Analysis Of Common Deafness Genes Mutations In Children With Profound Hearing Impairment And In Patients With Idiopathic Sudden Hearing Loss

Part IAnalysis of deafness gene chip testing Results in306children with profound hearing impairment in Hubei ProvinceObjective:Through detecting the common deafness gene mutations in306children with with profound sensorineural hearing loss in Hubei Province, we investigate the spectrum and incidence of the hot-spot deafness gene mutations in children, and in order to provide data reference for the implementation of screening of gene mutation and treatment of deafness in the region.Methods:Three hundred and six children with profound sensorineural hearing loss in Hubei Province were enrolled, including176male and130femal their genomic DNA were extracted from peripheral blood and a deafness gene test chip was used to screen nine hot spot mutation in the GJB2, GJB3, SLC26A4, and mitochondria12SrRNA gene. Other examination included deafness etiology questionnaires, clinical audiological examination, and physical examination. All patients with SLC26A4gene mutation were further given temporal bone CT scan.Results:1. Among306children,132(43.14%) were found out to be carries of at least one pathogenic gene mutation, with3showing double gene locus mutations. At the molecular level,26.80%(82/306) of the children can be diagnosed as hereditary deafness, and16.34%(50/306) of children were show the possibility of hereditary deafness.①GJB2gene mutation were seen in90(29.41%,90/306) cases. Among them,64(20.92%,64/306) cases were found homozygous or compound heterozygous mutation of GJB2gene. The rate of235delC mutation type was26.47%(81/306),35delG mutation type was not found;②SLC26A4gene mutation were seen in42(13.73%,42/306)ases. Among them,16(5.23%,16/306) cases showed homozygous or compound heterozygous mutation of SLC26A4gene. The rate of IVS7-2A>G mutation type was12.09%(37/306);③mitochondria DNA12SrRNAgene were seen2(0.65%,2/306) case, with one case showed compound1555A>G and2168A>G mutation.1494C＞T mutation type was not found.④The GJB3gene mutation was not found in children.2. Forty-two children carrying SLC26A4gene mutation were given temporal bone CT scan. Among them one case showed compound1555A>G and2168A>G mutation was exclude.16cases carrying homozygous or compound heterozygous mutation of SLC26A4gene were showed enlarged vestibular aqueduct,20cases carrying heterozygous mutation of SLC26A4gene were showed enlarged vestibular aqueduct. The concordance rate between genetic diagnosis and temporal bone CT was87.80%(36/41).Conclusions:1. Mutation of GJB2and SLC26A4gene are two major causes for genetic hearing loss pathogenic gene inpatients,235delC mutation is the main mutation type, followed by IVS7-2A>G mutation type.2. By analyzing the results of temporal bone CT in children carrying SLC26A4gene common mutations, it is showed that screening SLC26A4gene common mutations is useful in the diagnosis of enlarged vestibular aqueduct syndrome. Part IIThe study on235delC mutation of GJB2gene in patients with idiopathic sudden hearing lossObjective:To analyze the rate of235delC mutation in GJB2gene in patients with idiopathic sudden sensorineural hearing loss, and to explore its possible correlation with pathogenesis of idiopathic sudden hearing loss.Methods:From January2011to March2013, two hundred and thirty-four patients (male127cases, femal107cases) with diagnosis of idiopathic sudden hearing loss in otolaryngology department were recruited as experimental group. Eighty people (male46cases, femal34cases) with normal hearing level were enrolled as control group. Their peripheral blood samples were obtained and genomic DNA was extracted. Using polymerase chain reaction, the coding region of GJB2gene was amplified, and screened for235delC mutation in GJB2gene by restriction endonuclease. At same time the clinical data of234patients was collected to analyze.Results:In234cases of idiopathic sensorineural sudden hearing loss,5cases were found to have heterozygous235delC mutation, none of them harbored homozygous235delC mutation, the235delC mutation rate was2.1%(5/234). No235delC mutation was found in control group. The rate of235delC mutation in two group showed no statistically significant difference (P>0.05).Conclusions:This research shows that the rate of235delC mutation in GJB2is low in patients with idiopathic sudden hearing loss, and suggest that235delC mutation possible has no correlation with idiopathic sudden hearing loss.