Search for a genetic cause in children with unilateral isolated microtia and congenital aural atresia.

PURPOSE: Microtia describes a spectrum of auricular malformations ranging from mild dysplasia to anotia. A vast majority of microtia patients demonstrate congenital aural atresia (CAA). Isolated microtia has a right ear predominance (58-61%) and is more common in the male sex. Isolated microtia is a multifactorial condition involving genetic and environmental causes. The aim of this study is to describe the phenotype of children with unilateral isolated microtia and CAA, and to search for a common genetic cause trough DNA analysis. METHODS: Phenotyping included a complete clinical examination. Description on the degree of auricular malformation (Weerda classification-Weerda 1988), assessment for hemifacial microsomia and age-appropriate audiometric testing were documented. Computerized tomography of the temporal bone with 3-D rendering provided a histopathological classification (HEAR classification-Declau et al. 1999). Genetic testing was carried out by single nucleotide polymorphism (SNP) microarray. RESULTS: Complete data are available for 44 children (50% was younger than 33 days at presentation; 59.1% boys; 72.7% right ear). Type III microtia was present in 28 patients. Type 2b CAA existed in 32 patients. All patients had a normal hearing at the non-affected side. Genome wide deletion duplication analysis using microarray did not reveal any pathological copy number variant (CNV) that could explain the phenotype. CONCLUSIONS: Type III microtia (peanut-shell type) in combination with a type 2b CAA was the most common phenotype, present in 23 of 44 (52.3%) patients with isolated unilateral microtia. No abnormalities could be found by copy number variant (CNV) analysis. Whole exome sequencing in a larger sample with a similar phenotype may represent a future diagnostic approach.

Prekallikrein deficiency in a 15-year-old boy with Ménière's disease: a case report.

Congenital prekallikrein deficiency is a rare disorder in which there is an in vitro clotting defect despite absence of bleeding or thrombotic tendency. In this report, a 15-year-old boy with an unexpected markedly prolonged activated partial thrombin time, a normal prothrombin time, and without personal nor familial history of bleeding or thrombosis is presented. Laboratory investigation revealed a severe prekallikrein deficiency. This case highlights the importance of following a diagnostic algorithm to establish the correct diagnosis. Moreover, by selecting appropriate laboratory tests, unnecessary and repeatedly testing can be avoided.

Auditory neuropathy: a challenge for diagnosis and treatment.

In current terminology, auditory neuropathy spectrum disorder (ANSD) is a disease involving the disruption of the temporal coding of acoustic signals in auditory nerve fibres, resulting in the impairment of auditory perceptions that rely on temporal cues. There is debate about almost every aspect of the disorder, including aetiology, lesion sites, and the terminology used to describe it. ANSD is a heterogeneous disease despite similar audiological findings. The absence of an auditory brainstem response (ABR) and the presence of otoacoustic emissions (OAE) suggest an ANSD profile. However, to determine the exact anatomical site of the disorder, more in-depth audiological and electrophysiological tests must be combined with imaging, genetics and neurological examinations. Greater diagnostic specificity is therefore needed to provide these patients with more adequate treatment.

Case report: "auditory neuropathy" in a newborn caused by a cerebellopontine angle arachnoid cyst.

We present a 6-week-old girl, referred because of failed newborn hearing screening in the right ear. Click-evoked oto-acoustic emissions were present in both ears, auditory brainstem responses (ABR) were present in the left but totally absent in the right ear. A magnetic resonance imaging (MRI) study revealed a large arachnoid cyst in the right cerebellopontine angle (CPA) and a diagnosis of "auditory neuropathy/auditory dyssynchrony" was established. A microsurgical resection of the cyst wall and fenestration was performed by a retro sigmoid approach. This is the first case in the literature of auditory neuropathy (AN) in an infant caused by a cerebellopontine angle arachnoid cyst.

Prevalence of histologic otosclerosis: an unbiased temporal bone study in Caucasians.

