Cytochrome C Oxidase Deficiency

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Cytochrome C Oxidase Deficiency is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

Cytochrome C Oxidase deficiency is a very rare inherited metabolic disorder characterized by deficiency of the enzyme cytochrome C oxidase (COX), or Complex IV, an essential enzyme that is active in the subcellular structures that help to regulate energy production (mitochondria). Deficiency of COX may be limited (localized) to the tissues of the skeletal muscles or may affect several tissues, such as the heart, kidney, liver, brain, and/or connective tissue (fibroblasts); in other cases, the COX deficiency may be generalized (systemic).

Four distinct forms of Cytochrome C Oxidase deficiency have been identifed. The first form of this disorder is known as COX deficiency, benign infantile mitochondrial myopathy. Affected infants exhibit many of the same symptoms as those with the more severe infantile form of the disease; however, because the COX deficiency is limited (localized) to tissues of the skeletal muscles, they typically do not have heart or kidney dysfunction.

In the second type of the disease, known as COX deficiency, infantile mitochondrial myopathy, because the COX deficiency affects tissues of the skeletal muscles as well as several other tissues, the disorder may be characterized by a generalized weakness of skeletal muscles (myotonia), abnormalities of the heart and kidneys, and/or abnormally high levels of lactic acid in the blood (lactic acidosis). De Toni-Fanconi-Debre syndrome may also be present and may include excessive thirst, excessive urination, and excessive excretion of glucose, phosphates, amino acids, bicarbonate, calcium and water in the urine.

The third form of COX deficiency, known as Leigh's disease (subacute necrotizing encephalomyelopathy), is thought to be a generalized (systemic) form of COX deficiency. Leigh's disease is characterized by progressive degeneration of the brain and dysfunction of other organs of the body including the heart, kidneys, muscles, and liver. Symptoms may include loss of previously acquired motor skills, loss of appetite, vomiting, irritability, and/or seizure activity. As Leigh's disease progresses, symptoms may also include generalized weakness; loss of muscle tone (hypotonia); and/or episodes of lactic acidosis.

In the fourth form of COX deficiency, known as COX deficiency French-Canadian type, the COX deficiency affects tissues of the skeletal muscles, connective tissue, and, in particular, the brain (Leigh's disease) and the liver. Affected infants and children may demonstrate developmental delays, diminished muscle tone (hypotonia), crossing of the eyes (strabismus), Leigh's disease, and/or episodes of lactic acidosis.

Most cases of COX deficiency are inherited as autosomal recessive genetic diseases. Rarely, COX deficiency occurs as the result of a new or inherited abnormality (mutation) in a mitochondrial gene.

Supporting Organizations

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building
176 Nantwich Road
Crewe, CW2 6BG
United Kingdom
Tel: 4408452412173
Fax: 4408452412174
Email: enquiries@climb.org.uk
Website: http://www.CLIMB.org.uk

Childhood Liver Disease Research and Education Network

c/o Joan M. Hines, Research Administrator
Children's Hospital Colorado
Aurora, CO 80045
Tel: (720)777-2598
Fax: (720)777-7351
Email: joan.hines@childrenscolorado.org
Website: http://www.childrennetwork.org

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
Website: http://rarediseases.info.nih.gov/GARD/

Lactic Acidosis Support Trust

1A Whitley Close
Cheshire, CW10 0NQ
United Kingdom
Tel: 160683719
Fax: 1606837198

MitoAction

PO Box 51474
Boston, MA 02205
Tel: (888)648-6228
Fax: (888)648-6228
Email: info@mitoaction.org
Website: http://www.MitoAction.org

NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison
Bldg 31, Rm 9A06
Bethesda, MD 20892-2560
Tel: (301)496-3583
Email: NDDIC@info.niddk.nih.gov
Website: http://www2.niddk.nih.gov/

United Mitochondrial Disease Foundation

8085 Saltsburg Road Suite 201
Pittsburgh, PA 15239
United States
Tel: (412)793-8077
Fax: (412)793-6477
Tel: (888)317-8633
Email: info@umdf.org
Website: http://www.umdf.org

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

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This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  4/29/2015
Copyright  2015 National Organization for Rare Disorders, Inc.