Progressive external ophthalmoplegia is a disorder of the mitochondria. It is characterized by multiple mitochondrial DNA deletions in skeletal muscle.
The most common clinical features include adult onset of weakness of the external eye muscles
) and exercise intolerance.
Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, clinical depression, hypogonadism, and parkinsonism.
Both autosomal dominant and autosomal recessive inheritance can occur, autosomal recessive inheritance being more severe. However, in most cases, PEO occurs due to a sporadic deletion or duplication within the mitochondrial DNA. A transmission from the mother to the progeny appears only in few cases.
It is usually diagnosed by neurologists
There is no proven treatment, but experimental agents such as coenyzme Q10
may provide benefit. (Reference needed.)