Disease Directory MELAS Syndrome
Mitochondrial

MELAS Syndrome

Also known as: mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes, MT-TL1 mutation

Prevalence

Approximately 1–9 per 100,000

Onset

Childhood to early adulthood (typically before age 40)

Type

Rare mitochondrial disease

Gene

MT-TL1, MT-ND5 (mtDNA)

About MELAS Syndrome

MELAS syndrome is a maternally inherited mitochondrial disorder characterised by stroke-like episodes, encephalopathy, lactic acidosis, and a range of systemic manifestations including myopathy and diabetes. The most common causative variant is m.3243A>G in the MT-TL1 gene, which impairs mitochondrial protein synthesis globally. The stroke-like episodes are distinct from ischaemic stroke and are thought to result from impaired mitochondrial energy production in neurons rather than vascular occlusion.

Common Clinical Features

Stroke-like episodes with focal neurological deficits Seizures Lactic acidosis Sensorineural hearing loss Myopathy and exercise intolerance Diabetes mellitus Migraine-like headaches

Clinical Trial Eligibility Tips

What to know before applying to MELAS Syndrome trials.

Mutation heteroplasmy level in blood or urine can influence eligibility; some trials require a minimum heteroplasmy percentage confirmed by next-generation sequencing.

Acute stroke-like episodes may disqualify enrolment during the active event; apply during a clinically stable inter-episode period.

Baseline plasma lactate, brain MRI, and audiological assessments are standard pre-screening requirements; ensure results are current.

Patient Resources

Patient Organization

United Mitochondrial Disease Foundation

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Natural History Registry

North American Mitochondrial Disease Consortium (NAMDC) Registry

Join registry ↗

Orphanet

European reference resource for rare diseases (ORPHA:550)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

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Find recruiting MELAS Syndrome trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for MELAS Syndrome. Updated daily.

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