About Myotonia Congenita
Myotonia Congenita is caused by loss-of-function mutations in the CLCN1 gene encoding the skeletal muscle voltage-gated chloride channel (ClC-1), leading to membrane hyperexcitability and impaired muscle relaxation. The dominant Thomsen form is generally milder, while the recessive Becker form is more severe and may include transient episodic weakness. The hallmark is generalised myotonia (muscle stiffness) that improves with repeated activity — the 'warm-up phenomenon'.
Common Clinical Features
Clinical Trial Eligibility Tips
What to know before applying to Myotonia Congenita trials.
EMG showing myotonic discharges and genetic confirmation of CLCN1 mutation are both typically required; dominant vs recessive status affects which trial cohort you qualify for
Clinical myotonia severity scales and grip myotonia assessment by hand-held dynamometry after prolonged contraction are standard endpoints — document these with a neurologist before applying
Sodium channel blockers (mexiletine) are the current standard of care; washout periods before enrolment are common so plan ahead for medication holds
Patient Resources
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