NIDCD scientists have demonstrated that a specific mutation in mitochondrial DNA is a cause of deafness. While most DNA is found in the cell nucleus, DNA can also be found in the mitochondria, the energy-generating structures inside cells. This discovery is based on a study of a large North American family with maternally inherited deafness and is published in the January 2008 issue of Clinical Genetics.
Experts estimate that genetic factors cause 50-60 percent of severe to profound childhood hearing loss in developed countries. Mitochondrial DNA carries genes that have been linked to hearing loss, heart disease, nerve damage, and epilepsy. Unlike DNA in the nucleus, which is inherited from both parents, mitochondrial DNA is passed only from mother to child.
These results will improve the genetic counseling of individuals with hearing loss after genetic testing. The mutated gene also provides researchers with clues that, with further research, could lead to drugs for treating deafness.
