Who cleans up ‘the mess’ from the cones?

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New research on the cause of blindness due to Usher syndrome

A research team led by Dr. Ronald Roepman (www.roepmanlab.com) is conducting research at Radboudumc, Netherlands, to investigate the underlying cause of vision loss in Usher syndrome. In this study, titled “Harnessing Autophagy to Combat Macular Degeneration,” they aim to gain more clarity on the death of cone cells in the retina. In a healthy eye, waste products in the retina are “cleaned up,” but in retinal diseases like Usher syndrome, this process is insufficient. The cones ultimately die because waste accumulates in harmful quantities within these cells. Thanks to the efforts of the participants in ‘Nederland wandelt voor Usher’ (Event Walks for Usher), Stichting Ushersyndroom (the Dutch Usher Syndrome Foundation) can finance a significant portion of this important research.

Crucial discovery
Hereditary blindness is a profound condition that seriously affects the lives of many patients. Researchers have been searching for effective treatments for some time, but the question of why waste products in the retina are not cleared in hereditary retinal diseases has remained unknown until now. Dr. Ronald Roepman, who collaborates in this promising project with Dr. Erik de Vrieze and Dr. Erwin van Wyk, recently made a crucial discovery that may provide an answer to this question. This could be a significant step toward a solution. Dr. Ronald Roepman says, “If you understand why the cones don’t clean up the waste, then you might be able to help them clean it up, perhaps with medication.”

Autophagy
The research focuses on understanding the mechanism of ‘autophagy’ in cone cells. Autophagy is a biological process in which certain components of a cell, such as damaged proteins or foreign particles, are broken down. Recent research data suggest that dysregulation of this process is a significant cause of cone cell death, leading to progressive vision loss in hereditary retinal disorders.

Death due to self-waste
An Usher gene contains instructions for producing a protein that keeps the light-sensitive cells in the retina – the rods and cones – healthy. Errors in this gene can lead to the protein’s malfunction and disrupt the processes. Cones produce substantial amounts of waste products, which are normally cleared through the autophagy process. If the Usher proteins are absent or not functioning properly, the cones cannot dispose of their waste products and essentially drown in their own ‘mess.’ The researchers aim to determine how the genetic defect is responsible for the malfunctioning autophagy.

Zebrafish and retinal organoids
The research team uses zebrafish as a model organism in the laboratory due to the striking similarities between their eyes and those of humans. They will compare healthy cone cells with cone cells displaying disrupted autophagy using zebrafish. Additionally, the research team will use retinal organoids, small retinas grown in the laboratory using cells from both Usher syndrome patients and people with healthy eyes. These organoids provide a valuable platform to study the autophagy mechanism in healthy and diseased cells.

Hope for finding a safe and effective treatment
Once the autophagy mechanism is understood, the research team will search for substances that can stimulate the autophagy process, thereby reducing or preventing cone cell death. With the help of a database containing thousands of substances known to stimulate or inhibit proteins, they hope to find a safe and effective treatment.

Also, for other hereditary retinal diseases
This promising research will not only contribute to detailed knowledge about autophagy and cone cell death but also offer possibilities for further treatment development. If the results of this research prove successful, this project could slow down vision deterioration and have a significant impact on the quality of life for Usher syndrome patients. Dr. Roepman says, “It could offer a solution not only for Usher syndrome but also for patients with Retinitis Pigmentosa (RP), Macular Degeneration (MD), and all other forms of hereditary retinal diseases.”

The current project has a duration of three years. Stichting Ushersyndroom plays a significant role in the research by financing a large portion of the required budget. We are not the sole financiers of this research. Thanks to the L.S.B.S. (National Foundation for the Blind and Visually Impaired) and the donors of the Oogfonds (Dutch Eye Foundation), they are co-funders for this project, providing a valuable financial contribution to make this promising research possible.

The voucher was presented during the festive day at the Railway Museum in Utrecht on Global Usher Awareness Day 2023.

You can support us through a donation. With your contribution, the Stichting Ushersyndroom can finance scientific research. Research aimed at finding a treatment for Usher syndrome, so that becoming deaf and blind can be halted!

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Every donation is valuable and brings us closer to solutions for Usher syndrome.

The very first adgrv1-zebrafish model has been presented!

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Recently, an article was published in the journal Cells about the scientific research on USH2C. Merel Stemerdink and her colleagues at the Radboudumc have developed a zebrafish model with a gene defect in adgrv1 (the gene associated with USH2C). This is the very first animal model for ADGRV1-associated retinal dysfunction, and therefore a crucial step to enable further research on therapy development for ADGRV1-related RP.

Merel Stemerdink (right) has developed the mini gene products and shows them to Ivonne Bressers (Stichting Ushersyndroom). Ivonne (left) looks at the PCR strip in her hand.

Using these fish as an animal model, Merel will also start testing the effectiveness of the ADGRV1-minigene therapy in the coming year.

The official title of the paper is ‘Generation and Characterization of a Zebrafish Model for ADGRV1-Associated Retinal Dysfunction Using CRISPR/Cas9 Genome Editing Technology’ and it has been published in a Special Issue of Cells titled ‘CRISPR-Based Genome Editing in Translational Research’.

