GJB2 gene mutation

Congenital hearing loss (CHL) is diagnosed in 1 – 2 newborns in 1000, genetic factors contribute to two thirds of CHL cases in industrialised countries. Mutations of the GJB2 gene located in the DFNB1 locus (13q11-12) are a major cause of CHL worldwide.

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GJB2 encodes connexin 26, a gap junction protein that is assumed to be a component of the potassium recycling pathway in the inner ear. Loss or malfunction of these gap junctions, as might be refl ected by mutations in GJB2, may disrupt potassium movement from the hair cells through the supporting cell network to the endolymph, leading to hearing impairment.

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The contribution of genetics to presbycusis (see below) is also becoming better understood. In addition to GJB2, several other nonsyndromic genes are associated with hearing loss that progresses with age. Sensitivity to aminoglycoside ototoxicity can be maternally transmitted through a mitochondrial mutation. Susceptibility to noise-induced hearing loss may also be genetically determined. There are 400 syndromic forms of hearing loss.

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