Molecular genetic analysis of mitochondrial DNA C1494T mutation in non-syndromic hearing loss of Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To conduct a molecular epidemiological survey on the mitochondrial DNA C1494T mutation in non-syndromic hearing loss patients in Chinese population.</p><p><b>METHODS</b>Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were used to screen the mitochondrial DNA 12S rRNA C1494T mutation in 20 patients with aminoglycoside antibiotic induced hearing loss, 136 sporadic non-syndromic hearing loss patients and 50 probands of pedigrees with non-syndromic hearing loss.</p><p><b>RESULTS</b>The C1494T mutation did not appear in all cases except for the positive control.</p><p><b>CONCLUSION</b>Incidence of mitochondrial DNA C1494T mutation is much lower than that of mitochondrial DNA A1555G mutation in non-syndromic hearing loss of Chinese population. Mitochondrial DNA C1494T mutation may be a rare variation in non-syndromic hearing loss and is not the main cause of aminoglycoside antibiotic induced-deafness.</p>

Adeno-associated virus-mediated Bcl-xL prevents aminoglycoside-induced hearing loss in mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Recent studies showed that aminoglycosides destroyed the cochlear cells and induced ototoxicity by producing reactive oxygen species, including free radicals in the mitochondria, damaging the membrane of mitochondria and resulting in apoptotic cell death. Bcl-x(L) is a well characterized anti-apoptotic member of the Bcl-2 family. The aim of this study was to determine the potential cochlear protective effect of Bcl-x(L) as a therapeutic agent in the murine model of aminoglycoside ototoxicity.</p><p><b>METHODS</b>Serotype 2 of adeno-associated virus (AAV2) as a vector encoding the mouse Bcl-x(L) gene was injected into mice cochleae prior to injection of kanamycin. Bcl-x(L) expression in vitro and in vivo was examined with Western blotting and immunohistochemistry separately. Cochlear dissection and auditory steady state responses were checked to evaluate the cochlear structure and function.</p><p><b>RESULTS</b>The animals in the AAV2-Bcl-x(L)/kanamycin group displayed better auditory steady state responses hearing thresholds and cochlear structure than those in the artificial perilymph/kanamycin or AAV2-enhanced humanized green fluorescent protein/kanamycin control group at all tested frequencies. The auditory steady state responses hearing thresholds and cochlear structure in the inoculated side were better than that in the contralateral side.</p><p><b>CONCLUSIONS</b>AAV2-Bcl-x(L) afforded significant preservation of the cochlear hair cells against ototoxic insults and protected the cochlear function. AAV2-mediated Bcl-x(L) might be an approach with respect to potential therapeutic application in the cochlear degeneration.</p>

Heterogeneous mutations of Wolfram syndrome I gene responsible for low frequency nonsyndromic hearing loss / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To explore the mutations of Wolfram syndrome I gene (WFS1) in families affected by non-syndromic low frequency sensorineural hearing loss (NS-LFSNHL).</p><p><b>METHODS</b>Twenty eight individuals from 6 pedigrees with hereditary non-syndromic low frequency sensorineural hearing loss as a dominant trait and cases of control were collected in the present study. The coding sequence of WFS1 gene was amplified by polymerase chain reaction (PCR), and direct DNA sequencing was performed to screen the entire coding region of the WFS1 gene for mutations in the WFS1.</p><p><b>RESULTS</b>Three heterozygous missense mutations (2016 G-->T, 2379 G-->4A, 2766 G-->A) in the WFS1 gene were found in two families. Mutations in WFS1 were identified in all patients tested of the two pedigrees. None of the mutations was found in at least 280 control chromosomes and normal individuals of the families. These missense mutations affecting conserved amino acids in two pedigrees.</p><p><b>CONCLUSIONS</b>Mutations in WFS1 are one of causes of non-syndromic low frequency sensorineural hearing loss, and the majority of mutations are missense mutations. Genetic counseling and genetic testing may be useful in the management of patients with this type of hearing loss.</p>