Cytochrome c oxidase deficiency

What is cytochrome C oxidase (COX) deficiency?

Cytochrome C oxidase deficiency (COX deficiency) is a condition that can affect several parts of the body including the skeletal muscles, heart, brain and liver. There are four types of COX deficiency differentiated by symptoms and age of onset: benign infantile mitochondrial type, French-Canadian type, infantile mitochondrial myopathy type, and Leigh syndrome. The range and severity of signs and symptoms can vary widely among affected individuals (even within the same subtype and same family) and depend on the form of the condition present. Features in mildly affected individuals may include muscle weakness and hypotonia; in more severely affected individuals, brain dysfunction; heart problems; an enlarged liver; lactic acidosis; and/or a specific group of features known as Leigh syndrome may also be present. COX deficiency is caused by mutations in any of at least 14 genes; the inheritance pattern depends on the gene involved. The condition is frequently fatal in childhood, but mildly affected individuals may survive into adolescence or adulthood.

Last updated on 05-01-20

Do children with cytochrome C oxidase (COX) deficiency typically lose previously acquired skills?

Loss of skills, also known as developmental regression, can occur in individuals with COX deficiency associated with Leigh syndrome. Individuals may have developmental delays or intellectual disabilities, but regression is not present in all individuals with this disorder. It is not possible to determine if a particular child will experience future regression.

Last updated on 05-01-20

Can visual impairment progress to blindness in people with cytochrome C oxidase (COX) deficiency?

Some individuals with COX deficiency develop optic nerve atrophy, which can significant reduce vision. We cannot comment on whether this particular child will eventually lose her vision.

Last updated on 05-01-20

What is the life expectancy for cytochrome C oxidase (COX) deficiency?

There are varying degrees of severity in COX deficiency. Individuals with more severe cases may die during infancy, while those with less severe cases have lived into adulthood. We cannot predict the life expectancy for a particular child.

Last updated on 05-01-20

How might cytochrome C oxidase deficiency be treated?

There is currently no cure for cytochrome C oxidase (COX) deficiency. Management of all forms of COX deficiency generally focuses on the specific symptoms present in the affected individual and is largely supportive. The goals of treatment are to improve symptoms and slow progression of the disease; the effectiveness of treatment varies with each individual. Treatment generally does not reverse any damage that has already occurred. Prognosis varies depending on the form of COX deficiency present. Individuals with benign infantile mitochondrial myopathy may experience spontaneous recovery (although early diagnosis and intensive treatment is still needed until this point), while there may be rapid demise in individuals with Leigh syndrome.

It is often recommended that individuals with mitochondrial disorders such as COX deficiency avoid fasting. Dehydration due to vomiting or illness may be treated with intravenous fluid if the individual is not able to take fluids orally. Seizures are typically controlled with anticonvulsants. Some affected individuals may benefit from physical, occupational, and speech therapies that are specifically tailored to their needs. Dietary supplements including certain vitamins and cofactors have shown varying degrees of benefit in individual cases.

Individuals interested in specific management recommendations for themselves or relatives should speak with their healthcare providers.

Last updated on 05-01-20

Name: United Mitochondrial Disease Foundation 8085 Saltsburg Road, Suite 201
Pittsburgh, PA, 15239 , United States
Phone: +1-412-793-8077 Toll Free: 1-888-317-8633 Fax : +1-412-793-6477 Email: Url:
Name: MitoAction PO Box 51474
Boston, MA, 02205, United States
Phone: 1-888-MITO-411 (648-6411) for support line Toll Free: 1-888-648-6228 Email: Url:

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