Norrie Disease

X-linked recessive disorder caused by mutations in the NDP gene (Xp11.3), which encodes norrin, a secreted Wnt-pathway ligand for frizzled-4 essential for retinal and inner-ear vascular development.

Congenital bilateral blindness in affected males is the defining, earliest feature.

Progressive sensorineural hearing loss occurs in ~30%, usually later onset (childhood into adulthood).

Neurodevelopmental involvement in a substantial subset: developmental/motor delay (~30–50%), mild-to-moderate intellectual disability, behavioral problems/psychosis, autism features, and seizures. Larger deletions (complete norrin loss) → more severe multisystem disease.

Retrolental mass (“pseudoglioma”) — grayish-yellow mass of immature retinal cells resembling retinoblastoma, present at or shortly after birth.

Leukocoria — hallmark sign; with retinal dysplasia and partial/complete retinal detachment.

Progressive anterior/globe changes — cataract, corneal opacification, iris atrophy, synechiae, secondary glaucoma/buphthalmos, and eventual phthisis bulbi, typically within the first decade.

Microphthalmia and nystagmus are common.

Auditory: progressive sensorineural hearing loss in ~30%, requiring surveillance and eventual hearing aids/cochlear implantation.*[1][2][5][6]

Neurodevelopmental/psychiatric: developmental delay, intellectual disability, psychosis/behavioral problems, autism features, seizures.*[1][2][4]

Allelic conditions (NDP-related retinopathies): familial exudative vitreoretinopathy (FEVR), [Coats disease](https://www.openevidence.com/rare-disease/coats-disease), persistent fetal vasculature (PHPV), and retinopathy of prematurity.

Gene/inheritance: pathogenic variants in NDP, inherited X-linked recessive; affected males hemizygous, carrier females typically unaffected. >115 mutations reported (missense, splice, intragenic/large deletions), with genotype–phenotype correlation (deletions → severe).

Mechanism: loss of norrin disrupts Wnt/frizzled-4 signaling required for retinal and cochlear vascular development and retinal cell specification.

Differential/phenocopies: truncating CTNNB1 mutations can cause a Norrie-like phenotype, with overlap with KIF11; ~30% of clinically diagnosed families have no identifiable NDP variant.

Genetic testing: Sanger sequencing for point mutations/small indels; deletion/duplication analysis (MLPA/dosage) for large deletions; NGS/whole-exome sequencing for ambiguous cases or to capture CTNNB1/KIF11. Once the familial variant is known, carrier, prenatal (amniocentesis/CVS), and preimplantation testing are available; third-trimester ultrasound may suggest the diagnosis. * Treatment (supportive, multidisciplinary; no approved disease-modifying therapy): * **Ocular — individualized pediatric vitreoretinal care; most infants have complete detachment at birth limiting surgery to preserving light perception/globe. In eyes without complete detachment, prophylactic laser photocoagulation at/shortly after birth has preserved useful vision. Vitrectomy (± lensectomy) in selected infants; manage secondary glaucoma; enucleation occasionally for a painful blind eye. * Auditory — audiologic monitoring, hearing aids, cochlear implantation. * Neurodevelopmental — developmental, behavioral, educational support; seizure and psychiatric management. * Emerging — systemic **AAV9-mediated //NDP gene therapy** rescued retinal and cochlear pathology in a Norrie mouse model (preclinical).

MedlinePlus: Norrie disease

GeneReviews: NDP-Related Retinopathies (Scruggs, Reding, Schimmenti)

MedlinePlus: NDP gene

Pauzuolyte et al. Systemic Gene Therapy Rescues Retinal Dysfunction and Hearing Loss in a Model of Norrie Disease, EMBO Mol Med 2023

Chow et al. Laser Photocoagulation at Birth Prevents Blindness in Norrie's Disease, Ophthalmology 2010