Complex IV Deficiency / COX Deficiency

Mitochondrial Disease Types

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

Two main variants:

  1. Fatal infantile myopathy: may begin soon after birth and accompanied by hypotonia, weakness, lactic acidosis, ragged-red fibers, respiratory failure, and kidney problems.

  2. 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