 

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Sleep problems Usher patient appears to be a hallmark feature of the disease

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Vision impairment is not the driver of fatigue and sleep problems

It was always thought that fatigue and sleep problems in patients with Usher syndrome are the result of increased efforts to compensate for their dual sensory impairment: limited vision combined with hearing loss. Researchers from Radboudumc show in Ophthalmology Science that this idea is incomplete. Besides severe problems with hearing and vision, sleep problems also seem to be a hallmark feature of the disease.

Patients with Usher syndrome experience major problems with vision and hearing. They are born profound deaf or hearing impaired and around puberty they also start to slowly lose their eyesight. These are the central features of the disease. The large individual differences in disease severity and progression are closely related to the underlying genetic defect and the type of Usher syndrome. “Besides hearing and vision loss, patients occasionally also encounter some other problems, like balance deficits, but these have been recognized as part of the disease,” says researcher Erwin van Wijk. “In addition, sleep problems and excessive fatigue are also regularly reported in the consulting room. The fatigue has always been regarded as a result of the dual sensory impairment that patients have to deal with. It’s generally assumed that the sleep problems often reported by patients are the result of their impaired light perception. After all, individuals with poor light perception gradually lose visual day and night rhythms, having a significant impact on their sleep quality.”

Poor sleep
Researchers at Radboudumc are in close contact with patients, mainly via the Dutch Ushersyndrome Foundation. “At one point we noticed that very many patients complained about sleep problems and fatigue”, says Van Wijk. “That intrigued us. Was perhaps something else going on than we always anticipated? Under supervision of Erik de Vrieze, Juriaan Metz, Rob Collin and myself, PhD student Jessie Hendricks started a survey to further investigate this. Fifty-six Usher syndrome type 2A (USH2A) patients and 120 healthy controls were subjected to a set of five validated questionnaires to assess sleep quality, sleep disorders, fatigue, daytime sleepiness and chronotype.” The results indicated that USH2A patients indeed experienced a strongly reduced sleep quality and that they were more often sleepy and tired during the day as compared to controls. But most strikingly, their sleep problems were not related to the severity of their visual impairment. Van Wijk: “These findings perfectly matched the reports of several parents of young USH2A patients, but that were never given a proper follow-up.”

Hallmark feature of Usher syndrome
At a first glance, it may seem only a gradual difference, but the finding is much more significant. Van Wijk: “Actually, it means that the ubiquitously reported sleep problems by USH2A patients are not primarily due to impaired light perception, but that these problems already exist in patients who still have a near normal eyesight. Sleep problems should therefore probably be considered as an additional hallmark feature of Usher syndrome, and not as a consequence of poor or deteriorating eyesight.” Of course, this conclusion based on questionnaires, needs further substantiation. This can be done, for example, through research in an existing zebrafish model for Usher syndrome. Zebrafish also have a distinct sleep pattern. Is it also disturbed? And is there evidence in the brain that Usher syndrome-associated proteins are somehow involved in regulating sleep? These research questions are currently being followed-up.

Improvement in quality of life
Van Wijk points out another aspect of the research. If sleep problems indeed turn out to be part of the disease, there might be a possibility to treat these problems. “Currently, sleep problems are not included in the daily care for Usher syndrome patients, because it is not yet being recognized as a hallmark feature of the disorder. As a result, the visit to a sleep clinic is often not reimbursed by health insurance companies. This hopefully changes based on the study published in Ophthalmology Science and the follow-up studies that are currently being conducted. Treatment of sleep problems will be a major step forward in improving the quality of life of Usher syndrome patients.”

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Paper in Ophthalmology Science: Evaluation of sleep quality and fatigue in patients with Usher syndrome type 2a – Jessie M. Hendricks, MSc, Juriaan R. Metz, Hedwig M. Velde, Jack Weeda, Franca Hartgers, Suzanne Yzer, Carel B. Hoyng, Ronald J.E. Pennings, Rob W.J. Collin, H. Myrthe Boss, Erik de Vrieze, Erwin van Wijk

Does this mutation cause blindness? It does, doesn’t, does!

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Janine Reurink ends long lasted controversy with major implications for healthcare


Initially there was no doubt a specific mutation in the USH2A gene caused the eye disease retinitis pigmentosa. Spanish research undermined that clarity and left patients in limbo. Until new research by PhD candidate Janine Reurink made it abundantly clear that the cause is indeed to be found in that USH2A gene. A textbook example of science in action.

We know of ten different genes that can cause Usher syndrome if they contain a mutation. Mutations in these genes eventually lead to deafness and blindness in patients with Usher syndrome. Mutations in Usher genes sometimes ‘generate’ other disorders as well. For example, a specific mutation in the Usher2A gene (USH2A) causes the eye disease retinitis pigmentosa (RP) when inherited from both father and mother. This mutation causes one spot in the USH2A protein to change the amino acid cysteine to phenylalanine, another amino acid. All this was genetically and clinically fine-tuned at the end of the last century. If you had such a specific double mutation in the USH2A gene, you didn’t have Usher syndrome but RP and the clinical problems were limited to blindness.

Smoldering controversy
Then suddenly a publication appeared about a Spanish family with RP. It wrote that researchers had found two individuals with exactly those specific USH2A mutations. But without any vision problem, which after all is an essential characteristic of RP! Erwin van Wijk, who has been researching Usher syndrome at the Radboudumc for over more than ten years: “That caused rather a lot of commotion among researchers and patients, because it meant this specific mutation could not be the cause of RP! Everyone who had previously received this diagnosis had apparently been misdiagnosed. So the real cause had to be found somewhere else in the genes.”
The publication causes many clinical genetics centers around the world to stop diagnosing RP on the basis of this USH2A mutation and all these patients should actually be re-screened. This also applies to Nijmegen. In the meantime, doubts continued. Was the screening in this Spanish family complete and reliable enough? – the results were never confirmed in any other study. Requests from different research groups to check the DNA of those families were not granted. Thus, a smoldering controversy about the value of the Spanish research ensued..

