They can hear well up to about forty years old, but then suddenly deafness strikes people with DFNA9. The cells of the inner ear can no longer reverse the damage caused by a genetic defect in their DNA. Researchers at Radboud university medical center have now developed a “genetic patch” for this type of hereditary deafness, with which they can eliminate the problems in the hearing cells. Further research in animals and humans is needed to bring the genetic patch to the clinic as a therapy.