Norrie disease

X-linked recessive

Norrie disease is a rare genetic disorder that primarily affects the eyes and leads to blindness in male infants at birth or shortly thereafter. The condition is named after the Scottish ophthalmologist Gordon Norrie, who first described it in 1927.

Genetics

Norrie disease is caused by mutations in the NDP gene located on the X chromosome. This gene is responsible for producing a protein called norrin, which is crucial for the development of the retina and the inner ear. Because the gene is located on the X chromosome, Norrie disease follows an X-linked recessive inheritance pattern. This means that males, who have only one X chromosome, are more severely affected, while females, who have two X chromosomes, are typically carriers and usually do not exhibit symptoms.

Symptoms

The primary symptom of Norrie disease is congenital blindness, which is present at birth. Other ocular symptoms may include retinal detachment, cataracts, and microphthalmia. As the disease progresses, affected individuals may develop hearing loss and, in some cases, intellectual disability. Additional symptoms can include developmental delay, behavioral problems, and seizures.

Diagnosis

Diagnosis of Norrie disease is based on clinical evaluation, family history, and genetic testing. Ophthalmologic examination can reveal characteristic changes in the retina, while audiometric testing can assess hearing loss. Genetic testing can confirm the diagnosis by identifying mutations in the NDP gene.

Treatment

There is currently no cure for Norrie disease. Treatment focuses on managing symptoms and may include surgical intervention for retinal detachment, hearing aids for hearing loss, and special education services for developmental delays. Early intervention and supportive therapies can improve the quality of life for affected individuals.

Related Pages

• Genetic disorder
• X-linked recessive inheritance
• Retinal detachment
• Hearing loss
• Intellectual disability

See Also

• Gordon Norrie
• NDP gene
• Congenital blindness