No alternatives mutations found
In recent years, Van Wijk and colleagues developed a promising therapy for a number of mutations in Usher genes. This therapy is based on a technique in which a piece of the RNA is ‘taped off’ (exon skipping). This prevents the mutation from being read and creates a protein that once again functions properly. These therapeutic ‘genetic patches’ can also be used for the specific USH2A mutation, but based on the Spanish family research the causal link with the eye disease is being questioned. As long as it’s unclear whether or not this mutation causes RP, no health insurance company will ever reimburse such a therapy. So a conclusive answer is needed. That proof was exactly what Janine Reurink set out to provide as part of her doctoral research.
Reurink: “First of all, we looked at several patients with the USH2A mutation to see if another explanation could be found for the disorder. To do this, we mapped their entire genome and examined it on all sides. The result? We did not find any alternative genetic explanation. Based on our research, the USH2A mutation remains the only possible explanation.”

Crystal clear evidence
In Nijmegen, much Usher research is done in zebrafish. This time it was also used for additional research, looking for as much evidence as possible. Reurink: “With the CRISPR/Cas9 system, a molecular scissors with which pieces of DNA can be very precisely cut away and replaced, we made a zebrafish with exactly the same mutation as in humans. Analysis of retinal cells in the eye of these fish showed that the corresponding proteins are then no longer or hardly produced. Normal production is really very thoroughly disturbed by the mutation. What’s more: as a result, other essential proteins for vision no longer end up in the right places. We also made an ERG, a kind of brain film for the eye. It demonstrated with crystal clarity that vision is really affected in zebrafish with this mutation. In short, extensive genetic bio-molecular and functional research clearly shows that the USH2A mutation is indeed the underlying cause of this form of retinitis pigmentosa. In terms of a detective novel, we now really have tracked down the culprit.”

Impact on healthcare
The research by Reurink and colleagues has been published in NPJ Genomic Medicine. For people with RP with a USH2A mutation, it’s clear now that this is the real causative, pathogenic mutation. Further search for a (non-existent) cause is no longer necessary. Meanwhile, the clinical genetics laboratories at Radboudumc have adjusted their diagnostics accordingly. Something that many more laboratories worldwide are likely to do in the near future. Moreover, patients are now eligible for therapy as soon one is available. A nice example of PhD research with impact on healthcare.

Radboudumc
Promotion Janine Reurink – USH2A-associated disease. Genetics, pathogenesis and treatment
Thursday April 6, 2023 at 12.30 pm

Two groundbreaking projects awarded

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‘Moon Rocket Grant’ awarded to two groundbreaking projects

At this moment, there is no treatment yet for Usher Syndrome, a disorder that globally 400.000 people suffer from. In order to find a treatment that can stop, slow down or even reverse the process of becoming both deaf and blind, more knowledge and research into Usher Syndrome are needed.

Therefore Stichting Ushersyndroom (The Dutch Usher Syndrome Foundation) presents the ‘Moon Rocket Grant’: € 200.000, – for research into Usher Syndrome with a maximum of € 100.000, – for each study.

The Moon Rocket Grant
Stichting Ushersyndroom has launched the Moon Rocket Grant: a large pot of money for pioneering research into (a treatment for) Usher Syndrome. The objective of the Moon Rocket Grant from the Stichting Ushersyndroom is to effectuate a moonshot formulated by us: ‘A treatment for Usher Syndrome in 2025!’ This moonshot includes all types and subtypes of Usher Syndrome.

The study proposals must fit in with one of the four core values of the ‘Moon Rocket Grant’: Treatment, Knowledge, Diagnostics and Impact.
Every study (fundamental, translational or clinical) must lead to a treatment option, more knowledge and understanding, better diagnostics and an increase of the impact for every type of Usher Syndrome.

The Medical Advisory Council extensively tested and assessed all submitted study proposals. After this first assessment there was a second round: an on-line presentation with a short interview, after which the final selection for the award was made.

The Moon Rocket Grant goes to …..

Stichting Ushersyndroom announces with pleasure that two projects are eligible for the Moon-Rocket Grant 2022.

Prof Mariya Moosajee (UCL Institute of Ophthalmology, London, UK), will receive € 100.000, – for the project:

Prof Mariya Moosajee

“Large Gene Augmentation with non-viral episomal vectors for Usher syndrome”

Use of non-viral plasmid vectors for Usher Syndrome
It is well-known that the AAV (adeno-viral virus) vector is used for gene therapy, but this vector has a limit to the size of the gene. Most Usher genes are way too large for being packed into an AAV vector. When applying gene therapy to the retina of patients using the AAV vector, sometimes thinning of the retina (also called atrophy) can develop. Therefore alternative ‘packaging’ vectors are to be found for future gene therapies for Usher Syndrome.

Prof Mariya Moosajee has in cooperation with Dr Richard Harbottle (DKFZ German Cancer Research Centre, Heidelberg) developed a DNA plasmid (USH2A-S/MAR-vector) which can hold the full-length USH2A-DNA.
The DNA plasmid has been tested in a zebrafish model as well as in patient cells taken from a skin biopsy.

