title: Genetic mutations in nonsyndromic deafness patients of Chinese minority and Han ethnicities in Yunnan, China.
abstract: BACKGROUND
  Each year in China, 30,000 babies are born with congenital hearing impairment. However, the molecular etiology of hearing impairment in the Yunnan Province population where more than 52 minorities live has not been thoroughly investigated. To provide appropriate genetic testing and counseling to these families, we investigated the molecular etiology of nonsyndromic deafness in this population.
  
  
  METHODS
  Unrelated students with hearing loss (n = 235) who attended Kunming Huaxia secondary specialized school in Yunnan enrolled in this study. Three prominent deafness-related genes, GJB2, SLC26A4 and mtDNA 12S rRNA, were analyzed. High-resolution temporal bone computed tomography (CT) scan examinations were performed in 100 cases, including 16 cases with SLC26A4 gene variants, and 37 minorities and 47 Han cases without any SLC26A4 gene mutation.
  
  
  RESULTS
  The GJB2 mutation was detected in 16.67% (7/42) of minority patients and 17.62% (34/193) of Chinese Han patients (P > 0.05). 235delC was the hotspot mutation in nonsyndromic hearing loss (NSHL) patients, whereas 35delG was not found. The 431_450del19 mutation was detected for the first time in Han NSHL patients, which resulted in a premature stop codon and changed the protein. The SLC26A4 mutation was found in 9.52% (4/42) of minority patients and 9.84% (19/193) of Han Chinese patients (P > 0.05). The frequencies of mtDNA 12S rRNA mutation in minority and Han Chinese patients were 11.90% (5/42) and 7.77% (15/193; P > 0.05), respectively. Sixteen (16/23, 69.57%) patients with SLC26A4 mutations received temporal bone CT scan, and 14 patients were diagnosed with enlarged vestibular aqueducts (EVAs); the other 2 patients had normal inner ear development. The ratio of EVA in the minorities was 14.63% (6/41).
  
  
  CONCLUSIONS
  In this study, a total of 35.74% deaf patients showed evidence of genetic involvement, based on either genetic screening or family history; 17.45%, 9.79%, and 8.51% of the patients were determined to have inherited hearing impairment caused by GJB2, SLC26A4, and mtDNA 1555A > G mutations. There was no significant difference in deafness associated gene mutational spectrum and frequency between the Yunnan minority and Han patients.
authors.forename: Feng
authors.initials: F
authors.lastname: Xin
authors.forename: Yongyi
authors.initials: Y
authors.lastname: Yuan
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Deng
authors.forename: Mingyu
authors.initials: M
authors.lastname: Han
authors.forename: Guojian
authors.initials: G
authors.lastname: Wang
authors.forename: Jiandong
authors.initials: J
authors.lastname: Zhao
authors.forename: Xue
authors.initials: X
authors.lastname: Gao
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.forename: Dongyi
authors.initials: D
authors.lastname: Han
authors.affiliation: Department of Otolaryngology and Genetic Testing Center for Deafness, Chinese PLA General Hospital, Beijing 100853, P,R, China. daipu301@vip.sina.com.
authors.forename: Pu
authors.initials: P
authors.lastname: Dai
mesh_terms: D000293:Adolescent; D000328:Adult; D002681:China; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D003638:Deafness / Q000208:ethnology / Q000235:genetics*; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008913:Minority Groups; D009154:Mutation; D000076988:Sulfate Transporters; D013701:Temporal Bone / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D017630:Connexins; D004272:DNA, Mitochondrial; C000607042:GJB2 protein, human; D026901:Membrane Transport Proteins; C085609:SLC26A4 protein, human; D000076988:Sulfate Transporters; D000072259:Connexin 26