Corneal Dystrophy, Avellino Type
Patient Information
Characteristics
Background and History
Early reported families having features of both lattice and granular corneal disease were traced to the Avellino district of Italy from which the name is derived. More recent reports have described families from around the world.
Clinical Correlations
The cornea is the clear windshield of the eye and a number of gene mutations cause progressive disease, usually in the form of increasing cloudiness resulting in loss of sharpness of vision. Some individuals also experience recurrent erosions, a type of scratch, on the surface which can be painful and slow to heal. This can cause further clouding of vision as well as discomfort from lights due to glare.
Avellino type of corneal disease actually has features of two other dystrophies, granular and lattice dystrophies which should be consulted for further information. No systemic abnormalities are associated. There is considerable doubt that the Avellino type of corneal disease is a unique entity based on genetic and clinical evidence. Many experts consider this to be a variation of lattice and granular dystrophies as it has features of both.
Genetics
Inheritance
This form of corneal disease, like that of lattice and granular and some others, is inherited in an autosomal dominant pattern. In this inheritance pattern, the mutant gene and disease are passed directly from parent to child resulting in a vertical pattern.
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
The diagnosis can be made by an ophthalmologist by examination of the cornea. Vision varies widely but is increasingly impaired over time. A corneal transplant can help restore vision but the corneal deposits tend to recur after several years.
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