External Ophthalmoplegia, Progressive, with mtDNA Deletions, AR 3
Patient Information
Characteristics
Background and History
This disorder of eye movement was first described by an ophthalmologist, Albrecht Von Graefe, in 1868. A number of genetic disorders cause difficulties in eye movement, known as external ophthalmoplegia, but there are usually associated neurologic manifestations. The type described here is largely limited to the eye.
Clinical Correlations
The onset of signs and symptoms usually occur in those around the age of 40 years when there is droopiness of the eyelids and difficulty moving the eyes fully. These findings are progressive and can be associated with some weakness of arms, legs and shoulders. Standing from a squatting position is difficult as is climbing stairs. Speech can be slurred and swallowing difficulties may be evident.
Genetics
Inheritance
This is an autosomal recessive condition which may occur when a mutation occurs in a specific pair of genes. When each parent is a carrier for a single mutation in one member of the pair, and two such parents pass their mutation to a child (which occurs in 25% of children in such pair matings), he/she may develop this condition.
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
An ophthalmologist is likely the physician to diagnose this condition. A full neurological examination is necessary to rule out other neurologic disorders.
There is no treatment for the full condition but surgery can correct the droopy eyelids.
Two elderly sisters reported with this disorder died of other conditions and the impact of external ophthalmoplegia on longevity is unknown.
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