BACKGROUND: 'Histologic otosclerosis' refers to a disease process without clinical symptoms or manifestations that can only be discovered by sectioning of the temporal bone at autopsy. 'Clinical otosclerosis' concerns the presence of otosclerosis at a site where it causes conductive hearing loss by interfering with the motion of the stapes or of the round window membrane. Various authors have studied the prevalence of histologic otosclerosis on laboratory collections of temporal bones. Some 12-15% of the temporal bones with histologic otosclerosis have demonstrated stapedial fixation. Using these figures for calculating the prevalence of clinical otosclerosis gives an extrapolated clinical prevalence of 0.99-1.2%. This does not correlate well with the clinical data on otosclerotic families from which a clinical prevalence of 0.3% has been estimated. OBJECTIVE: To study the prevalence of histologic otosclerosis in an unselected series of temporal bones. STUDY DESIGN: During a 1-year period, 118 consecutive pairs of temporal bones of deceased patients at a tertiary center were collected to determine the prevalence of otosclerosis. Although histology remains the gold standard for evaluation of otosclerosis, the gross observation of temporal bone slices combined with microradiography was used to screen for otosclerotic lesions more rapidly and with a lower cost-benefit ratio. The temporal bones with suspected otosclerosis shown with these techniques were further analyzed by conventional histology. RESULTS: 2.5% of the 236 temporal bones (or 3.4% of patients) studied demonstrated histologic otosclerosis. CONCLUSIONS: Although the prevalence of 2.5% is much lower than previously published figures on histologic otosclerosis, the extrapolated data (extrapolated clinical prevalence = 0.30-0.38%) correlate well with clinical studies of otosclerotic families. The previous studies based on laboratory collections were likely biased by the presence of hearing loss or other otological diseases.

Universal newborn hearing screening.

Hearing loss is one of the most common congenital anomalies, occurring in approximately 1-2 infants per 1000. Left undetected, hearing impairments in infants can negatively impact speech and language acquisition, academic achievement, social and emotional development. These negative impacts can be diminished and even eliminated through early intervention at or before 6 months of age. Reliable screening tests that minimize referral rates and maximize sensitivity and specificity are available. The goal of universal neonatal hearing screening is to maximize linguistic and communicative competence and literacy development for children who are hard of hearing or deaf. Audiologic and medical evaluations should be in progress before 3 months of age. Infants with confirmed hearing loss should receive intervention before 6 months of age from health care and education professionals with expertise in hearing loss and deafness in infants and young children.

The facio-audio-symphalangism syndrome in a four generation family with a nonsense mutation in the NOG-gene.

We report a four generation family with features of the facio-audio-symphalangism syndrome. This condition is characterized by proximal symphalangism, conductive hearing loss due to stapes fixation and a distinctive facies. A novel nonsense mutation in the NOG gene on chromosome 17q22 was identified in the patients. The variable expression and progressive nature of the syndrome is well illustrated by this family. The role of Noggin as the causative factor of symphalangism is discussed.

Otosclerosis: a genetically heterogeneous disease involving at least three different genes.

Otosclerosis is caused by abnormal bone homeostasis of the otic capsule, resulting in hearing impairment in 0.3%-0.4% of the white population. The etiology of the disease remains unclear and environmental as well as genetic factors have been implicated. We localized the first autosomal-dominant locus to chromosome 15 in 1998 (OTSC1) in an Indian family and, recently, we reported the localization of a second gene for otosclerosis to a 16 cM interval on chromosome 7q (OTSC2). In this study, we recruited and analyzed nine additional families (seven Belgian and two Dutch families with 53 affected and 20 unaffected subjects) to investigate the importance of these loci in autosomal-dominant otosclerosis. We completed linkage analysis with three microsatellite markers of chromosome 15 (D15S652, D15S1004, D15S657) and five microsatellite markers of chromosome 7 (D7S495, D7S2560, D7S684, D7S2513, D7S2426). In two families, results compatible with linkage to OTSC2 were found, but in the seven remaining families OTSC1 and OTSC2 were excluded. Heterogeneity testing provided significant evidence for genetic heterogeneity, with an estimated 25% of families linked to OTSC2. These results indicate that, besides OTSC1 and OTSC2, there must be at least one additional otosclerosis locus.

