecular pathways. While hearing loss can be adequately managed with hearing aids or cochlear implants (CIs), approved RP treatment modalities are lacking. Gene replacement and editing, antisense oligonucleotides, and small-molecule drugs hold promise for halting RP progression and restoring vision, enhancing patients' quality of life. Massively parallel sequencing has identified gene variants (e.g., in PCDH15) that influence CI results. Accordingly, preoperative genetic examination appears valuable for predicting CI success. To explore genetic mutations in CI recipients and establish correlations between implant outcomes and involved genes, we comprehensively reviewed the literature to gather data covering a broad spectrum of CI outcomes across all known US-causative genes. Implant outcomes were categorized as excellent or very good, good, poor or fair, and very poor. Our review of 95 cochlear-implant patients with US, along with their CI outcomes, revealed the importance of presurgical genetic testing to elucidate potential challenges and provide tailored counseling to improve auditory outcomes. The multifaceted nature of US demands a comprehensive understanding and innovative interventions. Genetic insights drive therapeutic advancements, offering potential remedies for the retinal component of US. The synergy between genetics and therapeutics holds promise for individuals with US and may enhance their sensory experiences through customized interventions.

Cochlear Implant Outcomes and Genetic Mutations in Children with Ear and Brain Anomalies.

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.

Association between idiopathic hearing loss and mitochondrial DNA mutations: a study on 169 hearing-impaired subjects.

Mutations in mitochondrial DNA (mtDNA) have been shown to be an important cause of sensorineural hearing loss (SNHL). In this study, we performed a clinical and genetic analysis of 169 hearing-impaired patients and some of their relatives suffering from idiopathic SNHL, both familial and sporadic. The analysis of four fragments of their mtDNA identified several polymorphisms, the well known pathogenic mutation, A1555G, and some novel mutations in different genes, implying changes in the aminoacidic sequence. A novel sporadic mutation in 12S rRNA (MT-RNR1), not previously reported in the literature, was found in a case of possible aminoglycoside-induced progressive deafness.

Association of the 4 g/5 g polymorphism of plasminogen activator inhibitor-1 gene with sudden sensorineural hearing loss. A case control study.

BACKGROUND: The 5 G/5 G genotype of PAI-1 polymorphism is linked to decreased plasminogen activator inhibitor-1 (PAI-1) levels and it has been suggested that lower PAI-1 levels may provide protective effects on inflammation, local microcirculatory disturbance, and fibrotic changes, which are likely associated with development of sudden sensorineural hearing loss (SSNHL). METHODS: The association of the 4 G/5 G PAI-1 polymorphism with the development and clinical outcome of SSNHL is evaluated via a case control study. 103 patients with SSNHL and 113 age and sex-matched controls were enrolled at University of Ferrara, Italy and hearing loss outcome was measured at least 3 months after the onset of hearing loss. DNA was isolated from peripheral blood using the QIAamp kit and the 4 G/5 G polymorphism in the -675 promoter region was genotyped with an allele-specific PCR. Genotype distribution was tested in patients and compared to controls by chi-square and odd-ratio analysis. The codominant and recessive models were used for the multiple logistic regression analyses of the PAI-1 gene allele. RESULTS: In this population, 5 G/5 G genotype had a two-time lower frequency in SSNHL patients compared to healthy controls (15.5% vs 30.1%) and was associated with decreased odds compared to 4 G/5 G genotype (OR 0.37, 95% CI 0.19-0.75, p = 0.005). In addition, the patients with 5 G/5 G genotype showed a trend of more than 2 times higher ratio of hearing recovery (> 20 dB) after systemic corticosteroid treatment compared to 4 G/5 G genotype (OR 2.3, 95% CI 0.32 - 16.83, p = 0.39), suggesting a better clinical outcome. CONCLUSIONS: The 5 G/5 G genotype of PAI-1 may be associated with a reduced risk of SSNHL in the Italian population.

Novel mutations in the SLC26A4 gene.

OBJECTIVES: Mutations in the SLC26A4 gene (7q22.3-7q31.1) are considered one of the most common causes of genetic hearing loss. There are two clinical forms related to these mutations: syndromic and non-syndromic deafness. The first one is named Pendred Syndrome (PS) when deafness is associated with thyroid goiter; the second is called DFNB4, when no other symptoms are present. Both are transmitted as an autosomal recessive trait, but simple heterozygotes can develop both forms of deafness. Actually it is thought that Pendred Syndrome occurs when both alleles of SLC26A4 gene are mutated; DFNB4 seems due to monoallelic mutations. PS and DFNB4 can be associated with inner ear malformations. In most of the cases (around 80%), these consist in Enlarged Vestibular Aqueduct (EVA). EVA can also be present without SLC26A4 mutations. Understanding the role of new SLC26A4 variants should facilitate clinical assessment, as well as diagnostic and therapeutic approaches. This investigation aims to detect and report genetic causes of two unrelated Italian boys with hearing loss. METHODS: Patients and family members underwent clinical, audiological and genetic evaluations. To identify genetic mutations, DNA sequencing of SLC26A4 gene (including all 21 exons, exon-intron boundaries and promoter region) was carried out. RESULTS: Both probands were affected by congenital, progressive and fluctuating mixed hearing loss. Temporal bone imaging revealed a bilateral EVA with no other abnormalities in both cases. Probands were heterozygotes for previously undescribed mutations in the SLC26A4 gene: R409H/IVS2+1delG (proband 1) and L236P/K590X (proband 2). No other mutations were detected in GJB2, GJB6 genes or mitochondrial DNA (mit-DNA). CONCLUSIONS: The IVS2+1delG and K590X mutations have not yet been described in literature but there is some evidence to suggest that they have a pathological role. The results underlined the importance of considering the complete DNA sequencing of the SLC26A4 gene for differential molecular diagnosis of deafness, especially in those patients affected by congenital, progressive and fluctuating mixed hearing loss with bilateral EVA.

LAMM syndrome with middle ear dysplasia associated with compound heterozygosity for FGF3 mutations.

We report on the first cases of FGF3 compound heterozygotes in two European families from non-consanguineous marriages, affected with labyrinthine aplasia, microtia, and microdontia (LAMM) Syndrome. Three not previously described mutations (p.W153VfsX51, p.Y106C, and p.Y49C) and a recurrent one (p.R104X) were found. Analysis of 50 unrelated control subjects (100 chromosomes) of the same European background did not show any of the two newly reported missense variations. We confirm the absence of otodental syndrome in heterozygous carriers, but report unilateral microtia in one of them. We also report on the involvement of the middle ear structures in LAMM Syndrome.

The universal newborn hearing screening program at the University Hospital of Ferrara: focus on costs and software solutions.

In the present paper, the authors report the results of the Universal Newborn Hearing Screening (UNHS) project at the University Hospital of Ferrara. A total of 6,759 full-term newborns and a total of 1,016 NICU babies were tested at the University Hospital of Ferrara, from January 2000 to December 2006. The paper presents information from clinically acceptable screening procedures developed and tested during the 6 years of the program and addresses two questions pertinent to hearing screening: (i) the cost-estimate of a UNHS program based on European economical and administration premises and (ii) the development of a database-structure for the evaluation of the UNHS/NHS performance and the individual patient tracking.