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Mitochondrial complex III deficiency

Other Names for this Disease
  • Complex 3 mitochondrial respiratory chain deficiency
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Mitochondrial complex III deficiency is one of several conditions caused by dysfunction of mitochondria, which are specialized compartments in cells that generate more than 90% of the energy required by the body.[1] It is a severe, multisystem disorder that includes features such as lactic acidosis, hypotonia, hypoglycemia, failure to thrive, encephalopathy, and delayed psychomotor development. Involvement of internal organs, including liver disease and renal tubulopathy, may also occur. Symptoms typically begin at birth. Many affected individuals die in early childhood, but some have survived longer. It is generally caused by mutations in nuclear DNA in the BCS1L, UQCRB and UQCRQ genes and inherited in an autosomal recessive manner. However, it may also be caused by mutations in mitochondrial DNA in the MTCYB gene, which is passed down maternally or occurs sporadically and may result in a milder form of the condition.[2] Treatment generally focuses on alleviating symptoms and/or slowing down the progression of the disease, and effectiveness can vary among individuals.[3]
Last updated: 4/4/2011


  1. Overview of Mitochondrial Diseases. NAMDC. Accessed 4/3/2011.
  2. Cassandra L. Kniffin. MITOCHONDRIAL COMPLEX III DEFICIENCY. OMIM. November 29, 2010; Accessed 4/3/2011.
  3. Treatments & Therapies. United Mitochondrial Disease Foundation. Accessed 4/3/2011.
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In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Mitochondrial complex III deficiency. Click on the link to view a sample search on this topic.