title: A systematic review and meta-analysis of 235delC mutation of GJB2 gene.
abstract: BACKGROUND
  The 235delC mutation of GJB2 gene is considered as a risk factor for the non-syndromic hearing loss (NSHL), and a significant difference in the frequency and distribution of the 235delC mutation has been described world widely.
  
  
  METHODS
  A systematic review was performed by means of a meta-analysis to evaluate the influence of the 235delC mutation on the risk of NSHL. A literature search in electronic databases using keywords "235delC", "GJB2" associated with "carrier frequency" was conducted to include all papers from January 1999 to June 2011. A total of 36 papers were included and there contained 13217 cases and 6521 controls derived from Oceania, American, Europe and Asian.
  
  
  RESULTS
  A remarkable heterogeneity between these studies was observed. The combined results of meta-analysis showed that the 235delC mutant increased the risk of NSHL (OR = 7.9, 95%CI 4.77 ~ 13.11, P <0.00001). Meanwhile, heterogeneity of genetic effect was also observed due to the ethnic specificity and regional disparity. Therefore, the stratified meta-analysis was subsequently conducted and the results indicated that the 235delC mutation was significantly correlated with the risk of NHSL in the East Asian and South-east Asian populations (OR = 12.05, 95%CI 8.33~17.44, P <0.00001), but not significantly in the Oceania and European populations (OR = 10.36, 95%CI: 4.68~22.96, Z = 1.68, P >0.05).
  
  
  CONCLUSIONS
  The 235delC mutation of GJB2 gene increased the risk of NHSL in the East Asian and South-east Asian populations, but non-significantly associated with the NSHL susceptibility in Oceania and European populations, suggesting a significant ethnic specificity of this NSHL-associated mutation.
authors: Department of Biotechnology, School of Basic Medical Science, Nanjing Medical University, Nanjing 210029, People’s Republic of China.
authors: Jun
authors: J
authors: Yao
authors: Yajie
authors: Y
authors: Lu
authors: Qinjun
authors: Q
authors: Wei
authors: Xin
authors: X
authors: Cao
authors: Guangqian
authors: G
authors: Xing
mesh_terms: D001208:Asia; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D017353:Gene Deletion; D006580:Genetic Carrier Screening; D034381:Hearing Loss / Q000235:genetics; D006801:Humans; D009154:Mutation
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26