Progressive External Ophthalmoplegia is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Progressive External Ophthalmoplegia (PEO) is a mitochondrial disorder characterized by progressive loss of eye movements, ptosis (drooping eyelids), and often the presence of multiple mitochondrial DNA (mtDNA) deletions in skeletal muscle. [2]
Progressive External Ophthalmoplegia represents one of the most common manifestations of mitochondrial DNA deletion syndromes. The condition is typically adult-onset and progresses gradually over decades, affecting the extraocular muscles responsible for eye movements. [3]
The most common genetic forms involve mutations in: [4]
| Gene | Protein | Inheritance | Notes | [^6]
|------|---------|-------------|-------| [^7]
| TWNK (PEO1) | Twinkle helicase | AD | Most common cause | [^8]
| POLG | DNA polymerase gamma | AD | Most common cause |
| POLG2 | POLG accessory subunit | AD | Rare |
| RRM2B | p53-inducible RRM2B | AD | Rare |
| Gene | Protein | Notes |
|---|---|---|
| TK2 | Thymidine kinase 2 | mtDNA depletion |
| RRM2B | RRM2B | Severe early-onset form |
| OPA1 | OPA1 | Plus optic atrophy |
Many cases appear sporadic due to spontaneous mtDNA deletions in somatic cells.
| Symptom | Description | Onset |
|---|---|---|
| Ophthalmoplegia | Progressive limitation of eye movements | Gradual, bilateral |
| Ptosis | Drooping eyelids | Often first sign |
| Diplopia | Double vision | Less common |
| Reduced eye movements | Upward gaze first affected | Progressive |
| Type | Features |
|---|---|
| Pure PEO | Isolated eye movement deficits |
| PEO-plus | PEO with additional systemic features |
| Kearns-Sayre syndrome | PEO, cardiac conduction, cerebellar ataxia |
| Treatment | Evidence | Notes |
|---|---|---|
| Coenzyme Q10 | Moderate | May improve some patients |
| L-carnitine | Variable | Supports mitochondrial function |
| Vitamin supplements | Limited | B-complex, vitamin E |
| Exercise training | Beneficial | Avoid overexertion |
The study of Progressive External Ophthalmoplegia has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
This section highlights recent publications relevant to this disease.
A Novel Truncating Pathogenic Variant in RRM2B in a Kurdish Family With Autosomal-Dominant Chronic Progressive External Ophthalmoplegia Plus (PEOA5). ↩︎
Outcomes of kidney transplantation in three patients with single large-scale mitochondrial DNA deletion syndromes. ↩︎
Volumetric brain analysis and associated retinal thinning in autosomal dominant optic atrophy patients. ↩︎
Clinical and Genotypic Spectrum of Twinkle-Related Disorders: Insights From a Multinational Cohort Study. ↩︎