Objective: Hearing loss is the most common form of sensory impairment, with approximately one infant/1000 born with profound congenital deafness. A pre-lingual bilateral sensorineural hearing impairment poses a substantial problem as it negatively impacts on the subject's ability to conduct a normal social life. The aim of the study was to observe, in a group of children affected by pre-lingual non-syndromic autosomal recessive hearing impairment: (1) the role of the possible mutation of connexin 26 in the pathogenesis of the hearing loss; (2) the audiological and clinical aspects of the hearing impairment; (3) therapy to be adopted for the different patients.
Methods: The study was carried out on 39 patients, 16 males and 23 females, aged between six and 17 years (mean 12 years), affected by non syndromic congenital deafness, presumably hereditary, referred to the out-patients audiology clinic for children of the Department of Otolaryngology of the Federico II University of Naples.
Results: Our study conducted on 39 children with pre-lingual bilateral sensorineural autosomal recessive deafness showed as follows: (I) from a molecular perspective: an incidence of 41% in the cases studied of mutations in the encoding of the connexin 26 gene; a prevalence in our case study of the 35delG mutation (69%). (II) The characteristics of the hearing impairments in the children studied were homogeneous, regardless of the presence or absence of a connexin 26 mutation: the hearing impairment was pre-lingual bilateral sensorineural, the impairment often involved mainly the high frequencies, but, especially in the severe forms an involvement of all the frequencies was not rare; the hearing impairments were symmetrical and non progressive in time. (III) The results of the application of prosthesis and thereafter rehabilitative language therapy are generally satisfactory but correlated of course to the severity of the hearing loss.
Conclusion: In conclusion, we hope that further developments in the research on genetic hearing impairments will promptly result in advances in clinical practice.