RecruitingNCT07700225
Neuromuscular
Myotonia Congenita
Also known as Thomsen disease, Becker myotonia, CLCN1 myotonia
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 for
ORPHA:614 ↗Gene CLCN1Prevalence 1 in 25,000 to 1 in 100,000Onset Infancy to early childhoodAutosomal dominant (Thomsen) or autosomal recessive (Becker)
14
studies recruiting now
as of 7 Sept 2026
45
studies registered in total
as of 7 Sept 2026
12
countries with a recruiting site
as of 7 Sept 2026
13 Jul 2026
most recent study posted
among recruiting studies
Recruiting trials
RecruitingPhase 3NCT07486934
Efficacy, Safety, and Tolerability of Zeleciment Basivarsen (DYNE-101) in Participants With Myotonic Dystrophy Type 1
RecruitingNot applicableNCT07580365
VirtualPark_Pediatric
RecruitingNCT06747884
Trial Readiness and Endpoint Assessment in Pediatric Myotonic Dystrophy Extension
RecruitingNCT07502989
Muscle Health Measurements Using Electrical Impedance Myography
Showing the 5 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
See all 14 recruiting studiesWhere recruiting studies are running
Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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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
Generalised muscle stiffness and myotonia from infancyWarm-up phenomenon (stiffness improves with repeated movement)Muscle hypertrophy giving an athletic appearanceTransient episodic weakness (more prominent in Becker myotonia)Eyelid myotonia (difficulty opening eyes rapidly)Cold-exacerbated myotoniaNormal creatine kinase or mildly elevated
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Before you apply
Things trial teams commonly ask about for Myotonia Congenita. Not eligibility rules; those are set by each study.
- 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
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).