Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with Eleplan3-methylglutaconic aciduria type 9
ORPHA:505216Disease
Also called 3-methylglutaconic aciduria-epilepsy-spasticity-severe intellectual disability syndrome · MGA9
What it is
A rare organic aciduria characterized by early onset of global developmental delay with severe intellectual disability, seizures, and 3-methylglutaconic aciduria. Additional features are hypotonia, hyperactivity and aggressive behavior, optic atrophy, or spasticity. Brain imaging may show generalized cerebral atrophy and white matter abnormalities.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Infancy
- Inheritance
- Autosomal recessive
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
18- 3-Methylglutaconic aciduriaDiagnostic criterion
- Abnormality of speech or vocalization
- Aggressive behavior
- Cerebral atrophy
- Clonus
- Decreased activity of mitochondrial ATP synthase complexDiagnostic criterion
- Delayed ability to walk
- Delayed gross motor development
- Diffuse white matter abnormalities
- EEG abnormality
- Encephalopathy
- Failure to thrive
- Hypotonia
- Increased circulating lactate concentration
- Intellectual disability, severe
- Muscle weakness
- Slender build
- Status epilepticus
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
Powered by Eleplan
A rare diagnosis is just the start. Eleplan keeps the whole care plan in one place.
Diagnoses, medications, documents, appointments, and the whole care team — organized and always in sync, so you are not retelling the same story to every new specialist. With Ellie, your AI care assistant, on top of it. Free to start.