Patrizia Trevisi

Occurrence of Del(GIB6-D13S1830) mutation in Italian non-syndromic hearing loss patients carrying a single GJB2 mutated allele

Molecular screening for GJB2 (connexin 26) mutations represents the standard diagnostic approach for the genotype definition of non-syndromic deafness. Nevertheless, a single GJB2 pathogenic mutation is detectable in a relevant number of cases, therefore failing to explain the phenotype. We aimed at assessing the occurrence of the recently described del(GIB6-D13S1830) mutation, occurring in the connexin 30 gene, in a group of Italian hearing-impaired patients carrying a single GJB2 mutated allele. A total of 59 non-syndromic hearing loss (NSHL) patients were screened for GJB2 mutations. Among these, nine NSHL patients were found to be heterozygous for a single GJB2 mutation. These patients, heterozygotes for different GJB2 mutated alleles (35delG, L90P, M34T, V153I), together with 11 additional 35delG/neg cases previously described, were studied for the presence of the del(GIB6-D13S1830) mutation. Two double heterozygotes del(GIB6-D13S1830)/35delG were identified. In both cases the degree of hearing loss was profound. Furthermore, GJB2 molecular screening led to the identification of a novel change (T55G) occurring in compound heterozygosity with the V37I mutation. In conclusion, our data suggest a significant frequency of del(GIB6-D13S1830) mutation in Italian hearing-impaired subjects (10% of unexplained GJB2 heterozygotes) similar to that reported in other European countries.

Evaluating benefits of cochlear implantation in deaf children with additional disabilities.

Objectives: Cochlear-implanted deaf children having additional disabilities may develop speech perception and language skills at a slower pace than their implanted peers without such disorders. Nevertheless, it has been shown that, even for these special cases, cochlear implantation (CI) provides benefits for a larger range of neuropsychological functions including social and relational skills. These benefits are frequently mentioned by parents, but rarely objectively measured by tests. This article presents a new evaluation tool aimed at assessing the global benefits offered by CI in these special cases. Design: The new tool has been designed as a closed-format questionnaire, divided into five areas. It is based on observing the frequency of preselected behaviors in daily activities, which imply specific social, neuropsychological, and perceptual skills. The questionnaire has been presented to the parents of 50 deaf children with additional disabilities, before and at least 6 months after CI. Results: The data show significant improvements in all investigated areas. However, not all skills improve in the same way, and only those skills related to language and communication correlate positively with time after implantation. The present article further discusses changes in skills for which parents have higher expectations, such as the preferred communication mode, speech intelligibility, and the ability to communicate on the telephone. Conclusions: The questionnaire has a simple-to-use format, and it has been proven to be sufficiently sensitive for the detection of changes in each examined area. Because the questionnaire is based on observed behaviors, it can be used even when other existing tests involve tasks that are too complex for these children.

Endocochlear inflammation in cochlear implant users: Case report and literature review

OBJECTIVES Cochlear implantation is a relatively safe procedure with a low complication rate. The overall rate of complications among cochlear implant patients ranges from 6% to 20%. Major complications are those that are life-threatening or require surgery, whereas minor complications are those that can be medically treated. Nonetheless, certain complications, even if highly rare, may require specific investigations and treatments. Among these rare complications are those with endocochlear involvement, such as cochleitis or labyrinthitis, with fibrosis or ossification that could lead to explantation. The aims of the present study were to report a particular case of post-operative cochleitis and to review the rate of complications after cochlear implantation, emphasising those conditions with proven endocochlear involvement. METHODS We refer to the case of an eight-year-old Italian boy affected by the sudden onset of headache, ipsilateral otalgia and facial paresis, who presented to our clinic for inexplicable worsening of the performance of his implant and his residual hearing, six years after surgery. A complete investigation including (clinical history, routine, autoimmune and serological blood tests, electrophysiological measurements from the cochlear implant and neuroimaging) was performed and is herein described. Additionally, a comprehensive review of the literature was conducted using internet search engines; 274 papers were selected, 88 of which were best suited to our purposes. RESULTS In our case, the progression of the symptoms and the performance decrement required explantation, followed by a complete recovery. Reviewing the literature revealed only three reports concerning cases of proven endocochlear phlogosis that required revision surgery. Wound swelling/infection and vertigo remain the two most common complications of cochlear implantation. Failure of the device is the third most frequent complication (10.06% of all complications and 1.53% of cochlear implantations). Other rare conditions (such as granulating labyrinthitis with cochlear fibrosis, ossification and erosion, silicone allergy and the formation of a biofilm around the internal device) are possible and unpredictable. Although rare (approximately 1%), such cases may require explantation. CONCLUSIONS Despite efforts by both surgeons and manufacturers, device-related and surgical complications still occur. These and other rare conditions demand specific management, and their frequency may be underestimated. Further studies are needed to assess more realistic rates of complications and devise more efficient strategies for early diagnosis and treatment.

