Hearing loss associated with 35delG mutation in Connexin-26 (GJB2) gene: audiogram analysis
Fabrizio Salvinelli a1, Manuele Casale a1, Luca D’Ascanio a1, Luca Firrisi a1, Fabio Greco a1andAlfonso Baldi a2 a1 Area of Otolaryngology, University Campus Bio-Medico, Rome,Italy. a2 Department of Biochemistry and Biophysic, “F. Cedrangolo”, Section of Anatomic Pathology, Second University of Naples, Naples,Italy.
35delG is the most common mutation in the Connexin-26 gene, representing a major cause of autosomal recessive hearing loss. The aim of this study was to evaluate the relationship between the audiological phenotype and the 35delG mutation in 64 Sicilians with non-syndromic deafness. Pure-tone audiometry and a screening for 35delG mutation were performed. Audiograms were evaluated according to the classification of Liu and Xu. Thirteen homozygotes and nine heterozygotes for the investigated mutation were found. Symmetrical hearing loss was significantly (p=0.008) more common in homozygous subjects than in those without the Connexin-26 mutation. Profound-severe hypoacusia was found in 92.3 per cent of 35delG homozygous, 22.3 per cent of heterozygous and 58.7 per cent of 35delG absent patients. Residual shape audiograms were more frequent in homozygotes. A molecular analysis for the 35delG mutation should be performed in cases of symmetric, severe-profound congenital hearing loss, as a genetic cause is probable in such cases.