Spinocerebellar ataxia
2304494
217337625
2008-06-05T16:21:49Z
Edward
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link [[sleep disorder]]
{{Infobox_Disease |
Name = {{PAGENAME}} |
Image = brain-cerebellum.png |
Caption = Cerebellum (in blue) of the human brain |
DiseasesDB = 12339 |
ICD10 = {{ICD10|G|11||g|10}} |
ICD9 = {{ICD9|334}} |
ICDO = |
OMIM = |
MedlinePlus = |
eMedicineSubj = |
eMedicineTopic = |
MeshID = D020754 |
}}
'''Spinocerebellar ataxia''' ('''SCA''') is a genetic [[disease]] with multiple types, each of which could be considered a disease in its own right.
==Symptoms==
Spinocerebellar ataxia (SCA) is one of a group of [[genetic disorder]]s characterized by slowly progressive incoordination of [[Gait (human)|gait]] and often associated with poor coordination of hands, speech, and eye movements. Frequently, [[atrophy]] of the [[cerebellum]] occurs. <ref>[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=gnd.section.218 Genes and Disease at nlm.nih.gov] - Gives a concise description of SCA, along with a picture of shrunken degenerated cerebellum.</ref>
As with other forms of [[ataxia]], SCA results in unsteady and clumsy motion of the body due to a failure of the fine coordination of [[muscle]] movements, along with other [[symptom]]s.
The symptoms of the condition vary with the specific type (there are several), and with the individual patient. Generally, a person with ataxia retains full mental capacity but may progressively lose physical control.
==Treatment and prognosis==
There is no known cure for spinocerebellar ataxia, which is a progressive disease (it gets worse with time), although not all types cause equally severe disability.
Treatments are generally limited to softening symptoms, not the disease itself. The condition can be irreversible. A person with this disease will usually end up needing to use a [[wheelchair]], and eventually they may need assistance to perform daily tasks.
The treatment of incoordination or ataxia, then mostly involves the use of adaptive devices to allow the ataxia individual to maintain as much independence as possible. Such devices may include a cane, crutches, walker, or wheelchair for those with impaired gait; devices to assist with writing, feeding, and self care if hand and arm coordination are impaired; and communication devices for those with impaired speech.
Many patients with hereditary or idiopathic forms of ataxia have other symptoms in addition to ataxia. Medications or other therapies might be appropriate for some of these symptoms, which could include tremor, stiffness, depression, spasticity, and [[sleep disorder]]s, among others.
Both onset of initial symptoms and duration of disease can be subject to variation. If the disease is caused by a polyglutamine [[trinucleotide repeat]] CAG expansion, a longer expansion may lead to an earlier onset and a more radical progression of clinical symptoms.
==Diagnosis==
It can be easily misdiagnosed as another [[neurology|neurological]] condition, such as [[multiple sclerosis]] (MS).
One means of identifying the disease is with an [[magnetic resonance imaging|MRI]] to view the brain. Once the disease has progressed sufficiently, the [[cerebellum]] (a part of the [[brain]]) can be seen to have visibly shrunk. The most precise means of identifying SCA, including the specific type, is through [[DNA]] analysis. Some, but far from all, types of SCA may be inherited, so a DNA test may be done on the children of a sufferer, to see if they are at risk of developing the condition.
SCA is related to [[olivopontocerebellar atrophy]] (OPCA); SCA types 1, 2, and 7 are also types of OPCA. However, not all types of OPCA are types of SCA, and vice versa. This overlapping classification system is both confusing and controversial to some in this field.
==Types==
The following is a list of some, not all, types of ''Spinocerebellar ataxia''.
The first ataxia [[gene]] was identified in [[1993]] for a dominantly inherited type. It was called “Spinocerebellar ataxia type 1" (SCA1). Subsequently, as additional dominant genes were found they were called SCA2, SCA3, etc. Usually, the "type" number of "SCA" refers to the order in which the gene was found. At this time, there are at least 29 different gene mutations which have been found (not all listed).
Identifying the different types of SCA now requires knowledge of the normal genetic code, and faults in this code, which are contained in a person's [[DNA]] (Deoxyribonucleic acid). The "CAG" mentioned below is one of many three-letter sequences that makes up the genetic code, this specific one coding the amino acid glutamine. Thus, those ataxias with poly CAG expansions, along with several other neurodegenerative diseases resulting from a poly CAG expansion, are referred to as [[polyglutamine disease]]s.
