About Mitochondrial Complex IV Deficiency
Mitochondrial complex IV deficiency is caused by mutations in genes encoding cytochrome c oxidase (COX) subunits or assembly factors, impairing electron transfer from cytochrome c to molecular oxygen and thereby reducing ATP synthesis. SURF1 mutations are the most common nuclear cause and are strongly associated with Leigh syndrome, while SCO2 mutations typically present with fatal infantile cardioencephalomyopathy. Clinical presentations are broad, reflecting both genotype and residual enzyme activity levels.
Common Clinical Features
Clinical Trial Eligibility Tips
What to know before applying to Mitochondrial Complex IV Deficiency trials.
Tissue-specific COX enzyme activity assay (in muscle or liver) is required for biochemical diagnosis; specify the tissue analysed when applying, as activity levels vary between tissues.
SURF1 mutation status is a common stratification variable given its strong Leigh syndrome association; ensure full sequencing of the SURF1 gene is performed.
Cardiac assessment including echocardiography is often a prerequisite given the risk of cardiomyopathy, particularly in SCO2-related disease; have recent cardiac imaging available.
Patient Resources
Natural History Registry
North American Mitochondrial Disease Consortium (NAMDC) Registry
Join registry ↗Find recruiting Mitochondrial Complex IV Deficiency trials
Search 500,000+ studies from ClinicalTrials.gov, filtered for Mitochondrial Complex IV Deficiency. Updated daily.