RecruitingNCT05554835
Mitochondrial
MERRF Syndrome
Also known as myoclonic epilepsy with ragged red fibres, MT-TK mutation
MERRF syndrome is a maternally inherited mitochondrial disorder characterised by myoclonic epilepsy, cerebellar ataxia, myopathy with ragged red fibres on muscle biopsy, and progressive neurological deterioration. The most common causative
ORPHA:551 ↗Gene MT-TK (mtDNA)Prevalence Rare; estimated fewer than 1 in 400,000Onset Childhood to early adulthood
2
studies recruiting now
as of 7 Sept 2026
6
studies registered in total
as of 7 Sept 2026
5
countries with a recruiting site
as of 7 Sept 2026
26 Sept 2022
most recent study posted
among recruiting studies
Recruiting trials
RecruitingNCT01694940
North American Mitochondrial Disease Consortium Patient Registry and Biorepository (NAMDC)
Showing the 2 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
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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 MERRF Syndrome
MERRF syndrome is a maternally inherited mitochondrial disorder characterised by myoclonic epilepsy, cerebellar ataxia, myopathy with ragged red fibres on muscle biopsy, and progressive neurological deterioration. The most common causative mutation is m.8344A>G in MT-TK, which encodes mitochondrial tRNA-Lys and disrupts oxidative phosphorylation. The clinical spectrum is broad, ranging from mild myoclonus to severe multisystem disease, influenced by mutation heteroplasmy levels across tissues.
Common clinical features
Myoclonus (stimulus-sensitive jerking)Generalised seizuresCerebellar ataxiaMyopathy with ragged red fibresSensorineural hearing lossDementia or cognitive declineShort stature and exercise intolerance
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Before you apply
Things trial teams commonly ask about for MERRF Syndrome. Not eligibility rules; those are set by each study.
- Muscle biopsy showing ragged red fibres and/or confirmed MT-TK mutation is the primary diagnostic requirement for most MERRF studies; ensure pathology reports are available.
- Heteroplasmy levels in muscle tissue are more informative than blood for this disorder; request tissue-specific genetic testing if blood results are inconclusive.
- Anti-epileptic drug regimens may interact with investigational agents; provide a complete medication list including valproate, which is often contraindicated in mitochondrial disease.
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).