The identification of genes causing non-syndromic hearing impairment (ARNSHL) [http://dnalab-www.uia.ac.be/dnalab/hhh/] has partially resolved the puzzle of clinical and genetic heterogeneity of deafness (1).
Among these genes the gene with the most significant impact on the population genetics and genetic counselling is the GJB2 (connexin-26) gene with the mutation c.35delG that accounts for the majority of mutations in deaf Caucasians (2, 3). Studies published so far have reported the differences in frequency of the mutation in different populations, and its variability in clinical impact on hearing impairment (4, 5). The disorder is highly heterogeneous; every population has a unique HL etiologic profile dependent on ethnic, geographic, social and medical factors. Genetic factors contribute to up to 66% of Congenital hearing loss CHL cases in industrialized countries (6). The remaining 33% of cases can be ascribed to environmental and unidentified genetic factors. At least 400 genetic loci are associated with syndromic and over 150 genetic loci are …show more content…
Research into the genetics of deafness has shown that mutations in the CX26 gene, located on human chromosome 13q11, cause non-syndromic recessive deafness (9, 10). Expression of GJB2 has been documented in a variety of cells and tissues. In the cochlea, CX26-containing gap junctions are proposed to maintain K homeostasis by ferrying K away from the hair cells during auditory transduction(11). Recently, it has been shown that the intercellular transduction of the second messenger inositol triphosphate (IP3) is also essential for the perception of sound (12). Moreover, specific Cx26 deletion in Deiters cells and outer pillar cells in mice produces hearing disorder due to a loss of high frequency response as an effect at reduction of signal reinforcement (13). Similar findings were detected in mice
Among these genes the gene with the most significant impact on the population genetics and genetic counselling is the GJB2 (connexin-26) gene with the mutation c.35delG that accounts for the majority of mutations in deaf Caucasians (2, 3). Studies published so far have reported the differences in frequency of the mutation in different populations, and its variability in clinical impact on hearing impairment (4, 5). The disorder is highly heterogeneous; every population has a unique HL etiologic profile dependent on ethnic, geographic, social and medical factors. Genetic factors contribute to up to 66% of Congenital hearing loss CHL cases in industrialized countries (6). The remaining 33% of cases can be ascribed to environmental and unidentified genetic factors. At least 400 genetic loci are associated with syndromic and over 150 genetic loci are …show more content…
Research into the genetics of deafness has shown that mutations in the CX26 gene, located on human chromosome 13q11, cause non-syndromic recessive deafness (9, 10). Expression of GJB2 has been documented in a variety of cells and tissues. In the cochlea, CX26-containing gap junctions are proposed to maintain K homeostasis by ferrying K away from the hair cells during auditory transduction(11). Recently, it has been shown that the intercellular transduction of the second messenger inositol triphosphate (IP3) is also essential for the perception of sound (12). Moreover, specific Cx26 deletion in Deiters cells and outer pillar cells in mice produces hearing disorder due to a loss of high frequency response as an effect at reduction of signal reinforcement (13). Similar findings were detected in mice