Hereditary otovestibular dysfunction and Ménière's disease in a large Belgian family is caused by a missense mutation in the COCH gene.

OBJECTIVE: To report the clinical, auditory, and vestibular characteristics of a nonsyndromic otovestibular dysfunction in a large Belgian family caused by a missense mutation of the DFNA9 gene: COCH. STUDY DESIGN: Retrospective study of the clinical, audiologic, and vestibular data of 60 genetically affected cases. SETTING: Tertiary referral center. PATIENTS: All members of a Belgian kindred who carry the genetic (P51S) defect linked to the inherited hearing and vestibular impairment. INTERVENTIONS: Diagnostic otologic, audiometric, and vestibular analysis and imaging. MAIN OUTCOME MEASURES: Pure tone audiometry, supraliminary audiometry. and vestibular investigation. RESULTS: The autosomal dominant inherited impairment was characterized by peripheral degeneration of the inner ear, leading to total deafness and bilateral vestibular areflexia. CONCLUSIONS: The genetically affected persons of a Belgian family shared a progressive sensorineural hearing loss starting between the third and sixth decade. Vestibular symptoms started at about the same age as the hearing loss. The vestibular symptoms consisted of instability in darkness, a tendency to fall sideways, light-headiness, a drunken feeling, and attacks of vertigo. Most of the patients reported tinnitus, and half of them reported pressure in the ears. Clinically, 9 of the 60 patients met the criteria for definite Ménière's disease, and another 13 and 17 patients met the criteria for probable or possible Ménière's disease, respectively. All 9 were older than the age of 35, but only 1 was older than 55 years, so more than 30% of the patients were between 35 and 55 years old. A specific pattern could be recognized in the evolution of the otovestibular impairment. Under the age of 35 years, almost all the affected family members had normal hearing, whereas above the age of 55 years, the hearing loss was at least moderate, and vestibular hypofunction occurred. In between, there was a transition period of two to three decades, when deterioration of the cochleovestibular function occurred, with a temporary audiometric and vestibular asymmetry.

Prevalence of otosclerosis in an unselected series of temporal bones.

BACKGROUND: Histologic otosclerosis is a disease process without clinical symptoms or manifestations that can be discovered only by sectioning of the temporal bone at autopsy. Clinical otosclerosis is otosclerosis at a site where it causes conductive hearing loss by interfering with the motion of the stapes or of the round window membrane. Various authors have studied the prevalence of histologic otosclerosis on laboratory collections of temporal bones. Some 12% to 15% of temporal bones with histologic otosclerosis have demonstrated stapedial fixation. Using these figures for calculating the prevalence of clinical otosclerosis gives an extrapolated clinical prevalence of 0.99% to 1.2%. This does not correlate well with the clinical data on otosclerotic families, from which a clinical prevalence of 0.3% has been estimated. OBJECTIVE: To study the prevalence of histologic otosclerosis in an unselected series of temporal bones. STUDY DESIGN: During a 1-year period, 118 consecutive pairs of temporal bones of deceased patients at a tertiary care center were collected to determine the prevalence of otosclerosis. Although histology remains the gold standard for evaluation of otosclerosis, the gross observation of temporal bone slices combined with microradiography was used to screen for otosclerotic lesions more rapidly and with a lower cost/benefit ratio. The temporal bones, which were suspected of having otosclerosis with these techniques, were further analyzed by conventional histology. RESULTS: 2.5% of the 236 temporal bones (or 3.4% of patients) studied demonstrated histologic otosclerosis. CONCLUSIONS: Although the prevalence of 2.5% is much lower than previously published figures on histologic otosclerosis, the extrapolated data (extrapolated clinical prevalence = 0.30% to 0.38%) correlate well with clinical studies of otosclerotic families. The previous studies based on laboratory collections were likely biased by hearing loss or other otologic diseases.

Mutations in the transcriptional activator EYA4 cause late-onset deafness at the DFNA10 locus.

