Neo-oval window technique and myringo-chorda-vestibulopexy in the BOR syndrome

A Novel EYA1 Mutation Causing Alternative RNA Splicing in a Chinese Family With Branchio-Oto Syndrome: Implications for Molecular Diagnosis and Clinical Application

OBJECTIVES

Branchio-oto syndrome (BOS) primarily manifests as hearing loss, preauricular pits, and branchial defects. EYA1 is the most common pathogenic gene, and splicing mutations account for a substantial proportion of cases. However, few studies have addressed the structural changes in the protein caused by splicing mutations and potential pathogenic factors, and several studies have shown that middle-ear surgery has limited effectiveness in improving hearing in these patients. BOS has also been relatively infrequently reported in the Chinese population. This study explored the genetic etiology in the family of a proband with BOS and provided clinical treatment to improve the patient's hearing.

METHODS

We collected detailed clinical features and peripheral blood samples from the patients and unaffected individuals within the family. Pathogenic mutations were identified by whole-exome sequencing and cosegregation analysis and classified according to the American College of Medical Genetics and Genomics guidelines. Alternative splicing was verified through a minigene assay. The predicted three-dimensional protein structure and biochemical experiments were used to investigate the pathogenicity of the mutation. The proband underwent middle-ear surgery and was followed up at 1 month and 6 months postoperatively to monitor auditory improvement.

RESULTS

A novel heterozygous EYA1 splicing variant (c.1050+4 A>C) was identified and classified as pathogenic (PVS1(RNA), PM2, PP1). Skipping of exon 11 of the EYA1 pre-mRNA was confirmed using a minigene assay. This mutation may impair EYA1-SIX1 interactions, as shown by an immunoprecipitation assay. The EYA1-Mut protein exhibited cellular mislocalization and decreased protein expression in cytological experiments. Middle-ear surgery significantly improved hearing loss caused by bone-conduction abnormalities in the proband.

CONCLUSION

We reported a novel splicing variant of EYA1 in a Chinese family with BOS and revealed the potential molecular pathogenic mechanism. The significant hearing improvement observed in the proband after middle-ear surgery provides a reference for auditory rehabilitation in similar patients.

Anatomical and audiological considerations in branchiootorenal syndrome: A systematic review

Objective

Establish anatomical considerations, audiological outcomes, and optimal management in patients with branchiootic/branchiootorenal syndrome (BO/BOR).

Methods

Databases reviewed: Medline, Pubmed, Embase, Web of Science, Cochrane Collection, and ClinicalTrials.gov. Clinical or radiological studies of patients with BOR syndrome describing either the audiological profile or anatomical changes were included. Articles in which BOR syndrome was associated with other syndromes, and those that were focused only on general and genetic aspects of BOR syndrome were excluded. Articles were assessed using Oxford Centre for Evidence‐Based Medicine (OCEBM) grading system and the Brazzelli risk of bias tool for nonrandomized studies.

Results

Searches identified 379 articles. Of these, 64 studies met the inclusion criteria, reporting outcomes in 482 patients from at least 95 families. In 308 patients, hearing loss was categorized as sensorineural (29%), conductive (20%), and mixed (51%). Hearing outcomes were variable in terms of onset, pattern, and severity; ranging from mild to profound deafness. One hundred sixty‐nine patients presented with inner ear anomalies, 145 had middle, and 151 had external ear abnormalities. In 44 studies, 58 ear operations were described. Mixed outcomes were reported in patients managed with hearing aids or middle ear surgery; however, successful cochlear implantation was described in all five cases.

Conclusion

The anatomical and audiological profiles of patients with BO/BOR are variable. A range of surgical procedures were described, however lacked objective outcome measures. Given the range of anatomical variants, management decisions should be made on an individual basis including full audiological and radiological assessment.

Level of evidence

NA.

Phenotypic consequences in a Japanese family having branchio-oto-renal syndrome with a novel frameshift mutation in the gene EYA1

Branchio-oto-renal (BOR) syndrome is an autosomal dominant inherited disorder characterized by malformations of the ear associated with hearing impairment, branchial fistulae or cysts, and renal malformations. Mutations in the gene EYA1 have been found to be responsible for BOR syndrome in approximately 40% of the subjects. Here we report a Japanese family with BOR syndrome associated with a frameshift mutation in EYA1. This mutation, 1667-1668insT, has not been previously reported and is also the first frameshift mutation in exon 16 of this gene. We describe the detailed clinical features and medical highlights of the family members, and based on their clinical histories we propose that genetic testing for EYA1 mutations would contribute to the diagnosis of BOR syndrome, facilitate genetic counseling for recurrence, give precautions regarding possible renal disorders later in life, and impact the consideration of surgical intervention for middle ear anomalies.

Surgical management of conductive hearing loss in children

Patients with congenital conductive hearing loss present a surgical challenge. Surgeons must be aware of the potential altered anatomy, in particular the potential risks to the facial nerve and inner ear structures; however, meticulous attention to detail in the preoperative evaluation and in the operating room can minimize these risks. If surgery poses too high a risk to these structures, the chances of success are low, or there is a contraindication to surgery, traditional air-conduction hearing aids or bone-anchored hearing aids should be considered.

Temporal bone anomalies in the branchio-oto-renal syndrome: detailed computed tomographic and magnetic resonance imaging findings

OBJECTIVE

To inventory computed tomographic and magnetic resonance imaging findings in the branchio-oto-renal (BOR) syndrome.

STUDY DESIGN

A prospective computed tomographic and magnetic resonance imaging study on a family with the BOR syndrome.

