Norrie disease is an X-linked recessive syndrome of blindness, deafness, and mental retardation.
Affected males are blind at birth or early infancy. About 25% are mentally retarded and about one-third develop progressive sensorineural hearing loss, with onset at any time from infancy to adult life, which may lead to profound deafness. The ocular findings include abnormal vascularization of the peripheral retina, bilateral retinal folds, traction retinal de tachment, vitreous haemorrhage and bilateral retrolental masses. The retinal detachments are usually of early onset and have been diagnosed in utero. Most cases progress to an extensive vitreoretinal mass and bilateral blindness. The gene for Norrie disease has been identified on Xpii.4. Norrin,the product of the Norrie disease gene, is a secreted protein important for normal retinal vascularization and regression of hyaloid vessels and also regulates the interaction of the cochlea with its vasculature.
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