Rare diseases · Sign or symptom
Muscle flaccidity
HP:0010547
What it means
A type of paralysis in which a muscle becomes soft and yields to passive stretching, which results from loss of all or practically all peripheral motor nerves that innervated the muscle. Muscle tone is reduced and the affected muscles undergo extreme atrophy within months of the loss of innervation.
Rare diseases that can present with this11
Very common80–99%
4Common30–79%
4The 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
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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.