Cytochrome C Oxidase Deficiency

National Organization for Rare Disorders, Inc.

Important
It is possible that the main title of the report Cytochrome C Oxidase Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • COX deficiency
  • deficiency of mitochondrial respiratory chain complex IV
  • complex IV deficiency

Disorder Subdivisions

  • Leigh's syndrome (subacute necrotizing encephalomyelopathy)
  • COX deficiency French-Canadian type
  • COX deficiency, benign infantile mitochondrial myopathy type
  • COX deficiency, infantile mitochondrial myopathy type

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-Debré 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.
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Resources

CLIMB (Children Living with Inherited Metabolic Diseases)
Climb Building
176 Nantwich Road
Crewe, Intl CW2 6BG
United Kingdom
Tel: +44 870 7700 325
Fax: +44 870 7700 327
Email: info.svcs@climb.org.uk
Internet: http://www.CLIMB.org.uk

United Mitochondrial Disease Foundation (UMDF)
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
Internet: http://www.umdf.org

Lactic Acidosis Support Trust
1A Whitley Close
Middlewich
Cheshire, CW10 0NQ
United Kingdom
Tel: 0160683719
Fax: 01606837198

NIH/National Institute of Diabetes, Digestive & Kidney Diseases
Endocrine Diseases Metabolic Diseases Branch
2 Information Way
Bethesda, MD 20892-3570
Tel: (301)654-3810
Fax: (301)496-7422
Email: NDDIC@info.niddk.nih.gov
Internet: http://www.niddk.nih.gov

MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
USA
Tel: (920)336-5333
Fax: (920)339-0995
Tel: (877)336-5333
Email: mums@netnet.net
Internet: http://www.netnet.net/mums/

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
TDD: (888)205-3223
Email: ordr@od.nih.gov
Internet: http://rarediseases.info.nih.gov/Default.aspx

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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