Optic Atrophy 6
Patient Information
Characteristics
Background and History
The optic nerve connects the eye to the brain and carries visual signals from the retina that enables us to see. Consequently, any disease that damages this nerve can result in vision loss. A number of gene mutations lead to defects of such nerve conduction which may begin with damage to the nerve cells of the retina.
Clinical Correlations
Optic atrophy 6 usually leads to symptoms before the age of 6 years and is slowly progressive. It is also a bilateral disease. Vision loss seems to stop at about legal blindness levels (20/200) with no recovery. An unusual feature of optic atrophy 6 is the presence of increased light sensitivity. Red-green color confusion is common. This form of optic atrophy causes only vision symptoms and no other parts of the body seem to be affected.
Genetics
Inheritance
This is an autosomal recessive disorder resulting from the presence of two mutations, one contributed by each normal carrier parent. A single French Canadian family has been reported with this disorder. The parents were related to each other.
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
The diagnosis is usually made by an ophthalmologist or sometimes by a neurologist. The prognosis is highly variable but once the optic nerve is damaged, the vision loss is not reversible. No treatment is available for the optic nerve damage but low vision aids can be helpful for everyday tasks.
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