Prof Mariya Moosajee will use the ‘Moon-Rocket Grant’ to test the system of DNA plasmid in an already existing rabbit model for USH2A.
If the application of this alternative gene replacement strategy turns out to be successful, this will have a great impact for all inherited retinal diseases. After this study, it may be possible to start a phase 1 clinical trial for patients and it also may offer solutions for other large Usher genes. Gene therapy making use of DNA plasmid may have additional advantages; application (several times) with a limited immune response. Prof Mariya Moosajee hopes this approach will be safer and can avoid some of the complications that are seen in the current viral gene therapy. This project will at least take 2 years and has been budgeted at over € 200.000. Moorfields Eye Charity and Cure Usher will also be contributing to this project. With the contribution of the ‘Moon Rocket Grant’ from the Stichting Ushersyndroom the budget has been covered and the study can start.

The second project to be financed by the Moon Rocket Grant is the study of Monte Westerfield (Neuroscience, university of Oregon) and Erwin van Wijk (Radboud University Medical Center, Nijmegen, the Netherlands) entitled:

Prof. Monte Westerfield and Dr. Jennifer Phillips

“Exon-skipping as a future treatment for USH1F associated retinal disease” 

In this collaborative study Monte Westerfield of the University of Oregon and Erwin van Wijk of the Radboud UMC will develop and evaluate a treatment for Usher syndrome type 1F-related retinal disease based on the exon skipping methodology.

About 20.000 people worldwide lose their eyesight as a consequence of PCDH15 mutations. This condition is named USH1F.
The PCDH15 gene codes for the protocadherin 15 protein (PCDH15 protein) and is essential for normal eyesight and hearing. The PCDH15 protein contains multiple predicted extracellular cadherin (EC) domains. Many USH1F patients have mutations in the region encoding the EC domains number 6 (EC6) and 7 (EC7), resulting in a non-functional or even absent PCDH15 protein.

The ultimate goal of the researchers is to develop a treatment that halts the progression of PCDH15-associated visual dysfunction. For this, they will adopt the principle of “exon skipping” and develop a “genetic patch” that will instruct the light-sensitive cells inside the eye to skip the region of the PCDH15 gene that codes for the EC6 and EC7 domains. In this way a somewhat shorter but hopefully still functional PCDH15 protein is produced, specifically lacking the EC6 and EC7 domains.

A pilot study exploring the therapeutic potential of “exon skipping” for USH1F was conducted some years ago. In this study the researchers targeted another domain in the protein, but this did not result in a restored function of the PCDH15 protein. With the knowledge gained in the past few years the researchers can now better predict whether or not the remaining protein after exon skipping will be functional. Based on these improved prediction tools they now opt for “skipping” the region encoding EC domains 6 and 7.
In previous studies of both Monte Westerfield and Erwin van Wijk it was shown that zebrafish are suitable animal models for this study. To obtain functional proof for the proposed concept of skipping the EC6-EC7 encoding region of PCDH15, the researchers aim to remove this part of the PCDH15 gene from the zebrafish genome and analyze whether these ‘treated’ zebrafish will have a better eyesight than the untreated mutant zebrafish with USH1F mutations.

This research project was budgeted at € 100.000, – for a period of 24 months.

The objective of Stichting Ushersyndroom is to finance scientific research that is to lead to a treatment that will show down, stop of even reverse the deterioration of hearing and eyesight. Apart from this, the foundation also (financially) supports the improvement of the quality of life, the growth of knowledge and information about Usher Syndrome and to enhance the contact between fellow-sufferers.

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You can also donate directly to Stichting Ushersyndroom by using the QR code.

 

 

 

Study into the best approach of USH1B

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Stichting Ushersyndroom (Dutch Usher Syndrome Foundation) announces with pride its financing of a study that will test the best approach for USH1B (gene) therapy by making use of, among others, patient-specific cell models and a large animal model. This may take a (gene) therapy for USH1B to the pre-clinical phase. Dr. Kerstin Nagel-Wolfrum, who works at the Johannes Gutenberg University in Mainz, will lead this project.

Children suffering from Usher Syndrome type 1 (USH1) are born deaf and with a non-functioning organ of balance (the vestibular system). The first signs of loss of eyesight, such as night-blindness and a decreasing field of vision, will present themselves later in the childhood period. USH1 is most often caused by mutations in the MYO7A gene (USH1B). About 14% of all people suffering from Usher Syndrome has type 1B. The MYO7A gene is a very large gene and the Myosin protein is also called a motor protein. Is has a ‘head and a tail’ and therefore it must be replaced or processed as a whole when developing a gene therapy.

New approaches
The large size of the MYO7A gene makes classical gene therapy using an AAV vector impossible. However, new approaches, including double and triple AAV vectors, mini-genes, prime editing, translational read-through and exon skipping, are promising new alternative therapeutic strategies. Please go to the Knowledge portal for further reading.

From skin biopsy to mini-retina
With the help of a skin biopsy from a USH1B patient (fibroblast), Dr Nagel-Wolfrum can further develop these molecular cells into a retinal pigment ephithelium (RPE) and a retinal organoid (RO). The retinal pigment epithelium is found between the retina and the choroid and it clears away the waste products of the rods and cones in the retina. The retinal organoids are also called the mini-retinas.

The possibility to model retinal disorders by means of fibroblasts into mini-retinas created unprecedented opportunities in the research area.

