Cytochrome C Oxidase Deficiency
National Organization for Rare Disorders, Inc.
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.
- COX deficiency
- deficiency of mitochondrial respiratory chain complex IV
- complex IV deficiency
- Leigh's syndrome (subacute necrotizing encephalomyelopathy)
- COX deficiency French-Canadian type
- COX deficiency, benign infantile mitochondrial myopathy type
- COX deficiency, infantile mitochondrial myopathy type
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.
CLIMB (Children Living with Inherited Metabolic Diseases)
176 Nantwich Road
Crewe, Intl CW2 6BG
Tel: +44 870 7700 325
Fax: +44 870 7700 327
United Mitochondrial Disease Foundation (UMDF)
8085 Saltsburg Road
Pittsburgh, PA 15239
Lactic Acidosis Support Trust
1A Whitley Close
Cheshire, CW10 0NQ
NIH/National Institute of Diabetes, Digestive & Kidney Diseases
Endocrine Diseases Metabolic Diseases Branch
2 Information Way
Bethesda, MD 20892-3570
MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
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