Rare diseases · Sign or symptom
Ragged-red muscle fibers
HP:0003200
What it means
An abnormal appearance of muscle fibers observed on muscle biopsy. Ragged red fibers can be visualized with Gomori trichrome staining as irregular and intensely red subsarcolemmal zones, whereas the normal myofibrils are green. The margins of affect fibers appear red and ragged. The ragged-red is due to the accumulation of abnormal mitochondria below the plasma membrane of the muscle fiber, leading to the appearance of a red rim and speckled sarcoplasm.
This finding is demonstrated by muscle biopsy. Note that additionally, muscle fibers with mitochondrial proliferation stain darkly for succinic dehydrogenase (SDH).
Rare diseases that can present with this21
Very common80–99%
5Common30–79%
12- Autosomal dominant mitochondrial myopathy with exercise intolerance
- Autosomal dominant progressive external ophthalmoplegia
- Autosomal recessive progressive external ophthalmoplegia
- Combined oxidative phosphorylation defect type 27
- Glycogen storage disease due to muscle and heart glycogen synthase deficiency
- Kearns-Sayre syndrome
- Mitochondrial DNA-related cardiomyopathy and hearing loss
- Mitochondrial DNA-related progressive external ophthalmoplegia
- Mitochondrial neurogastrointestinal encephalomyopathy
- Progressive external ophthalmoplegia-myopathy-emaciation syndrome
- Sensory ataxic neuropathy-dysarthria-ophthalmoparesis syndrome
- Spastic paraplegia type 7
Sometimes5–29%
3The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Mitochondrial proliferation in muscle tissue · Ragged red muscle fibers · Ragged red muscle fibres · Ragged-red fibers · Ragged-red fibres · Ragged-red muscle fibres
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.