Mitochondrial complex I deficiency
Last updated 18 Aug 2020
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Mitochondrial complex I deficiency is a shortage (deficiency) of a protein complex called complex I or a loss of its function. Complex I is found in cell structures called mitochondria, which convert the energy from food into a form that cells can use. Complex I is the first of five mitochondrial complexes that carry out a multi-step process called oxidative phosphorylation, through which cells derive much of their energy.
Description
Mitochondrial complex I deficiency is a shortage (deficiency) of a protein complex called complex I or a loss of its function. Complex I is found in cell structures called mitochondria, which convert the energy from food into a form that cells can use. Complex I is the first of five mitochondrial complexes that carry out a multi-step process called oxidative phosphorylation, through which cells derive much of their energy.
Mitochondrial complex I deficiency can cause a wide variety of signs and symptoms affecting many organs and systems of the body, particularly the nervous system, the heart, and the muscles used for movement (skeletal muscles). These signs and symptoms can appear at any time from birth to adulthood.
People with mitochondrial complex I deficiency typically have neurological problems, such as abnormal brain function (encephalopathy), recurrent seizures (epilepsy), intellectual disability, difficulty coordinating movements (ataxia), or involuntary movements (dystonia). Affected individuals may have low muscle tone (hypotonia), muscle pain (myalgia), and extreme fatigue in response to physical activity (exercise intolerance). They tend to develop elevated levels of lactic acid in the blood (lactic acidosis), which can cause nausea, vomiting, weakness, and rapid breathing. In severe cases, lactic acidosis can be life-threatening.
People with mitochondrial complex I deficiency sometimes have heart, liver, or kidney problems. Vision problems due to abnormal eye movement or breakdown (degeneration) of the nerves that carry signals from the eyes to the brain (optic nerves) can also occur.
Some people with mitochondrial complex I deficiency have groups of signs and symptoms that are classified as a specific syndrome. For example, a condition called Leigh syndrome is most commonly caused by mitochondrial complex I deficiency. Leigh syndrome is characterised by progressive loss of mental and movement abilities (developmental or psychomotor regression) and typically results in death within 2 to 3 years from the onset of symptoms. Another condition that can be caused by mitochondrial complex I deficiency, Leber hereditary optic neuropathy, is associated mainly with vision problems due to optic nerve degeneration. These syndromes can also have other causes.
Inheritance patterns
The source lists the following possible inheritance patterns: X-linked; mitochondrial; Autosomal recessive. More than one pattern can apply in different cases.
Related genes
Other names
NADH-coenzyme Q reductase deficiency
NADH:Q(1) oxidoreductase deficiency
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Further reading and references
- Mitochondrial complex I deficiency; MedlinePlus, National Library of Medicine.
- Alston CL, Rocha MC, Lax NZ, Turnbull DM, Taylor RW. The genetics and pathology of mitochondrial disease. J Pathol. 2017 Jan;241(2):236-250. doi: 10.1002/path.4809. Epub 2016 Nov 2.
- Blanchet L, Buydens MC, Smeitink JA, Willems PH, Koopman WJ. Isolated mitochondrial complex I deficiency: explorative data analysis of patient cell parameters. Curr Pharm Des. 2011 Dec 1;17(36):4023-33. doi: 10.2174/138161211798764870.
- Distelmaier F, Koopman WJ, van den Heuvel LP, Rodenburg RJ, Mayatepek E, Willems PH, Smeitink JA. Mitochondrial complex I deficiency: from organelle dysfunction to clinical disease. Brain. 2009 Apr;132(Pt 4):833-42. doi: 10.1093/brain/awp058. Epub 2009 Mar 31.
- Fernandez-Vizarra E, Tiranti V, Zeviani M. Assembly of the oxidative phosphorylation system in humans: what we have learned by studying its defects. Biochim Biophys Acta. 2009 Jan;1793(1):200-11. doi: 10.1016/j.bbamcr.2008.05.028. Epub 2008 Jun 21.
- Leman G, Gueguen N, Desquiret-Dumas V, Kane MS, Wettervald C, Chupin S, Chevrollier A, Lebre AS, Bonnefont JP, Barth M, Amati-Bonneau P, Verny C, Henrion D, Bonneau D, Reynier P, Procaccio V. Assembly defects induce oxidative stress in inherited mitochondrial complex I deficiency. Int J Biochem Cell Biol. 2015 Aug;65:91-103. doi: 10.1016/j.biocel.2015.05.017. Epub 2015 May 27.
- Pagniez-Mammeri H, Loublier S, Legrand A, Benit P, Rustin P, Slama A. Mitochondrial complex I deficiency of nuclear origin I. Structural genes. Mol Genet Metab. 2012 Feb;105(2):163-72. doi: 10.1016/j.ymgme.2011.11.188. Epub 2011 Nov 18.
- Pagniez-Mammeri H, Rak M, Legrand A, Benit P, Rustin P, Slama A. Mitochondrial complex I deficiency of nuclear origin II. Non-structural genes. Mol Genet Metab. 2012 Feb;105(2):173-9. doi: 10.1016/j.ymgme.2011.10.001. Epub 2011 Oct 20.
- Vartak RS, Semwal MK, Bai Y. An update on complex I assembly: the assembly of players. J Bioenerg Biomembr. 2014 Aug;46(4):323-8. doi: 10.1007/s10863-014-9564-x. Epub 2014 Jul 17.
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