We identified Eyes absent 4 (EYA4), a member of the vertebrate Eya family of transcriptional activators, as the causative gene of postlingual, progressive, autosomal dominant hearing loss at the DFNA10 locus. In two unrelated families from Belgium and the USA segregating for deafness at this locus, we found different mutations in EYA4, both of which create premature stop codons. Although EYA proteins interact with members of the SIX and DACH protein families in a conserved network that regulates early embryonic development, this finding shows that EYA4 is also important post-developmentally for continued function of the mature organ of Corti.

A second gene for otosclerosis, OTSC2, maps to chromosome 7q34-36.

Otosclerosis due to abnormal bone homeostasis of the otic capsule is a frequent cause of hearing loss in adults. Usually, the hearing loss is conductive, resulting from fixation of the stapedial footplate, which prevents normal ossicular vibration in response to sound. An additional type of sensorineural hearing loss may be caused by otosclerotic damage to the cochlea. The etiology of the disease is unknown, and both environmental and genetic factors have been implicated. Autosomal dominant inheritance with reduced penetrance has been proposed, but large families are extremely rare. To elucidate the pathogenesis of the disease, identification of the responsible genes is essential. In this study, we completed linkage analysis in a Belgian family in which otosclerosis segregates as an autosomal dominant disease. After excluding linkage to a known locus on chromosome 15 (OTSC1), we found linkage on chromosome 7q, with a multipoint LOD score of 3.54. Analysis of key recombinant individuals maps this otosclerosis locus (OTSC2) to a 16-cM interval on chromosome 7q34-36 between markers D7S495 and D7S2426.

Audiometric analysis of a Belgian family linked to the DFNA10 locus.

OBJECTIVE: To report the otologic and audiometric characteristics of a nonsyndromic postlingual sensorineural hearing impairment in a Belgian family linked to DFNA10. STUDY DESIGN: Retrospective study of the otologic and audiometric data of 17 genetically affected persons. SETTING: Tertiary referral center. PATIENTS: All members of a Belgian kindred who carried the haplotype linked to the inherited hearing impairment of DFNA10. INTERVENTIONS: Diagnostic otologic and audiometric analysis. MAIN OUTCOME MEASURES: Pure-tone audiometry. RESULTS: To find the frequencies that were most affected by the genetic defect, the excess hearing loss of the 17 patients was calculated per frequency in comparison with the respective p50 and p95 thresholds of the normal population. CONCLUSIONS: The genetically affected persons of a Belgian family shared a progressive symmetric sensorineural hearing loss that started in the first to fourth decade. Thirty-five percent of the affected family members had tinnitus, and only one patient had very mild vestibular complaints. At onset, hearing losses were mainly situated at the midfrequencies. With increasing age, all frequencies became affected. The hearing loss was initially mild, with a spontaneous evolution to a moderate or severe hearing impairment. The progression of the hearing loss for the pure-tone average (between 0.5 and 4 kHz) was 1.08 dB/year for this family, compared with 0.50 dB/year and 0.35 dB/year at the 95th and 50th percentiles of the normal population, respectively.

High prevalence of symptoms of Menière's disease in three families with a mutation in the COCH gene.

We report the genetic analysis of one large Belgian and two small Dutch families with autosomal dominant non-syndromic progressive sensorineural hearing loss associated with vestibular dysfunction. Linkage studies in the Belgian family mapped the disease to the DFNA9 locus on chromosome 14. Mutation analysis of the COCH gene, which is responsible for DFNA9, revealed a missense mutation changing a highly conserved residue. One of the patients, who had an earlier age of onset in comparison with most of the affected family members, was shown to be homozygous for the mutation. After the mutation was found in the Belgian family, we discovered that the same missense mutation was also present in two Dutch families with similar cochleo-vestibular symptoms. In all three families with hearing loss and imbalance problems, >25% of the patients showed additional symptoms, including episodes of vertigo, tinnitus, aural fullness and hearing loss. Clinically, these symptoms are consistent with the criteria for Menière's disease. The importance of genetic factors in Menière's disease has been suggested on many occasions, but this study is the first report of a mutation in a gene leading to the symptoms of Menière's disease in a significant portion of the carriers. The COCH gene may be one of the genetic factors contributing to Menière's disease and the possibility of a COCH mutation should be considered in patients with Menière's disease symptoms.

