Molecular investigation in children candidates and submitted to cochlear implantation.
OBJECTIVE
Recent progresses in molecular biology have been made in the diagnosis of sensorineural hearing loss. The high prevalence of a connexin 26 gene mutation, and its easy identification have made the diagnosis possible. The most frequent gene mutation is called 35delG. The purpose of this study was to evaluate the prevalence of 35delG mutation in children submitted to cochlear implantation who had severe and profound hearing loss previously diagnosed as idiopathic.


METHODS
The study was done at the Cochlear Implantation Clinic of the Otolaryngology Department and at the Laboratório Genética Humana-CBMEG, UNICAMP-SP. 32 children with severe to profound sensorineural hearing loss were evaluated. The detection of the 35delG mutation was made by a allele-specific PCR, using primers and polymerase chain reaction.


RESULTS
69% had a normal exam, 12% were homozygous for the mutation, 19% of the cases were heterozygous. The 35delG mutation in heterozygous is not a cause of hearing loss.


CONCLUSIONS
The data confirm the high prevalence of the 35delG mutation in nonsyndromic bilateral profound sensorineural hearing loss. It was also possible to diagnose the cause of hearing loss as genetic in a significant percentage of patients. That stresses the importance of the molecular investigation in those cases formerly classified as idiopathic.
Bernardes
Raquel
R
Cochlear Implant Program, Department of Otorhinolaryngology/Head and Neck Surgery, UNICAMP, Brazil.
Bortoncello
Silvana
S
Christiani
Thalita Vitachi
TV
Sartorato
Edi Lúcia
EL
Silva
Rodrigo César e
RC
Porto
Paulo R Cantanhede
PR
D002648:Child; D019929:Cochlear Implantation; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D006312:Hearing Loss, Bilateral / Q000235:genetics*; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D009154:Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012720:Severity of Illness Index
D017630:Connexins; D000072259:Connexin 26