SETTING

Department of medical imaging and magnetic resonance imaging at St. Jan Brugge, Brugge, Belgium.

PATIENTS

Eight affected members of a Belgian family. Younger affected family members were excluded because of their age.

RESULTS

Computed tomography showed inner ear malformations in all eight affected patients. Magnetic resonance imaging was performed on five patients and showed inner ear malformations. To define hypoplasia or congenital enlargement of the inner ear structures, measurements obtained from a control group of normal subjects were used for comparison. Almost symmetrical cochlear abnormalities were observed on the three-dimensional Fourier transformation-constructive interference in steady state images of the five patients who underwent magnetic resonance imaging; four had dysplasia of the cochlea, and one had hypoplasia. The vestibule was slightly enlarged in one patient; computed tomography and magnetic resonance imaging showed semicircular canal malformations. Magnetic resonance imaging clearly showed bilateral enlarged endolymphatic sacs and ducts, whereas computed tomography showed only unilateral widening of the vestibular aqueduct and borderline widening of the vestibular aqueduct. Magnetic resonance imaging showed bilateral hypoplasia of the cochlear branch of the eighth nerve in one patient.

CONCLUSION

Hypoplasia and dysplasia of the cochlea were consistent findings, and only magnetic resonance imaging was able to evaluate the intracochlear changes in detail and corrected computed tomography in most patients. Moreover, magnetic resonance imaging also detected bilateral hypoplasia of the cochlear branch of the eighth nerve in one patient. A widened vestibular aqueduct and a widened vestibular sac were frequent but not obligatory features of the BOR syndrome. Other malformations of the middle ear included a reduced middle ear cavity and malformations of the ossicular chain.

The presence of a widened vestibular aqueduct and progressive sensorineural hearing loss in the branchio-oto-renal syndrome. A family study

OBJECTIVE

A new large family with the BOR syndrome is reported with special reference to the presence of a widened vestibular aqueduct and a progressive sensorineural component in the mixed hearing loss. A review of the BOR literature of 184 patients is given.

SETTING

University Hospitals.

RESULTS

A BOR family with 17 affected members was studied. Fourteen of those 17 were still alive and 12 of those cooperated in this clinical study. Detailed radiological studies showed in three out of 12 affected family members a widened vestibular aqueduct and progressive sensorineural hearing loss. This raises the question whether there is a true correlation or whether those are coincidental.

CONCLUSION

In our family with the Branchio-Oto-Renal syndrome, a widened vestibular aqueduct and progressive hearing loss is found in a few affected family members. Imaging of the temporal bones and long-term audiometric follow-up could help to reveal whether the widened vestibular aqueduct is the cause for the progressive hearing loss.

Branchio-oto-renal syndrome: identification of novel mutations, molecular characterization, mutation distribution, and prospects for genetic testing

The branchio-oto-renal syndrome (BOR) is an autosomal dominant disorder characterized by branchial clefts, preauricular sinuses, hearing loss, and renal anomalies. The BOR gene, EYA1, on chromosome 8q13 has recently been cloned and mutations have been identified. In this study, we have analyzed the sites of mutations in the EYA1 gene in BOR patients to determine the spectrum of mutations. We have identified two missense mutations and have compared all the mutations reported to date in the EYA1 gene. In total, 20 mutations have been described, the majority of which are clustered in the carboxy-terminal region of the gene. The clinical features of the BOR individuals have also been compared to determine if the nature of the mutation correlates with the type and severity of the clinical symptoms. Most of the mutations arose de novo and, other than the clustering in carboxy-terminal exons 9-16, no mutation hot spots have been identified. These results provide the basis for molecular genetic testing that will help in the clinical evaluation and genetic counseling of members of BOR families.

Branchio-oto-renal syndrome

Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder with branchial, otologic, and renal manifestations. The branchial manifestations usually are inconsequential, however the hearing impairment and renal malformations can be significant. The disease is caused by mutations in the EYA1 gene.

Phenotypic manifestations of branchio-oto-renal syndrome

Branchiootorenal (BOR) syndrome is a variable, autosomal-dominant disorder of the first and second embryonic branchial arches, kidneys, and urinary tract. We describe the phenotype in 45 individuals, highlighting differences and similarities reported in other studies. Characteristic temporal bone findings include cochlear hypoplasia (4/5 of normal size with only 2 turns), dilation of the vestibular aqueduct, bulbous internal auditory canals, deep posterior fossae, and acutely-angled promontories.

Ear surgery in Treacher Collins syndrome

The autosomal dominant hereditary Treacher Collins syndrome manifests itself phenotypically in dysmorphogenesis of particularly the first, but also the second branchial arch system. Consequently, 50% of patients with Treacher Collins syndrome have a congenital, generally pure conductive hearing loss resulting from a major or minor ear anomaly. The outcome of surgery to improve patients' hearing varies and is sometimes even disappointing. Thorough analysis of 33 cases (39 operated ears) and the strict application of a classification for the anomaly to each ear enabled us to gain insight into the most suitable surgical policy and to form a prognosis for reconstructive ear surgery.

The deafness, pre-auricular sinus, external ear anomaly and commissural lip pits syndrome--otological, vestibular and radiological findings

Commissural lip pits, pinna dysplasia, pre-auricular sinus and hearing loss constitute a recently described autosomal dominant branchial arch syndrome. In a large family, eight out of the 74 members were also affected by conductive hearing loss. No inner ear abnormalities could be demonstrated on the CT scans. In three patients (four ears) out of four patients (six ears), exploratory tympanotomy revealed serious ossicular chain anomalies. In one ear, round window aplasia was also present. Long-term hearing improvement could only be achieved in one ear.