Dr. Kerstin-Nagel-Wolfrum

Gain insights and test therapies
By making use of the ‘mini-retinas’, Dr Kerstin Nagel-Wolfrum will gain more insight into the mechanism that damages the retina and causes loss of eyesight. Apart from this, she wants to subject these retinal organoids (mini-retinas) to various therapies in order to test them for their effectiveness and functionality. Dr Nagel-Wolfrum will also test the mini-genes by conducting an AAV vector-based gene therapy.

On to the pre-clinical phase
A large animal model, a USH1B pig, has already been developed and is ready for testing possible therapies. Dr Nagel-Wolfrum will apply the therapy that the pre-study with the retinal organoids (mini-retinas) has shown to be the most effective one when doing research on the pig model. This study is called the pre-clinical phase. If this pre-clinical phase leads to positive results, this can be promising for a possible therapy for patients.

In this project Dr Kerstin Nagel-Wolfrum closely cooperates with:

  • U. Wolfrum (Institute for Molecular Physiology, JGU Mainz, Germany): USH1B pig model
  • S. Gerber (University Medical Centre Mainz, Institute of Human Genetics, Germany): Bioinformatics
  • M. Cheetham (UCL, London, United Kingdom): iPSC-RPE and iPSC-RO generation
  • V. Kalatzis (Institute for Neurosciences of Montpellier, France): iPSC-RPE and iPSC-RO generation
  • J. Gopalakrishnan (Heinrich-Heine University Düsseldorf, Germany): brain organoids

This project will have a duration of 1 year and has been budgeted at
€ 100.000, -. Stichting Ushersyndroom hopes that this study will contribute to the development of one or more effective treatments for people suffering from Usher Syndrome type 1B.

View the PowerPoint presentation about this research by Dr. Kerstin Nagel-Wolfrum

Tears as a source of information?

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Stichting Ushersyndroom and Usher Syndrome Ireland

finance research into USH1b

Can tears provide information that may be important for improving diagnostics and monitoring in future treatments of USH1b patients? In the pilot study “Investigating the exosome content as a novel marker for Usher syndrome 1b” Dr. Irene Vázquez Domínguez, who is working at the Radboudumc (Nijmegen, the Netherlands), will investigate tears. By doing this, she wants to assess whether there is any indications on tears that can be employed as a source of information and therefore may contribute to not only increase the current knowledge of the disease but also to allow better prediction of the development of Usher Syndrome type 1b.

This study will be mainly financed by the Usher Syndrome Foundation and partially co-financed by Usher Syndrome Ireland. If this study produces any positive results, the study of tears may lead to new strategies in USH research.

Tears
Tears are human body fluids. Tears are rich of proteins, lipoproteins and exosomes. Exosomes are small bladders which contain a wide range of molecules inside like RNA molecules. Thanks to that, exosomes are important for the communication between cells. In addition, they can be isolated from tears, which allow the study of their content.
As tears can be collected in a non-invasive way (without entering the body) from patients, they allow for easy and patient-friendly isolation of exosomes.

New biomarker for research
Biomarkers are measurable indicators that may indicate that someone is ill, predict how serious the illness will be or show whether a treatment is effective or not.

By making use of tears, the researcher Dr. Irene Vázquez Domínguez wants to find out whether biomarkers can be found that may be used to improve the diagnostics and to better predict the development of Usher Syndrome type 1b. In the long term, point-of-care tests could be developed on the basis of these biomarkers. Point-of-care tests offer care professionals the possibility to start, monitor or adjust a future development.

The MYO7A geneWe know that more than 10 genes are involved in Usher Syndrome.
This new study is focused on one of these genes, being the MYO7A gene. This gene is responsible for the production of a specific protein: Myosin, which keeps the photoreceptors (the rods and cones) of the retina alive.

Some children having mutations in the MYO7A gene do not develop retinitis pigmentosa in their childhood and puberty beside their hereditary deafness. Here we speak of non-syndromic deafness 

How can this be explained and/or predicted? The answer to this question may lead to better diagnostics. Sometimes it is really difficult for the parents to cope with the uncertainty whether or not their child will develop retinitis pigmentosa (RP).

Increasing the present knowledge about the MYO7A gene is necessary for finding new biomarkers that can be used for making the diagnosis and for predicting the development. At the same time, this knowledge can also be used in monitoring after a treatment.

Isolation of exosomes
Usher Syndrome falls within the group of Retinal Dystrophy diseases (RDs). The deterioration of the eyesight is caused by the dying of retinal cells, such as the light-sensitive photoreceptors and/or the retinal pigment epithelium (RPE).
Within the retina RPE cells are responsible for the majority of the production of exosomes. Previous studies indicated that tears may be rich of RPE exosomes.

The goal of the study is to isolate exosomes from tears as well as from RPE cells. Then, the content of both will be studied. First, the control group will be compared with the material from USH1b patients. Then the information from tear derived exosomes and RPE derived exosomes will be also compared to assess if, as it was suggested before, they provide the same information. If this turns out to be successful, this study will show that exosomes can be used as a means to develop new strategies in USH research.
Finally, this study will also show whether tears can be a source for research. This would help to find an easy and patient-friendly way to isolate exosomes.

This one year study was budgeted at  € 75.000, -.
Stichting Ushersyndroom (Dutch Usher syndrome Foundation) will finance this study with co-financing from Usher Syndrome Ireland.

