Flecked Retina Syndromes
Patient Information
Characteristics
Background and History
There is a group of diseases characterized by yellow-white dots in the retina (the tissue lining the inside of the eye that responds to light). These have not been well characterized clinically but night blindness is a symptom in some but not all entities in this category of disease.
Clinical Correlations
Night blindness is common in these disorders. It may be stationary or progressive. Some patients experience loss of daytime vision as well but others do not. This group of flecked retina disorders, so named because of the appearance of yellowish/white spots in the retina (the light sensing tissue in the eye).
Genetics
Inheritance
This category of disease consists of at multiple types and genetic studies suggest that more may be found. These conditions may be inherited in an autosomal dominant or an autosomal recessive pattern (see model pedigrees). Mutations in several genes are involved.
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
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
These disorders can only be diagnosed by an ophthalmologist based on the history, appearance of the retina, and results of an electroretinogram (ERG) test. No systemic disease is associated with these conditions. Recent reports indicate that high oral doses of beta-carotene may lead to an improvement in night blindness. Low vision aids are available for those with vision loss but these are not needed in many patients.
Web Resources
Printer Friendly Version: Ctrl/Cmd+P