Questions about project Zebrafish

Q: There are several genetic mutations causing Usher syndrome type 2. Does the gene therapeutic research project Zebrafish apply to all mutations of Usher syndrome type 2?

This research initially focusses on a small select group of people with a specific mutation in the USH2A gene. If successful, the method can be developed and tested for other USH2A mutations and mutations in other Usher genes.

Q: There are several research projects concerning the treatment of Usher syndrome (for instance stem cell therapy). In what way does this therapy distinguish itself?

To our knowledge there is currently no therapy in development for Usher syndrome type 2A. At the moment the large size of the USH2A gene restricts the possibility of gene replacement therapy. This project tries to overcome this problem by using a different approach.

Q: In the United States the first trials of gene therapy for patients with Usher type 1B are in an advanced stage. Is this gene therapy also possible for people with Usher syndrome type 2 and 3?

The USH1B gene is small enough to be packaged within current viral vectors used to deliver the genes to the appropriate cells in the retina. The USH2A gene is so large it can’t be packaged within the viruses. So a similar strategy as used in Usher syndrome type 1B (which is in an advance state of development) is not possible for Usher syndrome type 2A.

Q: This research project is currently looking for funds with this campaign. Does this mean there isn’t any research into Usher syndrome at the moment?

In a number of laboratories all over the world several researches are trying to clarify the cause and/or the mechanism of action of Usher syndrome. They are all looking for ways of funding. However, so much money is needed for all this research, other ways of finding funds is necessary. This current campaign gives patients important tools to speed up the aid in development of treatment methods.

Q: Can gene therapy lead to a halt of deterioration in hearing?

Current focus of this project is on halting progression of loss of sight and this does not include hearing. Whether the same approach of the inner ear will sort the same effect is difficult to predict and needs to be seen in the future.

Q: Is there hope for any improvement in sight?

First the aim is to stop further deterioration, but there is hope a slight improvement is possible with further research.

Q: Can this research project only start when funds are sufficient?

The sum necessary is based on appointing one researcher on a research project for the duration of 3 years. It is possible to start when sufficient funds are available covering the first year. When more money is available, more researchers can be appointed and results can be expected even sooner.

Q: I would like to participate in the first trials. Where do I sign up?

Register through the available email address at Radboudumc: Please take into account it may take some time before first trials start. In the meantime an assessment is needed to ensure you meet all the required criteria. For this your gene mutation needs to be known and match this project, your clinical data concerning the progression of your sight and hearing over a longer period (2-3 years) needs to be assessed and stored in a database as described in another project proposal, which also requires considerable funding.

Q: It is said it may take 5 years before first trials start in the hospital. Can this procedure be shortened? (meaning can this be influenced?)

Time necessary to prepare for the start of a clinical trial (identification of patients, legislation and authorization, funding assisted by an industrial partner, assessing the natural course of the syndrome) is at least 3 to 5 years. This can’t be cut short. However, if in a shorter period of time a lot of extra funds become available, it is possible to begin development of a therapy for patients with other mutations in the USH2A gene or even in other Usher genes.

Q: I have Usher syndrome type 1, meaning another gene mutation then Usher syndrome type 2A. How can this gene therapy be beneficial for me too?

If this method works for (specific) mutations in the USH2A gene, there is a real chance this might work for other Usher genes too. Further research is needed to find out.

Q: I do not have a hearing problem, but I do have tunnel vision caused by Retinitis Pigmentosa (RP) and I do have Usher syndrome. Could this possible gene therapy apply to me too?

If your Retinitis Pigmentosa is caused by mutations in the USH2A gene, then this form of therapy could indeed possibly be used. This would depend on the type of gene you carry. Also, added research might explain why some people have no or minimal hearing loss.

Q: What is the procedure in calling participants of the first trials?

Usher syndrome is a rare disorder. To identify suitable candidates for the first trials,databases will be searched globally for registered Usher patients. Hence the importance of registering as many people with Usher syndrome as possible in the Usher registry or registering at:

Q: I think I might have Usher syndrome, but I’ve never had it checked. Do I qualify for this trial?

It is important to first find out which genetic mutation you have. In The Netherlands you can do this at any university hospital near you. Or email your question at:

Q: Is it possible for people living outside The Netherlands to sign up?

People with Usher syndrome who live outside The Netherlands can also sign up for these research projects. For this email:

Q: For years it has been tried to find my genetic mutation in vain. Still I have all clinical symptoms of Usher syndrome. Can I still sign up for these trials?

A genetic mutation must be known before you possibly qualify for participation in these clinical trials. Furthermore this mutation must match therapeutic developments at that time. So for you it is also important to go to a university medical center near you or to email your question at

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