Cochlear implant in Cogan syndrome.

Abstract Conclusions: Despite the need for special fitting strategies, improvements in speech discrimination tests support the use of cochlear implantation (CI) for patients with Cogan syndrome. Adequate preimplant counselling is mandatory, to prevent high expectations and to stress the necessity for bilateral implantation. Objective: In 60% of patients with Cogan syndrome, CI remains the only treatment option. Literature data agree that once the electrode array is properly inserted, functional outcomes are very good. Nevertheless, results may deteriorate due to progressive cochlear ossification. A few studies have documented the outcomes of CI in these patients, but none have reported the long-term results. Methods: This was a retrospective study describing the outcomes of 3 implanted patients with Cogan syndrome – among 300 adult patients who received a cochlear implant, 3 had become deaf due to Cogan syndrome. Results: In one patient the cochlear ossification advanced and the speech perception abilities worsened from the highest category to identification of words in closed set. The second patient complained of an abrupt reduction of loudness at 18 months post-implant, which required an increased electrical stimulation. The third patient reached the identification category probably due to auditory dyssynchrony, as an atypical consequence of the syndrome.

Five new OTOF gene mutations and auditory neuropathy

OBJECTIVE Purpose of this paper is to analyse OTOF gene in a series of subjects affected by auditory neuropathy. METHODS Four children showing mild to profound prelingual deafness, confirmed by the absence of a clear and detectable responses at auditory brainstem responses (ABR), associated with the presence of bilateral OAE, were enrolled in the study. RESULTS AND CONCLUSIONS Genetic analysis identified five new mutations (a nonsense, a small and a large deletion and two splicing site mutations), and one missense mutation (F1795C) previously described. These results further confirm the role of OTOF gene in auditory neuropathy. In the absence of a context of neurological syndrome, the combination of absent ABR and positive OAE responses should lead to an auditory neuropathy diagnosis and to a mutational screening in OTOF.

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.

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.

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.

Branchio-oto (BO) syndrome and oculoauriculo-vertebral phenotype: overlapping clinical findings in a child from a BO family

A three‐generation BO family is presented: the proband showed, in addition to branchio‐oto malformations, a severe condition with growth retardation, mandibular hypoplasia and vertebral anomalies resembling the oculo‐auriculo‐vertebral (OAV) phenotype. This family study supports the hypothesis of Rollnick and Kaye that the OAV spectrum may represent, in some cases, an extreme component of the BOR syndrome. The finding has relevant implications for genetic counselling regarding both conditions.

Audiological profiles and gjb2, gjb6 mutations: A retrospective study on genetic and clinical data from 2003 to 2008

In many world populations, mutations in the GJB2 gene (codifying for Connexin 26) are the most common causes of autosomal recessive non-syndromic hearing loss and account for approximately 50% of cases. To date, more than 100 (dominant or recessive) mutations have been identified (The Connexin Deafness Homepage, 2009) and differences in frequency and distribution across the world are significant. In European and American Caucasian populations, the 35delG is the most common mutation found to account for nearly 70% of the pathological alleles. Mutations in the GJB6 gene (codifying for Connexin 30) can co-occur in some cases (we refer to the 342-kb truncating deletion, named as GJB6-D13S1830). Thus, these mutations have been associated with autosomal recessive and non-syndromic hearing loss, mostly as biallelic/digenic inheritance of the Cx26 and/or Cx30. Our objective in this study was to describe audiological features and genotypes in patients with GJB2 and/or GJB6 mutations. We performed a retrospective study on a deaf cohort of 566 patients who underwent specific genetic tests for Connexin 26 and 30; the latter was investigated in 385 cases. GJB2 mutations were found in 162 patients and GJB6 mutations in five. The most common mutation of GJB2 was 35delG, a truncating (T) mutation, although we also found other types of truncating (nine genotypes) and non-truncating (NT) (11 genotypes) mutations, such as M34T, L90P, R184P, IVS1 + 1G→A, V37I, and E47X. Even if more than 70% of patients with biallelic/digenic mutations exhibit a severe/profound hearing impairment (even between the simple heterozygotes), mild/moderate deafness is also possible. Other interesting clinical data, such as atypical history or phenotype, were considered. In accordance with the literature, all categories of HL were found. The severe-profound HL was predominant especially in T/T, T/NT forms. The 35delG is the most common mutation that we found, especially in profound hearing impairment. Mild-moderate HL was identified overall among NT/NT forms. Our findings confirm the importance of newborn screening, and the evaluation of genetic mutations to define genotype/phenotype correlation and clinical or audiological features useful to early diagnosis and improvement of therapeutic protocols.