Researchers develop a genetic patch to prevent hereditary deafness
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.
Hereditary deafness can manifest itself in different ways. Often the hereditary defect (mutation) immediately causes deafness from birth. Sometimes, as with DFNA9, you experience the initial problems in hearing after forty, fifty, sixty years. This has everything to do with the way DFNA9 mechanistically works. Every person gets half of his genes from his father and the other half from his mother. If you have two healthy copies of the DFNA9 gene, your inner ear works normal. If you receive a mutated copy of the gene from either your father or mother, deafness will develop later in life.
Erik de Vrieze and Erwin van Wijk, both researchers at Hearing & Genes of the department of Ear, Nose and Throat, have conducted extensive research into the condition. De Vrieze: “We now know that you actually produce enough of the associated DFNA9 protein with just one healthy gene copy to be able to hear well for life. But there is a catch with this condition. The mutated protein is, in a way, disturbing the function of the healthy protein. It sticks to it, so that the healthy protein can also no longer do its job.
This clumped protein spaghetti is constantly being removed by the cells of the inner ear, but after decades the clean-up service in these cells is reaching its limit and can no longer cope with these protein clumps. A threshold value is exceeded. As a result, the waste accumulates, the hearing cells start to function poorly and even die over time. After years of normal hearing, DFNA9 patients suddenly notice that their hearing is deteriorating, and sometimes deteriorating very quickly. Until at some point they will become deaf. “
Enough time for treatment
The specific DFNA9 mutation seems to originate from a common ancestor in the Southern Netherlands, somewhere at the end of the Middle Ages. This can more or less be deduced from the spread of the fairly unique clinical manifestation, which is now estimated to occur in about 1500 people in the (southern) Netherlands and Belgium. Perhaps even more important than the origin of the disease is whether or not anything can be done about it.
This condition has two favorable characteristics for therapy development. Firstly, it is a hereditary condition that only manifests itself after a few decades in life. In case an effective treatment will become available for this disease, a sufficiently large timeframe is available to apply it before the hearing loss really…