title: Prevalence of mutations located at the dfnb1 locus in a population of cochlear implanted children in eastern Romania.
abstract: OBJECTIVE
  Hearing loss is one of the major public health problems, with a genetic etiology in more than 60% of cases. Connexin 26 and connexin 30 mutations are the most prevalent causes of deafness. The aim of this study is to characterize and to establish the prevalence of the GJB2 and GJB6 gene mutations in a population of cochlear implanted recipients from Eastern Romania, this being the first report of this type in our country.
  
  
  METHODS
  We present a retrospective study that enrolled 45 Caucasian cochlear implanted patients with non-syndromic sensorineural severe to profound, congenital or progressive with early-onset idiopathic hearing loss. We performed sequential analysis of exon 1 and the coding exon 2 of the GJB2 gene including also the splice sites and analysis of the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343-19,968,698).
  
  
  RESULTS
  The genetic analysis of the GJB2 gene identified connexin 26 mutations in 22 patients out of 45 (12 homozygous for c.35delG, 6 compound heterozygous and 4 with mutations only on one allele). We found 6 different mutations, the most prevalent being c.35delG - found on 32 alleles, followed by p.W24* - found on 2 alleles. We did not identify the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343-19,968,698).
  
  
  CONCLUSIONS
  Although the most prevalent mutation was c.35delG (80% from all types of mutations), unexpectedly we identified 5 more different mutations. The presence of 6 different mutations on the GJB2 gene has implications in hearing screening programs development in our region and in genetic counseling.
authors: University of Medicine and Pharmacy Gr. T. Popa, Iaşi, Romania. lmradulescu@yahoo.com
authors: Luminiţa
authors: L
authors: Rădulescu
authors: Cristian
authors: C
authors: Mârţu
authors: Ralf
authors: R
authors: Birkenhäger
authors: Sebastian
authors: S
authors: Cozma
authors: Loreta
authors: L
authors: Ungureanu
authors: Roland
authors: R
authors: Laszig
mesh_terms: D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation / Q000379:methods; D003054:Cochlear Implants; D015331:Cohort Studies; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D005817:Genetic Counseling; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology / Q000235:genetics* / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009154:Mutation / Q000235:genetics*; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D012383:Romania / Q000453:epidemiology
chemical_list: D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26