Mutations in the KCNQ4 gene are responsible for autosomal dominant deafness in four DFNA2 families.

We have previously found linkage to chromosome 1p34 in five large families with autosomal dominant non-syndromic hearing impairment (DFNA2). In all five families, the connexin31 gene ( GJB3 ), located at 1p34 and responsible for non-syndromic autosomal dominant hearing loss in two small Chinese families, has been excluded as the responsible gene. Recently, a fourth member of the KCNQ branch of the K+channel family, KCNQ4, has been cloned. KCNQ4 was mapped to chromosome 1p34 and a single mutation was found in three patients from a small French family with non-syndromic autosomal dominant hearing loss. In this study, we have analysed the KCNQ4 gene for mutations in our five DFNA2 families. Missense mutations altering conserved amino acids were found in three families and an inactivating deletion was present in a fourth family. No KCNQ4 mutation could be found in a single DFNA2 family of Indonesian origin. These results indicate that at least two and possibly three genes responsible for hearing impairment are located close together on chromosome 1p34 and suggest that KCNQ4 mutations may be a relatively frequent cause of autosomal dominant hearing loss.

Diagnosis and management strategies in congenital atresia of the external auditory canal. Study Group on Otological Malformations and Hearing Impairment.

This consensus report represents a distillation of current opinion regarding diagnosis and management of congenital aural atresia. It also takes into account the philosophical differences which exist in Europe. Congenital aural atresia requires prompt diagnosis, genetic counselling and an early assessment of hearing. In bilateral atresia, early amplification with a bone conduction hearing aid is essential for proper speech development. Further rehabilitation in bilateral cases is managed with surgical reconstruction in selected patients or by implantation of a bone-anchored hearing aid. Atresia repair surgery is worthwhile if proper patient selection is made by use of stringent audiological and radiological criteria and state of the art surgery is performed. The divergent views concerning indications, ideal age for surgery and surgical approach to achieve better hearing are discussed. Review of the literature demonstrated that even in the hands of the best surgeons a mean hearing gain of only 20-25 dB is achieved in atresia Type II, with 30-35 dB in Type I. Therefore, surgical reconstruction should only be done in the more favourable cases where post-operative hearing of <25-30 dB is attainable. Less favoured patients should be helped with bone-anchored hearing aids, as this type of surgery does not interfere with the future use of new techniques.

Linkage analysis of progressive hearing loss in five extended families maps the DFNA2 gene to a 1.25-Mb region on chromosome 1p.

Thus far, 13 genes for autosomal dominant hearing loss have been localized to specific chromosomal regions, but none of the genes has been cloned. Only a single family has been linked to each of these loci, with the exception of DFNA2. DFNA2 was originally mapped in two extended families originating from Indonesia and the United States. In this study we report linkage to DFNA2 in three additional large families with autosomal dominant hearing loss from Belgium and The Netherlands. These five DFNA2 families show a similar progressive sensorineural hearing loss, starting in the high frequencies and also affecting the middle and low frequencies later in life. Combining the information from all linked families, the candidate region that is most likely to contain the DFNA2 gene was reduced to a 1.25-Mb region between markers D1S432 and MYCL1. Different haplotypes segregating with the hearing loss were found in all five families, suggesting that different mutations are present in the same gene. These results indicate that DFNA2 is most likely an important gene for autosomal dominant hearing loss.

Subcutaneous diffuse neurofibroma of the neck: a case report.

A case of a rare and unusual variant of neurofibroma, diffuse neurofibroma (paraneurofibroma), in a young patient is presented. The clinical, radiological and histopathological features of this case are reported. The magnetic resonance imaging (MRI) features of the diffuse neurofibroma are comparable with those described in other neurofibromas.