Rare diseases · Sign or symptom
Neck muscle weakness
Floppy neck
HP:0000467
What it means
Decreased strength of the neck musculature.
Rare diseases that can present with this22
Very common80–99%
5Common30–79%
6Sometimes5–29%
9- Autosomal dominant Charcot-Marie-Tooth disease type 2Z
- Autosomal recessive spastic paraplegia type 35
- Childhood-onset nemaline myopathy
- Genetic recurrent myoglobinuria
- GMPPB-related limb-girdle muscular dystrophy R19
- Kearns-Sayre syndrome
- Neutral lipid storage disease with myopathy
- Spinocerebellar ataxia type 35
and 1 more in this range
The 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, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Flaccid neck
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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.