Search Results (3)

Background/Objectives: Hearing loss is one of the most common sensorineural impairments, and approximately 60% of early-onset cases are due to genetic variations. The otogelin-like protein, encoded by the OTOGL gene, is a component of the acellular membranes of the inner ear, such as the tectorial membrane, and is thought to play an important role in cochlear amplification. OTOGL gene variants are a rare cause of hearing loss such as DFNB84B, a mild-to-moderate sensorineural hearing loss presenting in early childhood with autosomal recessive inheritance. In this study, we aim to enhance our comprehension of the phenotypes of hearing loss caused by OTOGL variants. Methods: A total of 7056 Japanese patients with hearing loss were recruited, and based on massively parallel DNA sequencing on 158 target genes, we selected patients with biallelic OTOGL variants. Results: Ten affected individuals with OTOGL gene variants were detected, the largest group of patients yet to be reported, and eight of the eleven variants were novel. Our results showed that variations in this gene led to mild-to-moderate non-progressive hearing loss, and the accompanying symptoms, mainly vestibular symptoms, were speculated to present in adulthood. Conclusions: Determination of the phenotypes of genes causative of hearing loss is expected to greatly benefit patients with hearing loss as it can assist in predicting outcomes and lead to appropriate intervention, which, in OTOGL-associated hearing loss cases, is based around the fact that the patients need not be concerned with deterioration in hearing, but require careful follow-up for vestibular symptoms. Full article

Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus. Full article

Musculocontractural Ehlers–Danlos syndrome (EDS) caused by pathogenic variants in CHST14 (mcEDS-CHST14) is a subtype of EDS characterized by multisystem malformations and progressive fragility-related manifestations. A recent international collaborative study showed that 55% of mcEDS-CHST14 patients had hearing loss (HL), more commonly of the high-frequency type. Here, we report the first systemic investigation of the otological features of patients with this disorder based on the world’s largest cohort at Shinshu University Hospital. Nine patients [18 ears; four male and five female patients; mean age, 18 years old (range, 10–28)] underwent comprehensive otological evaluation: audiogram, distortion product otoacoustic emission (DPOAE) test, and tympanometry. The audiogram, available in all 18 ears, showed HL in eight patients (8/9, 89%) and in 14 ears (14/18, 78%): bilateral in six patients (6/9, 67%) and unilateral in two (2/9, 22%); mild in eight ears (8/18, 44%) and moderate in six (6/18, 33%); and high-frequency HL in five (5/18, 28%) and low-frequency HL in five (5/18, 28%). An air-bone gap was detected in one ear (1/18, 6%). DPOAE was available in 13 ears, with the presence of a response in five (5/13, 38%) and the absence in eight (8/13, 62%), including in three ears of normal hearing. Tympanometry results were available in 12 ears: Ad type in nine (9/12, 75%) and As type in one (1/12, 8.3%). Patients with mcEDS-CHST14 had a high prevalence of HL, typically sensorineural and bilateral, with mild to moderate severity, of high-frequency or low-frequency type, and sometimes with no DPOAE response. The pathophysiology underlying HL might be complex, presumably related to alterations of the tectorial membrane and/or the basilar membrane of Corti associated with disorganized collagen fibril networks. Regular and careful check-ups of hearing using multiple modalities are recommended for mcEDS-CHST14 patients. Full article