Norrie Disease (ND)

Norrie disease (ND), a multifactorial genetic condition, affects vision and hearing. At Protheragen, our team of experts has extensive experience in developing comprehensive diagnostics and therapeutic solutions for Norrie disease.

Overview of Norrie Disease (ND)

Norrie disease (ND) is classified as an uncommon X-linked recessive condition that presents itself with bilateral blindness at birth and continuous sensorineural hearing loss. The disorder results from genetic mutations in the Norrie disease pseudoglioma (NDP) gene which is responsible for producing a protein known as norrin. This protein is highly significant in developing the retinal blood vessels along with the inner blood-retinal barrier. Disruptions in the NDP gene lead to abnormalities in the vascular development of the retina, which causes hypoxia and tractional retinal detachment. This complication is the reason behind being blind at birth. Furthermore, cases are most of the time bound to experience progressive hearing loss and at times cognitive dysfunction, alongside other psychiatric symptoms.

Fig.1 Case studies of systemic delivery of AAV9. NDP therapeutics. (Pauzuolyte V., et al., 2023)

Diagnostics Development for Norrie Disease

Genetic Testing

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The best option for Norrie Disease diagnostic evaluation is genetic testing, which consists of identification of mutations in the NDP gene by means of targeted Sanger sequencing or whole-exome sequencing. Amplification methods for microdeletions and microduplications such as MLPA as well as chromosomal microarray may also reveal deletions or duplications in the NDP and surrounding regions.

Biochemical Analysis

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The biochemical analysis of cerebrospinal fluid (CSF) can detect changes that correlate with Norrie Disease. Biogenic amines and serotonin and some of their metabolites are measured by high-performance liquid chromatography (HPLC). One case study involving a patient with Norrie Disease has revealed that individuals may have almost no imaginative concentrations of these metabolites, which implies a profound insufficiency of monoamine oxidase (MAO) activity.

Therapeutics Development for Norrie Disease

The ability of gene therapy to resolve Norrie Disease by functional NDP cDNA transfer to affected tissues appears to be hopeful. The human NDP gene has been packaged in adeno-associated viral (AAV) vectors like AAV9, which has been administered to a mouse model of Norrie Disease. Moreover, AAV9 NDP gene intravenous administration has proved efficacious in rescuing retinal dysfunction and hearing impairment, paving the way for future therapeutic utilization.

The pathophysiological basis of Norrie Disease is of great importance currently and attempts are being made in many human trials using non-single gene therapies as well as small molecules to treat it. These trials have the aim of finding the best therapeutic agents to halt or decelerate the disease and improve the prognosis.

Our Services

At Protheragen, we offer comprehensive services for the development of diagnostics and therapeutics for Norrie Disease. Our services include:

ND Target Validation & Molecular Mechanism Characterization

Protheragen supports target validation by defining how candidates restore norrin‑Wnt signaling and reverse pathological cascades. Services include:

• NDP variant functional annotation: in vitro testing of patient‑derived missense, nonsense, and frameshift variants to quantify residual norrin activity, FZD4 binding, and β‑catenin signaling competence
• Wnt pathway reactivation assays: TOPFlash/FOPFlash luciferase reporter systems to measure small‑molecule or biologic‑mediated pathway recovery
• Protein–protein interaction (PPI) analysis: FZD4/LRP5 binding affinity, norrin multimerization, and extracellular matrix interactions using SPR and co‑IP
• Transcriptomic and proteomic profiling: RNA‑seq and LC‑MS/MS to map global expression changes in normal vs. ND‑deficient retinal cells, identifying dysregulated genes and druggable nodes
• Neuroprotective and anti‑fibrotic mechanism profiling: assessment of candidate effects on retinal cell apoptosis, Müller glia activation, and extracellular matrix deposition

These data establish MoA, prioritize lead candidates, and support intellectual property positioning for ND therapies.

Custom In Vitro ND Model Development & Screening

We provide physiologically relevant human and mammalian in vitro systems for high‑throughput screening and mechanistic studies:

• Primary retinal cell cultures: rodent and human fetal retinal cells, endothelial cells, pericytes, and Müller glia under NDP‑knockdown or mutant conditions
• 3D retinal organoids: human pluripotent stem cell (hPSC)‑derived retinal organoids carrying engineered NDP mutations, recapitulating vascular dysplasia, lamination defects, and neuronal degeneration
• Immortalized ND cell lines: stable NDP‑null and mutant reporter lines for rapid compound screening and dose–response testing
• Inner ear cochlear explant cultures: for assessing auditory neuroprotection and vascular rescue, a key extraocular component of ND
• High‑content imaging (HCI): automated quantification of vascular network formation, neurite outgrowth, cell survival, and β‑catenin nuclear translocation

These models enable cost‑effective lead optimization before in vivo testing, with data directly relevant to human ND pathology.

