title: [Progressive hearing impairment with deletion in GJB2 gene despite normal newborn hearing screening].
abstract: OBJECTIVE
  Hearing impairment is the most common sensorineural disease in humans. About 1-3 per 1 000 neonates suffers at birth or in the first years from high-grade to severe hearing impairment. About half of the cases are due to genetic alterations. Most commonly, the GJB2 gene (connexin-26) is concerned with the mutation c.35delG. MATERIAL AND METHODES: All patients showed a severe to profound hearing impairment to the course. DNA isolation, amplification and sequencing was performed using standard techniques.
  
  
  RESULTS
  In the studied patient population we have 142 pa-tients with a homozygous deletion mutation in GJB2 gene (c.35delG) and 29 patients who are heterozygous for this mutation on one allele and heterozygous for another loss-of-function mutation in GJB2 gene. Of these 171 patients were 16 (9.3%) on an inconspicuous newborn hearing screening using Otoacoustic Emissions (OAE). Total was observed a progression of hearing impairment in 31 of these patients (18.1%).
  
  
  CONCLUSIONS
  This fact suggests that homozygous deletion mutation c.35delG does not always contribute to an congenital hearing impairment, but to a progressive hearing loss that might develop over the first months and years of life. Additionally, we have to re-evaluate the value of OAE for newborn hearing screening, keeping in mind that one positive result is no warranty for a normal development of hearing function, but a result that should be checked in the course. We recommend annual hearing tests to the paediatrician and with a known familial hearing loss and other risk factors pedaudiological controls.
authors.affiliation: Universitätsklinikum für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Freiburg.
authors.forename: N
authors.initials: N
authors.lastname: Prera
authors.affiliation: Universitätsklinikum für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Freiburg.
authors.forename: E
authors.initials: E
authors.lastname: Löhle
authors.affiliation: Universitätsklinikum für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum Freiburg.
authors.forename: R
authors.initials: R
authors.lastname: Birkenhäger
mesh_terms: D017668:Age of Onset; D000483:Alleles; D002675:Child, Preschool; D019929:Cochlear Implantation; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003638:Deafness / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D057210:Delayed Diagnosis; D018450:Disease Progression; D006580:Genetic Carrier Screening; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015997:Neonatal Screening; D017084:Otoacoustic Emissions, Spontaneous / Q000235:genetics*; D011237:Predictive Value of Tests; D017384:Sequence Deletion / Q000235:genetics*
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26