06/02/2015 11:30 PM EDT
Source: National Library of Medicine
Related MedlinePlus Page: Metabolic Disorders
Related MedlinePlus Page: Metabolic Disorders
Multiple mitochondrial dysfunctions syndrome
What is multiple mitochondrial dysfunctions syndrome?
Multiple mitochondrial dysfunctions syndrome is characterized by impairment of cellular structures called mitochondria, which are the energy-producing centers of cells. While certain mitochondrial disorders are caused by impairment of a single stage of energy production, individuals with multiple mitochondrial dysfunctions syndrome have reduced function of more than one stage. The signs and symptoms of this severe condition begin early in life, and affected individuals usually do not live past infancy.
Affected infants typically have severe brain dysfunction (encephalopathy), which can contribute to weak muscle tone (hypotonia), seizures, and delayed development of mental and movement abilities (psychomotor delay). These infants often have difficulty growing and gaining weight at the expected rate (failure to thrive). Most affected babies have a buildup of a chemical called lactic acid in the body (lactic acidosis), which can be life-threatening. They may also have high levels of a molecule called glycine (hyperglycinemia) or elevated levels of sugar (hyperglycemia) in the blood. Some babies with multiple mitochondrial dysfunctions syndrome have high blood pressure in the blood vessels that connect to the lungs (pulmonary hypertension) or weakening of the heart muscle (cardiomyopathy).
How common is multiple mitochondrial dysfunctions syndrome?
Multiple mitochondrial dysfunctions syndrome is a rare condition; its prevalence is unknown. It is one of several conditions classified as mitochondrial disorders, which affect an estimated 1 in 5,000 people worldwide.
What genes are related to multiple mitochondrial dysfunctions syndrome?
Multiple mitochondrial dysfunctions syndrome can be caused by mutations in the NFU1 or BOLA3gene. The proteins produced from each of these genes appear to be involved in the formation of molecules called iron-sulfur (Fe-S) clusters or in the attachment of these clusters to other proteins. Certain proteins require attachment of Fe-S clusters to function properly.
The NFU-1 and BOLA3 proteins play an important role in mitochondria. In these structures, several proteins carry out a series of chemical steps to convert the energy in food into a form that cells can use. Many of the proteins involved in these steps require Fe-S clusters to function, including protein complexes called complex I, complex II, and complex III.
Fe-S clusters are also required for another mitochondrial protein to function; this protein is involved in the modification of additional proteins that aid in energy production in mitochondria, including the pyruvate dehydrogenase complex and the alpha-ketoglutarate dehydrogenase complex (also known as the oxoglutarate dehydrogenase complex). This modification is also critical to the function of the glycine cleavage system, a set of proteins that breaks down a protein building block (amino acid) called glycine when levels become too high.
Mutations in the NFU1 or BOLA3 gene reduce or eliminate production of the respective protein, which impairs Fe-S cluster formation. Consequently, proteins affected by the presence of Fe-S clusters, including those involved in energy production and glycine breakdown, cannot function normally. Reduced activity of complex I, II, or III, pyruvate dehydrogenase, or alpha-ketoglutarate dehydrogenase leads to potentially fatal lactic acidosis, encephalopathy, and other signs and symptoms of multiple mitochondrial dysfunctions syndrome. In some affected individuals, impairment of the glycine cleavage system leads to a buildup of glycine.
How do people inherit multiple mitochondrial dysfunctions syndrome?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Where can I find information about diagnosis or management of multiple mitochondrial dysfunctions syndrome?
These resources address the diagnosis or management of multiple mitochondrial dysfunctions syndrome and may include treatment providers.
- Gene Review: Mitochondrial Disorders
Overview - Genetic Testing Registry: Multiple mitochondrial dysfunctions syndrome
1 - Genetic Testing Registry: Multiple mitochondrial dysfunctions syndrome
2 - Genetic Testing Registry: Multiple mitochondrial dysfunctions syndrome
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You might also find information on the diagnosis or management of multiple mitochondrial dysfunctions syndrome in Educational resources and Patient support.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about multiple mitochondrial dysfunctions syndrome?
You may find the following resources about multiple mitochondrial dysfunctions syndrome helpful. These materials are written for the general public.
- MedlinePlus - Health information (2 links)
- Additional NIH Resources - National Institutes of Health (2 links)
- Educational resources - Information pages (5 links)
- Patient support - For patients and families (2 links)
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
- Gene
Reviews - Clinical summary - Genetic Testing Registry - Repository of genetic test information (3 links)
ClinicalTrials.gov - Linking patients to medical researchPubMed - Recent literature- OMIM - Genetic disorder catalog (3 links)
What other names do people use for multiple mitochondrial dysfunctions syndrome?
- MMDS
- multiple mitochondrial dysfunction syndrome
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines and How are genetic conditions and genes named? in the Handbook.
What if I still have specific questions about multiple mitochondrial dysfunctions syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
- What does it mean if a disorder seems to run in my family?
- What are the different ways in which a genetic condition can be inherited?
- If a genetic disorder runs in my family, what are the chances that my children will have the condition?
- Why are some genetic conditions more common in particular ethnic groups?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding multiple mitochondrial dysfunctions syndrome?
acidosis ; amino acid ; autosomal ; autosomal recessive ; breakdown ; cardiomyopathy ; cell ;dehydrogenase ; encephalopathy ; failure to thrive ; gene ; glycine ; hyperglycemia ; hypertension ;hypotonia ; inherited ; iron ; lactic acid ; lactic acidosis ; mitochondria ; molecule ; muscle tone ;prevalence ; protein ; psychomotor ; pulmonary ; recessive ; stage ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (4 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook
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