 

Watch the powerpoint presentation by
Dr. Irene Vázquez Domínguez 

Research “Development of exon excision therapy”

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This study aims at permanently removing specific exons, which include hereditary mutations when patients are concerned, from the DNA of the photoreceptors in the retina and/or the hair cells of the inner ear with the help of the CRISPR/Cas9 gene editing technique. The objective of this strategy is to stop the deterioration of eyesight (and hopefully in the longer term that of hearing as well) with larger groups of patients who have mutations in these exons of the USH2a gene with a one-off treatment.

Dr Erwin van Wijk and his colleague Dr Erik de Vrieze (both working at Radboudumc) will study the effect of a new strategy for treating Usher Syndrome. The research group of these scientists will cooperate with Vasiliki Kalatzis of the University of Montpellier in France and apply the CRISPR/Cas9 in this study.

Development of exon excision therapy
Exon excision is a new treatment strategy for modifying genes that code larger structural proteins consisting of chains of repetitive protein domains. These protein domains are the functional parts within a protein. The idea is that a protein can do without one or more of these domains without losing its function. This can be compared with a chain. A large number of separate links that individually look the same together forms a chain. When a few links are taken out, the chain will indeed become a bit shorter, but it will still be functional.
At least four of the known Usher Syndrome-related proteins, being usherin (USH2a), ADGRV1 (USH2c), cadherin23 (USH1d) and protocadherin15 (USH1f), consist of a chain of repetitive ‘links’, called protein domains. Using the molecular pair of scissors ‘CRISPR/Cas9’, the genetic regions in the USH2a gene that code for such a repetitive protein domain and which also include hereditary defects when patients are concerned will be permanently removed from the DNA of photoreceptors. This will shorten the USH2a protein by one or more ‘links’ and the study is meant to find out whether it will still be functional. Mutations in the genes related to USH2a, USH2c, USH1d and USH1f together account for the underlying cause in as many as 75% of all Usher Syndrome patients! This emphasises the potential of this therapeutic strategy.

Jorden Leuverman: “It is particularly great to know that the interview has also resulted in something much bigger than just my sponsor campaign”

Personal involvement
It was an article in the Tubantia, which caught the eye of Inge Wessels. In the newspaper there was an interview with Jorden Leuverman in which he told about living with Usher Syndrome. Inge Wessels: “I was deeply touched. Jorden was very hard of hearing already and he would also slowly lose his eyesight.” Jorden was diagnosed with Usher Syndrome, just like his grandfather was. As Jordan knows the impact of this, he started a sponsor campaign for the Usher Syndrome Foundation. Together with his running buddy he participated in the footrace in Zutphen, the Netherlands, and with this collected € 5000.- for the Usher Syndrome Foundation, hoping that there will timely be a treatment for Usher Syndrome.
Inge Wessels: “When I read the interview in the newspaper, I felt such a deep respect for this man. I know from experience what it means to be deaf in daily life. Much information can be received by looking at the mouths of people talking and other non-verbal communication. When Usher Syndrome takes away your eyesight as well, I think this is really terrible.”

Can I help?
Inge Wessels supported the sponsor campaign of Jorden and also made a donation to Stichting Ushersyndroom. “Can I help you with the funding of a promising study?” Inge Wessels asked early this year.
Jorden: “I hoped to collect as much money as possible for Stichting Ushersyndroom with my sponsor campaign. This amount suddenly became a lot higher thanks to the fact that I was interviewed by a reporter of the Tubantia newspaper. It is particularly great to know that the interview has also resulted in something much bigger than just my sponsor campaign.”

Stop the process of becoming deaf and blind
About 400.000 people globally suffer from Usher Syndrome, of which about 1.000 in the Netherlands. Faults in about ten different genes lead to Usher Syndrome. These genes code for proteins that are crucial for the functioning of the eyes and the ears. At this moment, there still is no treatment for any type of Usher Syndrome that can slow down, stop or recover the process of becoming both deaf and blind.

Reggeborgh supports research the 4-year study ‘Development of the exon excision therapy’. We are really grateful to the Reggeborgh for its donation for this promising study!

f.l.t.r. Shannon Leuverman, Erik de Vrieze, Ivonne Bressers, Jorden Leuverman, Erwin van Wijk

New type of Usher Syndrome discovered: USH IV   

LEES ARTIKEL IN HET NEDERLANDS

The team of the Hearing & Genes Expert Centre of Radboudumc lately made a discovery: Usher Syndrome includes four different clinical types. The researchers, with Hedwig Velde as principal author, recently published their study and findings in the leading Human Genetics. With the identification of minor faults (mutations) in the ARSG gene and the description of a new clinical picture, they confirm the discovery of a fourth type of Usher Syndrome.  

This really is an important discovery, which gives more clarity about a number of patients with atypical Usher complaints without a genetic diagnosis. In the meantime, following the identification of ARSG as Usher gene, globally fifteen people have still been diagnosed, now that they all appear to have mutations in the ARSG gene. As it has been demonstrated that these patients have a common pattern of symptoms, this is no longer an atypical picture, but it makes up a new clinical type.       

A patient with an atypical clinical picture  
Very rarely a patients visits the outpatients’ clinic showing symptoms that correspond with the clinical picture of Usher Syndrome (loss of hearing combined with retinitis pigmentosa), but which picture deviates from the familiar Usher types. This is called an atypical clinical picture. In some cases no generic cause is found in the Usher genes that are known so far. Consequentially, these patients are unfortunately sent home again without having been diagnosed (and without any clarity). 

