title: [Analysis of GJB2 gene coding sequence in patients with nonsyndromic hearing loss].
abstract: OBJECTIVE
  To analyze the coding sequence of GJB2 gene in six pedigrees with nonsyndromic hearing loss in order to find deafness-causing mutations in the GJB2 gene, and to explore the inherent pattern of deafness-causing mutations in the GJB2 gene.
  
  
  METHODS
  Genomic DNA was extracted from peripheral blood for the probands and their family members. Coding sequence of the GJB2 gene was amplified by polymerase chain reaction, sequence variations were determined by DNA sequencing. Amplified fragments with overlapping peaks on sequencing chromatogram were sequenced by TA cloning in order to determine whether the mutations originated from the same allele.
  
  
  RESULTS
  Mutations in the GJB2 gene were found in 4 out of the 6 pedigrees with nonsyndromic hearing loss. Four types of mutations were detected in the GJB2 gene, which were 235delC, 299-300delAT, 79G>A+341A>G, and 109G>A. Compound heterozygous polymorphisms 79G>A and 341A>G, and mutations 109G>A and 235delC had deafness-causing effects.
  
  
  CONCLUSIONS
  Heterogeneous mutations of the GJB2 gene are frequently seen in patients with nonsyndromic hearing loss. Sometimes, polymorphisms may cause deafness when they are combined. Environmental factors and other genes may contribute to hearing loss caused by the GJB2 gene mutations.
authors.affiliation: Department of Clinical Laboratory, People's Hospital of Baoan, Shenzhen, Guangdong 518101, P. R. China. shunchangsun@yahoo.com.cn
authors.forename: Shun-chang
authors.initials: SC
authors.lastname: Sun
authors.forename: Yi-xin
authors.initials: YX
authors.lastname: Liu
authors.forename: Yun-sheng
authors.initials: YS
authors.lastname: Peng
authors.forename: Hai-fei
authors.initials: HF
authors.lastname: Li
authors.forename: Chun-ying
authors.initials: CY
authors.lastname: Xie
mesh_terms: D001483:Base Sequence; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D034381:Hearing Loss / Q000235:genetics*; D006801:Humans; D040582:Inheritance Patterns / Q000235:genetics; D008297:Male; D010375:Pedigree
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26