myotonia fluctuans
Findings
No curated finding names myotonia fluctuans yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Myotonia fluctuans (MF) is a form of potassium-aggravated myotonia (PAM) which is cold insensitive, dramatically fluctuating and profoundly worsened by potassium ingestion.
Definition from the Mondo Disease Ontology (MONDO:0020481), read 2026-09-29. CC BY 4.0.
Features
21 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- EMG: myotonic dischargesHPOHP:0100284
- Very frequent (80% to 99% of cases)
- Muscle stiffnessHPOHP:0003552
- Very frequent (80% to 99% of cases)
- Exercise-induced muscle stiffnessHPOHP:0008967
- Frequent (30% to 79% of cases)
- Myotonia of the lower limbHPOHP:0012902
- Frequent (30% to 79% of cases)
- Myotonia of the upper limbHPOHP:0012903
- Frequent (30% to 79% of cases)
- Spasticity of facial musclesHPOHP:0002491
- Frequent (30% to 79% of cases)
- Blurred visionHPOHP:0000622
- Occasional (5% to 29% of cases)
- DiplopiaHPOHP:0000651
- Occasional (5% to 29% of cases)
- FatigueHPOHP:0012378
- Occasional (5% to 29% of cases)
- Handgrip myotoniaHPOHP:0012899
- Occasional (5% to 29% of cases)
- MyalgiaHPOHP:0003326
- Occasional (5% to 29% of cases)
- Myotonia of the faceHPOHP:0012900
- Occasional (5% to 29% of cases)
Reported absent (1)
- Cold-sensitive myotoniaHPOHP:0012904
Show the remaining 9
- ApneaHPOHP:0002104
- Very rare (1% to 4% of cases)
- Choking episodesHPOHP:0030842
- Very rare (1% to 4% of cases)
- Gait disturbanceHPOHP:0001288
- Very rare (1% to 4% of cases)
- LaryngospasmHPOHP:0025425
- Very rare (1% to 4% of cases)
- Myotonia with warm-up phenomenonHPOHP:0003740
- Very rare (1% to 4% of cases)
- Neonatal hypotoniaHPOHP:0001319
- Very rare (1% to 4% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- SCN4AHGNC:10591
- Supportive · Orphanet · Autosomal dominant · 2021
Where it sits
- A kind of
Other names
3 names
Resolves to: myotonia fluctuans
- Also called
- exercise-induced delayed-onset myotoniaFluctuating myotoniaMF