Neuropathy, ataxia, and retinitis pigmentosa

Neuropathy, ataxia, and retinitis pigmentosa
Classification and external resources
ICD-9	277.87
OMIM	551500
DiseasesDB	34335

Neuropathy, ataxia, and retinitis pigmentosa (NARP) is a condition that causes a variety of signs and symptoms chiefly affecting the nervous system. Beginning in childhood or early adulthood, most people with NARP experience numbness, tingling, or pain in the arms and legs (sensory neuropathy); muscle weakness; and problems with balance and coordination (ataxia). Many affected individuals also have vision loss caused by changes in the light-sensitive tissue that lines the back of the eye (the retina). In some cases, the vision loss results from a condition called retinitis pigmentosa. This eye disease causes the light-sensing cells of the retina gradually to deteriorate.

Learning disabilities and developmental delays are often seen in children with NARP, and older individuals with this condition may experience a loss of intellectual function (dementia). Other features of NARP include seizures, hearing loss, and abnormalities of the electrical signals that control the heartbeat (cardiac conduction defects). These signs and symptoms vary among affected individuals.

Neuropathy, ataxia, and retinitis pigmentosa is a condition related to changes in mitochondrial DNA. Mutations in the MT-ATP6 gene cause neuropathy, ataxia, and retinitis pigmentosa. The MT-ATP6 gene provides instructions for making a protein that is essential for normal mitochondrial function. Through a series of chemical reactions, mitochondria use oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source. The MT-ATP6 protein forms one part (subunit) of an enzyme called ATP synthase, which is responsible for the last step in ATP production. Mutations in the MT-ATP6 gene alter the structure or function of ATP synthase, reducing the ability of mitochondria to make ATP. It remains unclear how this disruption in mitochondrial energy production leads to muscle weakness, vision loss, and the other specific features of NARP.

This condition is inherited in a pattern reflecting its location in mitochondrial DNA, which is also known as maternal inheritance. This pattern of inheritance applies to genes contained in mitochondrial DNA. Because egg cells, but not sperm cells, contribute mitochondria to the developing embryo, only females pass mitochondrial conditions to their children. Mitochondrial disorders can appear in every generation of a family and can affect both males and females, but fathers do not pass mitochondrial traits to their children. Most of the body's cells contain thousands of mitochondria, each with one or more copies of mitochondrial DNA. The severity of some mitochondrial disorders is associated with the percentage of mitochondria in each cell that has a particular genetic change. Most individuals with NARP have a specific MT-ATP6 mutation in 70 percent to 90 percent of their mitochondria. When this mutation is present in a higher percentage of a person's mitochondria—greater than 90 percent to 95 percent—it causes a more severe condition known as maternally inherited Leigh syndrome. Because these two conditions result from the same genetic changes and can occur in different members of a single family, researchers believe that they may represent a spectrum of overlapping features instead of two distinct syndromes.

References

• Neuropathy, ataxia, and retinitis pigmentosa at NLM Genetics Home Reference

This article about a disease of the nervous system is a stub. You can help Wikipedia by expanding it.v · Categories: Mitochondrial diseases Disease stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать реферат XPTO Red Sea Trading Corporation Look at other dictionaries: Neuropathy (disambiguation) — Neuropathy usually refers to peripheral neuropathy, which denotes damage to nerves of the peripheral nervous system. Neuropathy may also refer to: Cranial neuropathy, any condition affecting cranial nerves Auditory neuropathy, any condition… …   Wikipedia NARP — Neuropathy Ataxia And Retinitis Pigmentosa (Community » Non Profit Organizations) National Association of Registered Petsitters (Medical » Veterinary) …   Abbreviations dictionary NARP — stands for Neuropathy, Ataxia and Retinitis Pigmentosa. NARP is a disease featuring weakness of the muscles near the trunk, ataxia (wobbliness), retinal disease, seizures and developmental delay. NARP is a mitochondrial disease in that it is due… …   Medical dictionary One and a half syndrome — Schematic representation of most common extra ocular movement abnormality in one and a half syndrome. The one and a half syndrome is a rare ophthalmoparetic syndrome characterized by a conjugate horizontal gaze palsy in one direction and an… …   Wikipedia Optic neuropathy — Classification and external resources ICD 10 H46 The optic nerve contains axons of nerve cells that emerge from the retina, leave the eye at the optic disc, and go to the visual cortex where input from the eye is processed into vision. There are… …   Wikipedia DNA, mitochondrial — Mitochondrial DNA (mtDNA) is the DNA of the mitochondrion, a structure situated in the cytoplasm of the cell rather than in the nucleus (where all the other chromosomes are located). All mtDNA is inherited from the mother. There are 2 to 10… …   Medical dictionary Mitochondrial DNA — (mtDNA) is the DNA of the mitochondrion, a structure situated in the cytoplasm of the cell rather than in the nucleus (where all the other chromosomes are located). All mtDNA is inherited from the mother. There are 2 to 10 copies of the mtDNA… …   Medical dictionary mtDNA — Mitochondrial DNA (mtDNA) is the DNA of the mitochondrion, a structure situated in the cytoplasm of the cell rather than in the nucleus (where all the other chromosomes are located). All mtDNA is inherited from the mother. There are 2 to 10… …   Medical dictionary NARP — may refer to: The genetic disorder Neuropathy, ataxia, and retinitis pigmentosa The National Association of Railroad Passengers No apparent reason party, a term to describe a celebratory gathering without any specific purpose. North American… …   Wikipedia MT-ATP6 — protein Name=mitochondrially encoded ATP synthase 6 caption= width= HGNCid=7414 Symbol=MT ATP6 AltSymbols=MTATP6 EntrezGene=4508 OMIM=516060 RefSeq= UniProt=Q4VGD2 PDB= ECnumber=3.6.3.14 Chromosome=MT Arm= Band= LocusSupplementaryData=MT ATP6 is… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”