[Phenotype of patients showing hearing impairment based on the 35delG mutation in the connexin 26 gene].
Hereditary hearing impairment constitutes a heterogeneous class of disorders showing different patterns of inheritance and involving multiple genes. Mutations in the GJB2 gene, especially the 35delG mutation, have been established as a major cause of inherited and sporadic nonsyndromic hearing impairment in different populations. We analyzed 14 northeast Hungarian families and 69 sporadic cases with nonsyndromic hearing impairment for the 35delG mutation. Sixty-five patients showing a homozygous 35delG mutation were examined regarding their audiologic phenotype. In general, these patients (70%) showed a prelingual, sensorineural, bilateral, symmetric hearing impairment without progression. The audiograms demonstrated sloping as well as flat patterns. The severity of hearing impairment varied in 30% of all analyzed patients, making genetic counseling difficult.