Rare diseases · Sign or symptom
Decreased activity of mitochondrial complex I
HP:0011923
What it means
A reduction in the activity of the mitochondrial respiratory chain complex I, which is part of the electron transport chain in mitochondria.
Rare diseases that can present with this14
Common30–79%
9- Autosomal recessive spastic paraplegia type 74
- Combined oxidative phosphorylation defect type 27
- Fatal infantile lactic acidosis with methylmalonic aciduria
- Hypertrophic cardiomyopathy with kidney anomalies due to mitochondrial DNA mutation
- Leigh syndrome
- Mitochondrial hypertrophic cardiomyopathy with lactic acidosis due to MTO1 deficiency
- Mitochondrial myopathy with reversible cytochrome C oxidase deficiency
- Multiple mitochondrial dysfunctions syndrome type 2
- Multiple mitochondrial dysfunctions syndrome type 3
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Respiratory complex I deficiency
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.