Foveal Hypoplasia 2
Patient Information
Characteristics
Background and History
Foveal hypoplasia is a condition that primarily or solely involves a specialized area of the retina which we use for our sharpest vision since it contains the densest concentration of light receptors known as rods and cones. It is a very small area directly in our line of sight in the back of the eye.
Clinical Correlations
In most cases this underdevelopment of the fovea is the only abnormality found. It is present at birth and results in poor vision along with nystagmus (roving movements of the eye) and strabismus (where the eyes do not align properly). This is a nonprogressive disorder. In a few patients there may be mild anomalies in the anterior segment of the eye but these usually do not cause any vision problems.
There are no consistent systemic problems.
Genetics
Inheritance
Mutations in both members of a specific pair of genes are responsible for this disorder. Parents who carry only a change (mutation) in one member of the pair are clinically normal but when both parents carry the single mutation they together confer a 25% risk to each child for this disorder.
Pedigree
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
Ophthalmologists are important to the diagnosis of this disorder. A specialized imaging technique known as OCT (optical coherence tomography) can confirm the anatomic anomaly of the fovea.
There is no known treatment. Low vision devices are helpful for near (reading) vision and special education would likely be beneficial for children and young adults. There is no impact on longevity.
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