Fundus Albipunctatus
Patient Information
Characteristics
Background and History
This disorder is often included in a group of rare hereditary disorders known as ‘flecked retina syndromes’. The designation is based on the presence of uniform small white or yellow lesions, usually dots, in the retina (the light sensing tissue lining the inside of the eye).
Clinical Correlations
In this condition night blindness is the major symptom and usually the only one in children and young people. By middle age, however, some vision may be lost. The retina has uniformly scattered white dots throughout. A functional test of the retina, known as an ERG or electroretinogram, often shows early damage to the light sensing cells of the retina, known as the rods and cones. Fundus albipunctatus is not considered to be a progressive disorder although some older and rarely younger individuals do experience some vision loss.
No systemic disease is present.
Genetics
Inheritance
This condition is almost always inherited in an autosomal recessive pattern. It results when individuals inherited two copies of a mutation, one from each parent. Parents who have only one copy are asymptomatic but they confer a risk of one in four (25%) to each of their children to develop the eye problem.
Other families have been reported with an autosomal dominant pattern of transmission in which case affected parents have a 50% risk that each child will inherit the same condition.
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
The diagnosis is made by an eye doctor and is confirmed by the ERG test. Longevity is normal. Recent evidence suggests that high doses of Vitamin A may improve night vision but it does not cure the eye disease. Low vision aids can be helpful when vision is decreased.
Printer Friendly Version: Ctrl/Cmd+P