Symptoms
Symptoms of Norrie disease may include:
Blindness in both eyes at birth or soon after Leukoria, in which pupils appear white when light is shined on them The colored parts of the eyes (irises) shrinking after birth Eyeballs that shrink after birth Cloudiness in the lenses of the eyes (cataracts)
About one-third of people with Norrie disease develop progressive hearing loss, and more than half experience developmental delays in motor skills such as sitting up and walking. Other problems may include mild to moderate intellectual disability, behavioral disorders, and physical abnormalities that can affect circulation, breathing, digestion, excretion, and reproduction.
Causes
Mutations in the NDP gene on the X chromosome cause Norrie disease. It is inherited in an X-linked recessive pattern.
The NDP gene is responsible for making a protein called norrin. The genetic mutation interferes with norrin’s role in what’s called the Wnt cascade, a sequence of steps that affect the way cells and tissues develop. In particular, norrin seems to play a critical role in the specialization of retinal cells for their unique sensory capabilities. It is also involved in the establishment of the blood supply to tissues of the retina and the inner ear, and the development of other body systems.
Diagnosis
To diagnose Norrie disease, a doctor will first look at your child’s medical history, symptoms, and any laboratory test results. If the child’s symptoms suggest the condition, an ophthalmologist (eye doctor) will examine his eyes. If Norrie disease is present, the ophthalmologist will see an abnormal retina at the back of the eye.
The diagnosis can also be confirmed by genetic testing for mutation of the NDP gene on the X chromosome.
Treatment
Because Norrie is a systemic genetic disease, a team of doctors including ophthalmologists, audiologists, geneticists, neurologists, and others will be involved with the care of a Norrie-affected individual.
Although most infants have complete or severe retinal detachment at birth, those that do not have complete retinal detachment may benefit from surgery or laser therapy. Rarely, one or both eyes may need to be removed, a process known as enucleation. Audiologist evaluation with possible hearing aids or cochlear implants may be necessary for some.
Medical treatment may be needed for other problems the disease may cause, such as breathing or digestion. A child with Norrie disease may require special education services as well as therapy to address any behavioral problems.
A Word From Verywell
While there is no cure for Norrie disease, some symptoms can be managed effectively. The Genetic and Rare Diseases Information Center can help you find a specialist who is familiar with the disease.
