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Reversing Connexin 30 Hearing Loss
Genetic hearing loss may be reversible by compensating for a missing protein, according to research on mouse models at Emory University.
In mice, increasing the amount of the protein Connexin 26 in the cochlea compensates for the absence of another protein, Connexin 30, according to research by Xi (Erick) Lin, associate professor of otolaryngology and cell biology at Emory University School of Medicine, and colleagues, published in the Jan. 23, 2007, issue of the Proceedings of the National Academy of Sciences.
The findings come a decade after scientists first discovered that mutations in genes coding for Connexin 26 and/or Connexin 30 are linked to approximately half of all cases of human autosomal nonsyndromic prelingual deafness.
In people without congenital hearing loss, Connexin 26 and Connexin 30 work together to form the cochlea's hybrid gap junctions, which facilitate intercellular communication. But when one of the proteins is missing, the hybrid junction gaps fail to work, causing cochlear hair cell death and leaving the cochlea incapable of translating sounds into nerve impulses.
Lin's research team discovered that by adding extra Connexin 26 to mice that were missing Connexin 30, hearing sensitivity was restored and the expected hair cell death never occurred. Those findings led Lin to conclude that the hearing loss is simply caused by not having enough protein remaining in the ear of these mutant mice to assemble gap junctions.
As research increases, these results—and future findings—may mean changes in treatment of congenital hearing loss. The research team's findings indicate that a drug to boost Connexin 26 may be all that is needed. The study was funded by the National Institute on Deafness and Other Communication Disorders, the Woodruff Foundation, the Deafness Research Foundation and the National Organization for Hearing Research. Find the journal abstract on PNAS's Web site.
Children With Hearing Loss and Meningitis Risk
Children who have severe hearing loss are five times more likely to contract meningitis, according to a new study published in the March 2007 issue of Otolaryngology-Head and Neck Surgery.
The large-scale, nine-year study monitored 663,963 children born in Denmark between 1995 and 2004. It identified 39 children with both hearing loss and meningitis; of these children, five were first diagnosed with hearing loss, and later, meningitis. Statistically, the authors determined the likelihood of a child developing meningitis after acquiring hearing loss is five times that of other children.
According to the authors, the research provides evidence of an association between hearing loss and the onset of meningitis, providing physicians and parents with ample reason to be mindful of possible signs and symptoms of meningitis and to consider vaccination as a preventive step. Information about the study is available on Medical News Today's Web site.
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