Novel Variant of FDXR as a Molecular Etiology of Postlingual Post-synaptic Auditory Neuropathy Spectrum Disorder via Mitochondrial Dysfunction: Reiteration of the Correlation between Genotype and Cochlear Implantation Outcomes.
Bong Jik Kim, Yujin Kim, Ju Ang Kim, Jin Hee Han, Min Young Kim, Hee Kyung Yang, Chae-Seo Rhee, Young Cheol Kang, Chun-Hyung Kim, Byung Yoon Choi
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引用次数: 0
Abstract
Objectives: FDXR encodes mitochondrial ferredoxin reductase, which is associated with auditory neuropathy spectrum disorder (ANSD) and optic atrophy. To date, only two studies have described FDXR-related hearing loss. The auditory rehabilitation outcomes of this disease entity have not been investigated, and the pathophysiological mechanisms remain incompletely understood. Here we report a hearing-impaired individual with co-segregation of the FDXR variant and post-synaptic type ANSD, who underwent cochlear implantation (CI) with favorable outcomes. We suggest a possible pathophysiological mechanism of adult-onset ANSD involving mitochondrial dysfunction.
Methods: A 35-year-old woman was ascertained to have ANSD. Exome sequencing identified the genetic cause of hearing loss, and a functional study measuring mitochondrial activity was performed to provide molecular evidence of pathophysiology. Expression of FDXR in the mouse cochlea was evaluated by immunohistochemistry. Intraoperatively, electrically evoked compound action potential (ECAP) responses were measured, and the mapping parameters were adjusted accordingly. Audiological outcomes were monitored for over 1 year.
Results: In lymphoblastoid cell lines (LCLs) carrying a novel FDXR variant, decreased ATP levels, reduced mitochondrial membrane potential, and increased reactive oxygen species levels were observed compared to control LCLs. These dysfunctions were restored by administering mitochondria isolated from umbilical cord mesenchymal stem cells, confirming the pathogenic potential of this variant via mitochondrial dysfunction. Partial ECAP responses during CI and FDXR expression in the mouse cochlea indicate that FDXR-related ANSD is post-synaptic. As a result of increasing the pulse width during mapping, the patient's CI outcomes showed significant improvement over 1-year post-CI.
Conclusion: A novel FDXR variant associated with mitochondrial dysfunction and post-synaptic ANSD was first identified in a Korean individual. Additionally, 1-year post-CI outcomes were reported for the first time in the literature. Excellent audiologic.
Results: were obtained, and our.
Results: reiterate the correlation between genotype and CI outcomes in ANSD.
期刊介绍:
Clinical and Experimental Otorhinolaryngology (Clin Exp Otorhinolaryngol, CEO) is an international peer-reviewed journal on recent developments in diagnosis and treatment of otorhinolaryngology-head and neck surgery and dedicated to the advancement of patient care in ear, nose, throat, head, and neck disorders. This journal publishes original articles relating to both clinical and basic researches, reviews, and clinical trials, encompassing the whole topics of otorhinolaryngology-head and neck surgery.
CEO was first issued in 2008 and this journal is published in English four times (the last day of February, May, August, and November) per year by the Korean Society of Otorhinolaryngology-Head and Neck Surgery. The Journal aims at publishing evidence-based, scientifically written articles from different disciplines of otorhinolaryngology field.
The readership contains clinical/basic research into current practice in otorhinolaryngology, audiology, speech pathology, head and neck oncology, plastic and reconstructive surgery. The readers are otolaryngologists, head and neck surgeons and oncologists, audiologists, and speech pathologists.