Complex IV Deficiency / COX Deficiency
Long Name: Cytochrome c oxidase deficiency is caused by a defect in Complex IV of the respiratory chain.
Symptoms: Two major forms:
Encephalomyopathy
Typically normal for the first 6 to 12 months of life and then show developmental regression, ataxia, lactic acidosis, optic atrophy, ophthalmoplegia, nystagmus, dystonia, pyramidal signs, and respiratory problems. Frequent seizures. May cause Leigh Syndrome.
Myopathy
- Fatal infantile myopathy: may begin soon after birth and accompanied by hypotonia, weakness, lactic acidosis, ragged-red fibers, respiratory failure, and kidney problems.
- Benign infantile myopathy: may begin soon after birth and accompanied by hypotonia, weakness, lactic acidosis, ragged-red fibers, respiratory problems, but (if the child survives) followed by spontaneous improvement.
Treatment: As with all mitochondrial diseases, there is no cure for Complex I deficiency. A variety of treatments, which may or may not be effective, can include such metabolic therapies as: riboflavin, thiamine, biotin, co-enzyme Q10, carnitine, and the ketogenic diet. Therapies for the infantile multisystem form have been unsuccessful.
The clinical course and prognosis for Complex I patients is highly variable and may depend on the specific genetic defect, age of onset, organs involved, and other factors.
Cause: Probably autosomal recessive
Links: https://rarediseases.info.nih.gov/diseases/48/cytochrome-c-oxidase-deficiency