Ex Vivo Ocular Functional Assays for ND Therapeutics

We offer ex vivo ocular testing to bridge in vitro and in vivo phases with tissue‑level physiological relevance:

• Ex vivo retinal electrophysiology: ERG measurements on isolated retinas to quantify rescue of a‑wave, b‑wave, and oscillatory potentials
• Retinal vascular explant assays: assessment of endothelial tube formation, sprouting, and perfusion in ND‑model retinal tissues
• Ocular tissue distribution and penetration: quantification of candidate delivery to retina, vitreous, and retinal pigment epithelium (RPE) using fluorescent labeling and LC‑MS/MS
• Extravascular retinal cell survival: TUNEL, caspase activity, and immunohistochemical mapping of photoreceptor and ganglion cell viability

These assays refine formulation, dosing, and delivery routes before in vivo studies.

In Vivo ND Model Characterization & Efficacy Testing

Protheragen provides comprehensive in vivo testing using genetically validated ND animal models, with rigorous functional and structural endpoints:

• ND mouse model characterization: Ndp knockout and knock‑in lines with longitudinal assessment of retinal vasculature, lamination, and function
• Retinal vascular imaging: fundoscopy, FA, and OCT to quantify peripheral perfusion, capillary layer formation, and proliferation
• Retinal electrophysiology: full‑field ERG (ffERG) and pattern ERG (PERG) to measure visual function rescue
• Auditory phenotyping: ABR to assess cochlear function and hearing preservation
• Histopathology and IHC: retinal layer thickness, cell counts, norrin expression, and fibrosis markers
• Molecular endpoint quantification: qPCR and Western blotting for Wnt pathway genes and inflammatory mediators

Studies include dose–response, route comparison (intravitreal, subretinal, systemic), and long‑term durability up to six months.

In Vitro Safety Pharmacology & Ocular Tolerability Assessment

We deliver non‑clinical safety profiling to de‑risk candidates and support regulatory filings:

• In vitro cytotoxicity and cell viability: retinal cells, RPE, and cochlear cells to establish therapeutic windows
• Ocular irritancy and tolerability: ex vivo bovine and rabbit corneal endpoints for local safety
• Off‑target signaling profiling: broad kinase and pathway screening to avoid unintended Wnt modulation
• Oxidative stress and inflammatory response: quantification of ROS, nitric oxide, and pro‑inflammatory cytokines
• Biodistribution and nucleic acid safety: for gene therapies, vector genome copy number and expression mapping

All safety data are structured for IND‑enabling toxicology study design.

ND Biomarker Development & Longitudinal Monitoring

We identify and validate translatable biomarkers to streamline clinical development:

• Aqueous humor and vitreous biomarker panels: angiogenic, inflammatory, and neuronal injury proteins
• Retinal imaging biomarkers: quantitative OCT and FA metrics for clinical trial readouts
• Circulating biomarkers: serum proteins and microRNAs for non‑invasive monitoring
• Electrophysiological biomarkers: ERG and ABR endpoints predictive of structural rescue

Biomarker validation is performed across in vitro, ex vivo, and in vivo systems to ensure clinical transferability.

Diagnostics Development

• Karyotype Analysis Service
• Omics Analysis Service
• Biomarker Development Service
• Artificial Intelligence Service
• Customized Diagnostics Development

Therapeutic Development

• Small Molecule Drug
• Cell Therapy
• Gene Therapy
• Therapeutic Antibody
• Therapeutic Peptide
• Therapeutic Protein
• Customized Therapy Development

Disease Models

Ndp^tm1Wbrg Mouse Models: abnormal retinal vascularization and progressive hearing loss

ND Gene Mutant Mouse Models: the murine homologue of the ND gene was cloned and shown to encode a polypeptide that shares 94% of the amino acid sequence with its human counterpart.

Protheragen works with clients to design therapeutic strategies that target the underlying genetic and biochemical abnormalities associated with Norrie Disease. If you are interested in our services, please feel free to contact us.

Reference

• Pauzuolyte, Valda, et al. "Systemic gene therapy rescues retinal dysfunction and hearing loss in a model of Norrie disease." EMBO Molecular Medicine 15.10 (2023): e17393.