Genetic Link ?

Here is some information about the possible genetic link to Coats' disease. In some circles, it is believed that Coats' disease is caused by a somatic mutation of the NDP gene. Mutations of this gene can also cause Norrie Disease. This page is just informational, we are not trying to suggest that Coats' disease will lead to Norrie Disease.

What is Norrie disease?

Norrie disease is an inherited eye disorder that leads to blindness in male infants 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. As a result, the pupils appear white when light is shone on them, a sign called leukocoria. The irises (colored portions of the eyes) or the entire eyeballs may shrink and deteriorate during the first months of life, and cataracts (cloudiness in the lens of the eye) may eventually develop.

About one third of individuals with Norrie disease develop progressive hearing loss, and more than half experience developmental delays in motor skills. Other problems may include mild to moderate mental retardation, often with psychosis, and abnormalities that can affect circulation, breathing, digestion, excretion, or reproduction.

 

What is the official name of the NDP gene?

The official name of this gene is “Norrie disease (pseudoglioma).”

NDP is the gene's official symbol.

What is the normal function of the NDP gene?

The NDP gene provides instructions for making a protein called norrin. This protein is believed to be crucial to normal development of the eye and other body systems. In particular, it seems to play critical roles in the specialization of the cells of the retina (the thin layer at the back of the eye that senses light and color) and the establishment of a blood supply to tissues of the retina and the inner ear.

What conditions are related to the NDP gene?

Norrie disease - caused by mutations in the NDP gene

Many different mutations of the NDP gene cause Norrie disease. These mutations interfere with the role of the norrin protein in the specialization of retinal cells for their unique sensory function. As a result, masses of immature retinal cells accumulate in the back of the eyes. Disruption of norrin's role in the establishment of blood vessels supplying the eye eventually causes some of the tissues to break down.

Norrin is also expressed in other systems of the body, and the effects of the disorder can be widespread. Specific abnormalities and their severity depend on the type and location of the NDP mutation. Mutations that delete portions of the NDP gene prevent production of norrin and result in severe problems affecting many body systems in addition to the eyes. Mutations that delete or change just a single protein building block (amino acid) usually result in less widespread effects.

Other retinal dystrophies - caused by mutations in the NDP gene.

NDP mutations may cause other disorders that affect the retina. One mutation is associated with a disorder called Coats' Disease that causes leakage of blood vessels in the retina and retinal detachment. Other NDP mutations may cause exudative vitreoretinopathy, another condition that results in progressive damage to the retina.

In addition, NDP mutations influence the course of a retinal disorder that affects some premature infants. Babies with retinopathy of prematurity may experience improvement of the condition over time, but in those with NDP mutations, the condition tends to worsen.

 

Also from PubMed:

 Coats' disease of the retina (unilateral retinal telangiectasis) caused by somatic mutation in the NDP gene: a role for norrin in retinal angiogenesis.

Black GC, Perveen R, Bonshek R, Cahill M, Clayton-Smith J, Lloyd IC, McLeod D. University Department of Medical Genetics and Regional Genetics Service, St Mary's Hospital, Manchester M13 OJH, UK.

 Coats' disease is characterized by abnormal retinal vascular development (so-called 'retinal telangiectasis') which results in massive intraretinal and subretinal lipid accumulation (exudative retinal detachment). The classical form of Coats' disease is almost invariably isolated, unilateral and seen in males. A female with a unilateral variant of Coats' disease gave birth to a son affected by Norrie disease. Both carried a missense mutation within the NDP gene on chromosome Xp11.2. Subsequently analysis of the retinas of nine enucleated eyes from males with Coats' disease demonstrated in one a somatic mutation in the NDP gene which was not present within non-retinal tissue. We suggest that Coats' telangiectasis is secondary to somatic mutation in the NDP gene which results in a deficiency of norrin (the protein product of the NDP gene) within the developing retina. This supports recent observations that the protein is critical for normal retinal vasculogenesis.

 PMID: 10484772 [PubMed - indexed for MEDLINE]

The information on this page should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional.