Norrie's Disease

By: Caleb Shaffer and Katie Warkentine

Norrie's Disease Description

Norrie disease is an inherited eye disorder that leads to blindness in male babies at birth or soon after birth. It causes abnormal development of the retina, the layer of sensory cells that detect light and color, with masses of immature retinal cells accumulating at the back of the eye. This causes the pupils appear white when you shine light on them. The irises or sometimes even the entire eyeballs may shrink and deteriorate during the first months of life, and cataracts may eventually develop. About one third of individuals with Norrie disease develop hearing loss, and more than half experience delays in motor skills such as sitting up and walking. Other problems may include mild to moderate intellectual disability, and defects in circulation, breathing, digestion, excretion, or reproduction.

Signaling Pathway and Mechanisms

The Wnt cascade affects the way cells and tissues develop. In a normal pathway norrin binds with frizzled-4 to specialized retinal cells and their unique sensory capabilities. With norrie's disease the NDP gene mutates the norrin protein which prevents the bonding of frizzled-4 which causes blindness.
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Current Direction of Research

The treatment of Norrie disease requires the coordinated efforts of a team of specialists. Pediatricians, specialists who assess and treat eye abnormalities, audiologists, and other healthcare professionals. The treatment of individuals with Norrie disease is more directed toward the specific symptoms that are apparent in each individual than the direct disorder. Surgery may be necessary to remove cataracts and reattach retinas. This may prevent shrinkage of the eyeballs, but will not improve vision. Hearing aids may be of benefit for those with hearing loss. Special attention to the mental delays associated with Norrie's Disease is necessary for the children that have it.

Researchers have discovered that genetic mutations underlying two inherited eye disorders arise in different components of a single intracellular signaling pathway that is responsible for development of blood vessels in the eye. Understanding more about how this pathway functions could provide useful information for the development of drugs to treat the disease.