Maternally Inherited Leigh Syndrome and NARP Syndrome
National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Maternally Inherited Leigh Syndrome and NARP Syndrome is not the name you expected.
Maternally inherited Leigh syndrome (MILS) and neuropathy, ataxia and retinitis pigmentosa (NARP) syndrome are rare genetic multisystem disorders that are part of a spectrum or continuum of disease caused by abnormalities affecting mitochondrial energy production. NARP is characterized by nerve disease affecting the nerves outside of the central nervous system (peripheral neuropathy), an impaired ability to coordinate voluntary movements (ataxia), an eye condition known as retinitis pigmentosa (RP), and a variety of additional abnormalities. MILS is generally a more severe mitochondrial disorder that often becomes apparent during infancy or childhood and is characterized by brain disease (encephalopathy), elevated levels of lactic acid in the body (lactic acidosis), seizures, heart disease (cardiomyopathy), breathing (respiratory) abnormalities, and developmental delays. The specific symptoms and severity of these disorders in each individual can vary greatly from one person to another and even among members of the same family.
MILS and NARP syndrome are maternally inherited mitochondrial disorders. They are caused by specific mutations affecting the mitochondrial gene known as the ATPase 6 gene. When individuals have more than 90 percent of mutated mitochondrial DNA (mtDNA) in their cells, they are classified as having MILS and not NARP syndrome. Most individuals with NARP syndrome have 70-80 percent of mutated mtDNA. In some families, one individual may have NARP syndrome while another individual is diagnosed with MILS. (For more information on mtDNA see the Causes section below.)
Mitochondrial disorders are characterized by mutations affecting the parts of the cell that release energy (mitochondria). Mitochondrial diseases often hamper the ability of affected cells to break down food and oxygen and produce energy. In most mitochondrial disorders, abnormally high numbers of defective mitochondria are present in the cells of the body. Mitochondrial diseases often affect more than one organ system of the body. NARP syndrome was first identified in the medical literature in 1990. Leigh syndrome was first reported in the medical literature in 1951.
CLIMB (Children Living with Inherited Metabolic Diseases)
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Children's Mitochondrial Disease Network
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Genetic and Rare Diseases (GARD) Information Center
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Mitochondria Research Society
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Mitochondrial Medicine Society
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NIH/National Institute of Neurological Disorders and Stroke
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Retinitis Pigmentosa International
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United Mitochondrial Disease Foundation
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For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
Last Updated: 3/22/2016
Copyright 2013 National Organization for Rare Disorders, Inc.
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