Vitreoretinopathy refers to a condition in the back of the eye in which a primary retinal 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. EVR2 is one of several disorders that result from this process.
There is considerable clinical variability in the signs and symptoms, even within families. It usually affects both eyes but can be quite asymmetrical. The condition begins at birth and may progress rapidly to blindness in infants and young children. More frequently, the disease process is arrested at some point and many adults are asymptomatic and the diagnosis is only made during a routine eye examination. Cataracts may develop. The most serious result from the disease process is a retinal detachment which, if untreated, leads to blindness.
Premature infants are at risk for a condition called retinopathy of prematurity which clinically resembles familial exudative vitreoretinopathy sometimes but, of course, the history of premature birth and administration of oxygen can help to distinguish the two.
Familial exudative vitreoretinopathy can be inherited in autosomal dominant, autosomal recessive, and X-linked patterns as a result of mutations in at least 3 and possibly 4 genes.
In EVR2, the mutant gene is on the X-chromosome. Only one mutation is required for the disease to become manifest. Since males have only one X-chromosome, and the second normal X-chromosome in females neutralizes the mutant gene on the other chromosome, only males generally have this form of familial exudative vitreoretinopathy. They cannot pass the condition to their children but half of the daughters will be clinically normal carriers of the mutation.
The diagnosis can only be made by an ophthalmologist by direct examination of the eye. The prognosis is unpredictable for some patients have minimal or no symptoms while other eyes become blind. Various surgical treatments for cataracts and retinal disease can be beneficial in the restoration of vision. There are no associated abnormalities in the rest of the body.