Disease Directory Chronic Progressive External Ophthalmoplegia
Mitochondrial

Chronic Progressive External Ophthalmoplegia

Also known as: CPEO, progressive external ophthalmoplegia, PEO

Prevalence

Approximately 1 in 100,000

Onset

Variable; typically adolescence to adulthood

Type

Rare mitochondrial myopathy

Gene

mtDNA deletion, POLG, PEO1

About Chronic Progressive External Ophthalmoplegia

Chronic progressive external ophthalmoplegia is a mitochondrial myopathy characterised by slowly progressive bilateral ptosis and ophthalmoplegia with preserved pupillary reflexes, caused by dysfunction of the extraocular muscles. It may occur as an isolated condition or as part of broader mitochondrial syndromes such as Kearns-Sayre syndrome. The genetic basis is heterogeneous, involving both primary mtDNA deletions and nuclear gene mutations (most commonly POLG) that cause secondary mtDNA instability.

Common Clinical Features

Bilateral ptosis (often the presenting feature) Progressive limitation of extraocular eye movements Diplopia (less common due to symmetrical progression) Proximal limb myopathy Exercise intolerance Dysphagia (in severe or syndromic forms) Ragged red fibres on muscle biopsy

Clinical Trial Eligibility Tips

What to know before applying to Chronic Progressive External Ophthalmoplegia trials.

Genetic characterisation is essential: CPEO caused by POLG mutations may have different disease courses and trial eligibility compared to mtDNA deletion forms; pursue comprehensive testing.

Ophthalmological measurements including Hertel exophthalmometry, ocular motility charts, and ptosis grading should be documented at a specialist neuro-ophthalmology centre.

Overlapping features with Kearns-Sayre syndrome should be systematically excluded (cardiac conduction, CSF protein, pigmentary retinopathy) as this affects both diagnosis and applicable trials.

Patient Resources

Patient Organization

United Mitochondrial Disease Foundation

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Natural History Registry

North American Mitochondrial Disease Consortium (NAMDC) Registry

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Orphanet

European reference resource for rare diseases (ORPHA:644)

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NORD

National Organization for Rare Disorders

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Find recruiting Chronic Progressive External Ophthalmoplegia trials

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