Hearing impairment in MELAS: new prospective in clinical use of microRNA, a systematic review
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REVIEW
Open Access
Hearing impairment in MELAS: new prospective in clinical use of microRNA, a systematic review Arianna Di Stadio1* , Valentina Pegoraro1, Laura Giaretta1, Laura Dipietro2, Roberta Marozzo1 and Corrado Angelini1
Abstract Aim: To evaluate the feasibility of microRNAs (miR) in clinical use to fill in the gap of current methodology commonly used to test hearing impairment in MELAS patients. Material and method: A literature review was performed using the following keywords, i.e., MELAS, Hearing Loss, Hearing Impairment, Temporal Bone, Otoacustic Emission (OTOAE), Auditory Brain Response (ABR), and microRNA. We reviewed the literature and focused on the aspect of the temporal bone, the results of electrophysiological tests in human clinical studies, and the use of miR for detecting lesions in the cochlea in patients with MELAS. Results: In patients with MELAS, Spiral Ganglions (SG), stria vascularis (SV), and hair cells are damaged, and these damages affect in different ways various structures of the temporal bone. The function of these cells is typically investigated using OTOAE and ABR, but in patients with MELAS these tests provide inconsistent results, since OTOAE response is absent and ABR is normal. The normal ABR responses are unexpected given the SG loss in the temporal bone. Recent studies in humans and animals have shown that miRs, and in particular miRs 34a, 29b, 76, 96, and 431, can detect damage in the cells of the cochlea with high sensitivity. Studies that focus on the temporal bone aspects have reported that miRs increase is correlated with the death of specific cells of the inner ear. MiR − 9/9* was identified as a biomarker of human brain damage, miRs levels increase might be related to damage in the central auditory pathways and these increased levels could identify the damage with higher sensitivity and several months before than electrophysiological testing. Conclusion: We suggest that due to their accuracy and sensitivity, miRs might help monitor the progression of SNHL in patients with MELAS. Keywords: MELAS, Hearing loss, Hearing impairment, Otoacustic emission, Auditory brain response, microRNA, Diagnosis
Background MELAS, an acronym for myopathy, encephalopathy, lactic acidosis and stroke like episode syndrome [1], is a mitochondrial disease that can arise from 10 different mitochondrial DNA (mtDNA) mutations; in 80% of the cases it is caused by a 3243A > G point mutation in the leucine transfer RNA gene [1, 2]. The prevalence of the 3243A > G mutation in Caucasian population it has been * Correspondence: [email protected]; [email protected] 1 San Camillo Hospital IRCCS, Via Alberoni, 70 Venice, Italy Full list of author information is available at the end of the article
recently re-evaluated and authors identified a 0.24% of prevalence (236/ 1 00000) [3]. This mutation determines an alteration in the protein production by mRNA and change in complexes involved in the respiratory chain (I and IV) [1]. The alteration in metabolism deriving fr
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