Gyrate Atrophy

What is Gyrate Atrophy?

Gyrate atrophy of the choroid and retina (GACR) is a rare autosomal recessive metabolic disease caused by a mutation in the gene encoding for ornithine δ-aminotransferase (OAT).

This mutation directly affects ornithine metabolism, resulting in hyperornithinaemia which ultimately induces progressive vision loss. Most patients present with myopia and nyctalopia in the first decades of life. This is followed by gradual peripheral visual loss and cataracts and sooner or later leads to complete blindness by the age of 50. It is currently unknown why hyperornithinaemia induces this decline in vision.

Besides vision loss a subset of patients suffers from muscle weakness, epilepsy and cognitive impairments; the complete phenotype, however, is not yet known. The incidence of GACR is currently also unknown, but it is a very rare and most certainly under-recognized disease.

What is our mission?

Our mission is to enable a healthy future for all GACR patients by preventing the irreversible damage resulting from hyperornithinaemia.

To achieve this mission, we have set the following goals:

Delineate the GACR geno- & phenotype, disease course, treatment strategies and clinical outcomes.
Generate GACR disease models, i.e. retina-in-a-dish research.
Understand the molecular mechanisms and biochemical pathways responsible for vision loss and other symptoms.
Establish evidence-based consensus guidelines for patient care & digital tools.
Develop, trial and disseminate novel treatment modalities.

Why is research needed?

Since GACR is such a rare disease with a scattered patient population, opportunities for research are slim, resulting in limited availability of literature. Full clinical/biochemical phenotype and pathogenesis thus remain unclear, treatment options remain limited and care is often uncoordinated with poor outcomes.

Only through collaboration with different research fields and nationalities we have a chance to improve the standard of living for patients suffering from GACR from an early age. We therefore have assembled a multidisciplinary team of clinicians and researchers from different countries with the aim to prevent the debilitating blindness caused by GACR and other symptoms.

Motivation

By reaching out to GACR professionals world-wide in 2019, it became clear that management protocols are not harmonized and current therapeutic modalities are insufficiently effective. This motivated us to set up an evidence-based approach for diagnosing and treating GACR patients.

We also spoke with several patients who suffer from this devastating illness who underlined the need for more research. As current treatment options are poor and not very effective, blindness is inevitable when diagnosed with GACR. Now we have assembled a strong team comprising various experts who, together with the patients and families, will synergize their strengths and energies to improve GACR care.

How do we want to accomplish our research goals?

We aim to accomplish our mission by executing the following plans:

GACR Patient Registry

Establish and populate an international GACR Patient Registry, together with our collaborators in the Netherlands and abroad. We will make an appeal to the laboratory and clinical colleagues in multidisciplinary settings to identify all GA patients, obtain data on demographics, family history, clinical course and biochemistry. We will also obtain data on treatment strategies, patient adherence and specific outcome measures. The data will be entered and regularly updated into the international GA patient registry.

Patient Care Guidelines

Develop and publish recommendations / guidelines for GACR patient care, diagnosis and management.
Based on current literature plus our own research data, we will host GACR multidisciplinary Delphi consensus meetings in order to publish recommendations and guidelines for GACR patient care.

GACR Biobank

Establish and maintain an international GACR biobank (location Amsterdam UMC) for the collection of patient samples (DNA, full blood, plasma, bloodspot, urine, and if available such as cerebrospinal fluid, fibroblasts, lymphoblasts) for further research.

Connecting GACR Community

Connect the GACR community through this website, provide information on GACR and translate research into better care and outcomes. Develop mobile health and social media tools to aid clinicians and patients in the treatment process.

Metabolomics

Perform untargeted metabolomics to identify potential biomarkers specific to OAT deficiency.
We will perform untargeted metabolomics on body fluids to delineate the biochemical profile and to identify biomarkers specific to OAT deficiency.

Small Compound Library Screening

Perform high-throughput small compound library screening with already existing and FDA approved drugs from the PRESTWICK chemical library to determine if it possible to induce/increase the residual OAT activity.

Novel treatment modalities

Develop, trial and disseminate novel treatment modalities: repurposing of drugs and enzyme & gene-based therapies.

Therapy Development
Our GACR research group uses induced pluripotent stem cells (iPSCs) derived from GACR patients which we compare to healthy controls. From the iPSCs we are able to generate retinal organoids and develop retinal pigment epithelium cells. These advanced models are more representative of the in vivo situation compared to standard culturing methods and thus allow us to gain a better understanding of the mechanisms that are affected in GACR patients. We will perform numerous experiments (western blot, RT-PCR, RNA-seq, MTT assay, immunohistochemistry staining, intracellular amino acid analysis) in order to completely characterize our GACR models. We aim to identify the underlying mechanism responsible for the damage caused by ornithine accumulation. Once we identify this toxic mechanism we will experiment with potential treatment options that are able to prevent this damage from occuring.

Timeline

Click to enlarge

We need you!

Team work is essential in research and care for rare diseases and our plans are ambitious. We kindly invite you as health professional, researcher and/or patient & family to join our efforts. Thanks to our sponsors, we have obtained enough funding to start our project. Of course we will need more funding to continue our research and reach our goals, i.e. a healthy future for all GACR patients. We and our patient community would be really thankful for any donations to support this great cause.

Contact us

If you would like more information about GACR and our research project, or if you are/know a GACR patient who would like to participate in our research project, feel free to contact us at the following email address: GAresearch@amsterdamumc.nl or use the form below.

In order to carry out this project we have received funding from the AMC Foundation, Stichting Steun Emma, Stichting Metakids, Amsterdam Gastroenterology and Metabolism research institute (AGM) and the horstingstuit foundation.