Hedwig velde

 Hedwig Velde is researcher and doctoral candidate at the ENT section Hearing & Genes of the Radboudumc. She is studying patients who suffer from loss of hearing but who have not been genetically diagnosed. With her research team she confirmed a new Usher Syndrome type, which is caused by minor faults in the ARSG gene.  

A publication from the year 2018 written by a group of scientists in Israel described the discovery of the ARSG gene with Arylsulfatase G as a protein that might be involved with Usher Syndrome. The researchers from Israel described five persons from three families who all had the same minor fault in the ARSG gene. Such a publication may give other researchers ideas for their studies.  

Studying the DNA of several people within one family sharing the same symptoms is a big help for scientists. Hedwig Velde: “There is a big chance that all patients within the family share the same genetic cause. When outside the family that has been studied another patient is found with the same atypical clinical picture and a minor fault in the same gene, this may confirm the relation between the gene and the clinical picture. Of course, the chance of coming across this patient is really small. Usher Syndrome is very rare.”  

Until the national Expert Centre in the Radboud UMC saw a patient with this atypical clinical picture of Usher Syndrome and Hedwig Velde and other researchers in the Radboud UMC continued the study that was started by the team in Israel in 2018.    

New type now confirmed  
With the publication of Hedwig Velde c.s. the researchers confirmed this new type. The researchers found minor faults in the same gene (the ARSG gene), which creates the codes for the Arylsulfatase G protein. This protein is involved in the degradation of another protein and the idea is that malfunctioning of Arylsulfatase G will lead to an adverse accumulation of the protein that normally should be destroyed. With this study the research team also demonstrated that the minor faults in the ARSG gene that have been found really result in a non-functioning protein.  

The clinical picture of the type does not fit in with the already known Usher types I, II and III. Apart from a later starting age of both the loss of hearing and the retinitis pigmentosa, the ophthalmic defects are more centrally located. This means that the vision problems with these patients rather occur in the central part of the field of vision as opposed to the other Usher types, which usually show problems in the outer part of the field of vision (the periphery). As the clinical picture is consistent with all USH IV patients, researchers of the Radboud UMC are of the opinion that this is not atypical Usher, but a new clinical type: Usher Syndrome type 4.   

Hedwig: “By publishing these findings, we as researchers hope to start up a discussion in the scientific world. Various studies may together lead to the confirmation that the findings are correct or, in some cases, rebut these findings. In case of USH IV it is the accumulation of evidence in several publications that enables us to confirm that this clinical type really is a new Usher type.”    

By now, globally several patients have been diagnosed for this Usher Syndrome type and for minor faults in the same ARSG gene. Previously, these patients used to be categorised in the group ‘diagnosis unknown with atypical Usher symptoms’.    

The course of Usher Syndrome type IV  
Both the loss of hearing and the complaints related to retinitis pigmentosa start at a later age with people suffering from USH IV. Patients started to develop complaints concerning hardness of hearing between the ages of 20 and 40 and the retinitis pigmentosa between the ages of 40 and 60. Based on the audiograms of USH IV patients, the research team has been able to calculate that the loss of hearing starts about the age of 17.  

The course and the progressiveness are not necessarily milder than with the other Usher types. “We still have little insight into the course of USH IV, because only fifteen patients have been described and we therefore have to base our findings on this small group.” 

Genetic tests or not?  
With this discovery the researchers of the Radboudumc have managed to fit in yet another piece of the ‘Usher puzzle’.” Thanks to this, a part of the patients with an unknown diagnosis will eventually be given clarity and this is really important to this group of patients.  

Unfortunately, there still are people for whom the Usher-related symptoms cannot be confirmed by a diagnosis. This makes genetic tests so important!    

The physicians indicate that, of course, the choice is still to be made by the patient. One patient attaches a lot of value to a confirmation by means of genetic tests, while another does not.  
Hedwig: “There are various reasons to have genetic tests done or not. An advantage of a genetic diagnosis is that with this the development of a disorder can better be predicted and that this may help the patient to adapt to the situation. Imagine that you are hard of hearing at a young age and that there is a small chance of becoming visually impaired. However, if you know that you will be visually impaired, then you had better concentrate on the kind of care that will help you both early and later in life. For instance, in this case learning sign language will not be a long-term solution for your loss of hearing, but good hearing aids may make a substantial contribution.”  

Genetic tests will also help the scientific world to get further. For example, as scientific research allows for comparing the DNA of various patients, new genetic causes can be discovered. Besides, this offers a possibility for meticulously mapping out the relation between a minor fault in a gene and the corresponding complaints.
Hedwig: “Because of this, future patients can be better informed about their diagnoses. On the other hand, it is also important for any future genetic treatments to know the exact underlying deviations in the DNA.”    

Usher Syndrome: 4 types and 11 genes involved
In 2022, type IV and the ARSG gene will be added to the list of Usher types and genes involved in the development of Usher Syndrome. So at this moment, Usher Syndrome distinguishes 4 types with 11 different genes involved. [Ed.: This evidence is not entirely conclusive for USH1J (CIB2) yet]
For all these genes scientific evidence has been provided that minor faults (mutations) in these genes will result in Usher Syndrome.    

The Knowledge Portal of the Usher Syndrome Foundation provides a complete overview of the genes with the names of the ‘protein involved’.     

