Neuropathy, Ataxia and Retinitis Pigmentosa
National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Neuropathy, Ataxia and Retinitis Pigmentosa is not the name you expected.
Neuropathy, ataxia and retinitis pigmentosa (NARP) syndrome is a rare genetic disorder. It 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. RP is a general term for a group of vision disorders that cause progressive degeneration of the membrane lining the eyes (retina) resulting in visual impairment. The specific symptoms of NARP syndrome in each individual vary greatly from case to case. The disorder is a maternally inherited mitochondrial disease.
NARP syndrome belongs to a group disorders known as mitochondrial disorders. These 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 is caused by a specific mutation affecting the mitochondrial gene known as the ATPase 6 gene. This mutation can also cause a specific subtype of Leigh's syndrome known as maternally inherited Leigh's syndrome (MILS). In fact, 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. (For more information on Leigh's disease, see the Related Disorders section of this report.)
United Mitochondrial Disease Foundation
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This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to MyD-H, the Dartmouth-Hitchcock patient portal. You must be a registered MyD-H user for the Lebanon, Manchester, or Nashua locations to access this site.
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Last Updated: 11/30/2005
Copyright 2005 National Organization for Rare Disorders, Inc.
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