Fanilial Exudative Vitreoretinopathy, EVR3
Patient Information
Characteristics
Background and History
Vitreoretinopathy refers to a condition in the back of the eye in which a primary retinal vascular disease also impacts the vitreous, the jelly-like material that fills much of the eye. It is believed to begin at birth when the retinal vessels are interrupted in development causing the retina to be starved of oxygen. This sets into motion a chain of events that leads to the growth of new abnormal vessels which subsequently bleed causing scarring of the retina and vitreous that may ultimately cause a retinal detachment and blindness. EVR3 is only one of several disorders that result from this process.
Clinical Correlations
There is considerable variation in the eye findings. The abnormal blood vessel development in the retina may result in blindness among newborns but other patients can have only minor abnormalities into adulthood. Abnormal vessels often leak blood into the vitreous humor (the gel-like material that fills the back part of the eye) causing scarring that progresses to a pulling on the retina and eventually detaches it. This is a threat throughout life. A few individuals have cataracts.
No general abnormalities outside the eye have been reported.
Genetics
Inheritance
This condition likely results from mutations in a specific gene as yet unidentified. The family transmission pattern is consistent with an autosomal dominant inheritance mode in which affected parents can have affected offspring. In this case the risk of transmission is 50%. Only a single mutation is necessary.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
An ophthalmologist (eye doctor) can make the diagnosis at any age depending upon the stage of disease. Longevity is not impacted but vision is highly variable, ranging from blindness to minimal impairment depending upon the severity of the bleeding and vitreous scarring. Lifelong monitoring is important as this is a progressive disease. Patients with milder vision problems may benefit from low vision aids. In some cases surgery on the vitreous and retina can release the traction on the retina, allowing it to reattach. Cataract removal may be beneficial. In mild cases low vision aids may be helpful.
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