Here you can read the publication of the article by Hedwig Velde c.s. in Human Genetics.  

 

New research: testing gene therapy

With extra large vectors on mini retinas 

Prof. Dr. Jan Wijnholds and promovendus Rossella Valenzano

Stichting Ushersyndroom [ Dutch Usher Syndrome Foundation] is funding the majority of the new research “Genetic drugs preventing blindness due to loss of USH2A function” which has recently started. The research team led by Jan Wijnholds, who works at the Leiden University Medical Center (LUMC), will test two treatment methods on ‘mini-retinas’ made from human stem cells. The researchers want to determine if the light sensitive cells in the mini-retinas can be activated by the light-sensitive cells after administration of gene therapy. Can the USH2a gene in the retina be replaced or is it also possible to repair the defective gene at the same time?

 

Gene therapy looks very promising and developments in this area are moving very quickly. It is a treatment method for hereditary disorders where healthy copies of genes, with errors (= mutations) have been found, in patients are replaced or repaired in the cells of an organ.

Research shows that after gene therapy, the retina can make normal connections with other cells, which can lead to a light response again. After delivering a healthy copy of the gene or repairing the gene, the retina makes the proteins it needs to see properly. With gene therapy you treat the entire gene so that it does not matter what kind of mutations you have.

Means of transport for the large USH2A gene
In gene therapy, a healthy copy of the gene is delivered to a specific location in the retina of the eye using a molecular truck, or a means of transport. This is usually done using a virus that has first been rendered harmless so that a vector remains, a kind of ‘packaging’. The most commonly used vector is the adeno-associated viral vector (AAV).
However, there is a problem. The USH2A gene is much too large for a normal AAV vector, so another alternative must be sought to deliver the large healthy copy of the USH2A gene into a patient’s eye.

Large trucks as vector
Previously, in collaboration with Dr Manuel A.F.V Gonçalves (Department of Chemical Cell Biology), the researchers in Jan Wijnholds’ lab at the LUMC, have developed new vectors into which very large genes fit, the so-called High-Capacity Adenoviral Vectors (HcAdV).
The large USH2A gene fits completely into this vector. As a result, this vector can serve as a molecular truck and can be used as a vector for gene therapy.

Mini retinas
In the research project “Genetic drugs preventing blindness due to USH2A function”, human mutant USH2A iPSC retinal organoids are used to test several new high-DNA capacity gene therapy vectors. These USH2A ‘organoids’ are ‘mini-retinas’ made from cell lines derived from USH2A patients.

These ‘mini-retinas’ are used because they allow to study the effect of loss of USH2A protein (Usherin) in the cilium of the photoreceptor. The cilium transports the essential proteins in the retina. These ‘organoids’, made from patient cell lines, could also be used in the future to test gene therapy for retinal disorders due to mutations in other Usher genes.

Replace gene and/or edit gene
In the research project of Jan Wijnholds, two types of gene therapy are being tested on the ‘mini retinas’. The first type of therapy candidate is an HcAdV vector containing a healthy copy of the USH2A gene that, after delivery, replaces the defective USH2A gene in the retina. We call this gene replacement therapy. The healthy copy of the gene must activate the gene in the photoreceptors of the ‘mini retinas’, the ‘organoids’.

The second type of therapy candidate is an HcAdV vector containing ‘a repair kit’ and, after delivery into the retina, repairs the defective USH2A gene in the eye itself. This is also known as gene editing therapy, CRISPR-Cas9 is used for this. CRISPR are pieces of DNA with codes that can detect the defective gene. The Cas9 is an enzyme that ‘cuts’ out the defective gene and ‘sticks’ a new healthy piece of DNA in it.

Both the CRISPR and Cas9 are transported in a cassette and delivered into the retina by an HcAdV vector. The USH2A gene is edited and repaired at its destination.

Promises for large groups of patients
Both technologies for genetherapeutic application are not dependent on the type of mutations in the USH2A gene. If the USH2A gene is found to be expressed in the light-sensitive cells of the mini-retinas thanks to one or both techniques, the treatment may become available to all patients with USH2A. When more money becomes available for research for these two techniques , the research team of Jan Wijnholds could also test these for other Usher genes, and could possibly also be a solution for patients with mutations in Usher genes other than USH2A.

The mission of Stichting Ushersyndroom
Annouk van Nunen, secretary of Stichting Ushersyndroom, is very pleased with the start of this research. Stichting Ushersyndroom’s mission is “In 2025, Usher Syndrome will be treatable!”.Annouk: “We want all patients to have a realistic prospect in 2025 of a treatment that can slow down, stop or even restore the further deterioration of their hearing and vision”.

The big challenge for scientists is to explore multiple research routes in order to eventually develop a treatment for all people with Usher syndrome. Stichting Ushersyndroom therefore stimulates as many lines of research as possible, so that people with Usher Syndrome can make their dreams come true. “It is fantastic that so much research is being done into Usher Syndrome in the Netherlands. This type of research is hopeful for all USH2A patients. But if it works, it could also be a solution for patients with mutations in other Usher genes, Annouk van Nunen.

This four-year study, which started in November, has been budgeted at € 250.000. Stichting Ushersyndroom is contributing € 85.000 to this research. Other funds that have contributed are: Rotterdamse Stichting Blindenbelangen, LSBS, Stichting Blindenhulp and a partial contribution from the LUMC Ophthalmology Departmen