Macular Dystrophy, Patterned 2
Patient Information
Characteristics
Background and History
This is an inherited retinal degeneration that affects primarily the area of the retina known as the macula. This region has the highest concentration of cells (rods and cones) that respond to light and gives us our highest visual resolution. There are many heritable conditions that affect the macula.
Clinical Correlations
There is a great deal of variability in the signs and symptoms of patterned macular dystrophy. Most individuals are symptom-free until they are in their late 20s and early 30s although changes in pigmentation of the macula can be seen by the second decade. The pigmentation roughly resembles the shape of butterfly wings and the disorder is sometimes called “butterfly macular dystrophy”. Color vision apparently remains normal but other tests of retinal function such as the electrooculogram (EOG) indicate a generalized disease of the retina.
There are no signs or symptoms outside of the eye.
Genetics
Inheritance
This condition results from a single gene mutation and can be transmitted directly from an affected parent to each child with a 50% probability. The transmission pattern is vertical as expected of an autosomal dominant disorder.
For a somewhat similar disorder see Macular Dystrophy, Patterned 1.
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 only be made by an ophthalmologist usually with the aid of retinal function tests. Individuals with some loss of vision may benefit from low vision aids for specific tasks.
Longevity is not affected.
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