Int J Pediatr Otorhinolaryngol 2009 Jan 22;73(1):103-7. Epub 2008 Nov 22.
Department of Oto-Rhino-Laryngology, University of Tartu, Tartu, Estonia.
Objective: The aim of our study was to identify the IVS2-2A>G sequence change in the SLC26A5 (Prestin) gene in Estonian individuals with hearing loss and in their family members.
Methods: In the years 2005-2007 we have screened 194 probands with early onset hearing loss and 68 family members with an arrayed primer extension (APEX) microarray, which covers 201 mutations in six nuclear genes (GJB2, GJB6, GJB3, GJA1, SLC26A4, SLC26A5) and two mitochondrial genes encoding 12S rRNA and tRNA-Ser (UCN).
Results: In four probands with early onset hearing loss and in five unaffected family members from five families we identified the IVS2-2A>G change in one allele of the SLC26A5 gene. We did not find any homozygosity for this splice variant. IVS2-2A>G was identified in 2.1% of probands. One of these probands, however, is also homozygous for the 35delG mutation in the GJB2 gene and a second patient has Down syndrome, which is also associated with hearing impairment. Therefore, in those two cases the etiology of the hearing loss is probably not associated with the IVS2-2A>G sequence change in the SLC26A5 gene.
Conclusion: Our data support the hypothesis that heterozygosity for the mutation IVS2-2A>G in SLC26A5 gene may not, by itself, be sufficient to cause hearing loss.