{| class="wikitable"
!SCA Type
!Average Onset<br>(Range in Years)
!Average Duration<br>(Range in Years)
!What the patient experiences
!Common origin
!Problems<br>with [[DNA]]
|-
|SCA1<ref>{{GeneTests|sca1}}</ref> ([[ATXN1]])
|4th decade<br>(<10 to >60)
|15 years<br>(10-28)
|Hypermetric [[saccades]], slow saccades, [[upper motor neuron]]<br>(note: saccades relates to eye movement)
|
|CAG [[Repeated sequence (DNA)|repeat]], 6p ([[Ataxin 1]])
|-
|SCA2<ref>{{GeneTests|sca2}}</ref> ([[ATXN2]])
|3rd - 4th decade<br>(<10 to >60)
|10 years<br>(1-30)
|Diminished velocity saccades<br>'''areflexia''' (absence of [[neurologic]] [[reflexes]])
|[[Cuba]]
|CAG [[Repeated sequence (DNA)|repeat]], 12q
|-
|SCA3<ref>{{GeneTests|sca3}}</ref> (MJD) ([[ATXN3]])
|4th decade<br>(10-70)
|10 years<br>(1-20)
|Also called [[Machado-Joseph disease]] (MJD)<ref>{{NINDS|machado_joseph}}</ref><br>Gaze-evoked [[nystagmus]] (a rapid, involuntary, [[oscillation|oscillatory]] [[motion (physics)| motion]] of the eyeball)<br>[[upper motor neuron]]<br>slow saccades
|[[Azores]]<br>([[Portugal]])
|CAG [[Repeated sequence (DNA)|repeat]], 14q
|-
|SCA4 ([[PLEKHG4]])
|4th - 7th decade<br>(19-72)
|Decades
|'''areflexia''' (absence of [[neurologic]] [[reflexes]])
|
|[[Chromosome]] 16q
|-
|SCA5 ([[SPTBN2]])
|3rd - 4th decade<br>(10-68)
|>25 years
|Pure [[Cerebellum|cerebellar]]
|
|[[Chromosome]] 11
|-
|[[Spinocerebellar ataxia type-6|SCA6]]<ref>{{GeneTests|sca6}}</ref> ([[CACNA1A]])
|5th - 6th decade<br>(19-71)
|>25 years
|Downbeating [[nystagmus]], positional [[Vertigo_(medical)|vertigo]]<br>[[Symptoms]] can appear for the first time as late as 65 years old.
|
|CAG [[Repeated sequence (DNA)|repeat]], 19p<br>[[Calcium]] channel [[gene]]
|-
|SCA7<ref>{{GeneTests|sca7}}</ref> ([[ATXN7]])
|3rd - 4th decade<br>(0.5 - 60)
|20 years<br>(1-45; early onset correlates with shorter duration)
|[[Macular degeneration]], [[upper motor neuron]], slow saccades
|
|CAG [[Repeated sequence (DNA)|repeat]], 3p ([[Ataxin 7]])
|-
|SCA8<ref>{{GeneTests|sca8}}</ref> ([[IOSCA]])
|39 yrs<br>(18-65)
|Normal lifespan
|[[Horizontal]] [[nystagmus]] (a rapid, involuntary, [[oscillation|oscillatory]] motion of the [[eyeball]])
|
|CTG [[Repeated sequence (DNA)|repeat]], 13q
|-
|SCA10<ref>{{GeneTests|sca10}}</ref> ([[ATXN10]])
|36 years
|9 years
|[[ataxia]], [[seizure]]s
|[[Mexico]]
|[[Chromosome]] 22q linked<br>pentanucleotide [[Repeated sequence (DNA)|repeat]]
|-
|[[SCA11]]
|30 yrs<br>(15-70)
|Normal lifespan
|Mild, remain [[Wiktionary:ambulatory|ambulatory]] (able to walk about on one's own)
|
|15q
|-
|SCA12<ref>{{GeneTests|sca12}}</ref> ([[PPP2R2B]])
|33 yrs<br>(8-55)
|
|[[Head]] and [[hand]] [[tremor]],<br>[[akinesia]] (loss of normal motor function, resulting in impaired [[muscle]] movement)
|
|CAG [[Repeated sequence (DNA)|repeat]], 5q
|-
|[[Spinocerebellar ataxia type-13|SCA13]]
|Childhood or adulthood depending on mutation
|Depending on [[KCNC3]] (a kind of gene)
|[[Mental retardation]]
|
|19q
|-
|SCA14<ref>{{GeneTests|sca14}}</ref> ([[PRKCG]])
|28 yrs<br>(12-42)
|Decades<br>(1-30)
|[[Myoclonus]] (a sudden [[muscle contraction|twitching]] of [[muscle]]s or parts of muscles, without any rhythm or pattern, occurring in various [[brain]] disorders)
|
|19q
|-
|[[SCA16]]
|39 yrs<br>(20-66)
|1-40 years
|[[Head]] and [[hand]] [[tremor]]
|
|8q
|-
|SCA17 ([[TATA binding protein|TBP]])
|
|
|
|
|CAG [[Repeated sequence (DNA)|repeat]], 6q (TATA-binding protein)
|-
|[[SCA19]], [[SCA22]]
|
|
|Mild [[cerebellum|cerebellar]] [[syndrome]], [[dysarthria]]
|
|
|-
|[[SCA25]]
|1.5-39 yrs
|Unknown
|[[ataxia]] with [[sense|sensory]] [[neuropathy]], [[vomiting]] and [[gastrointestinal tract|gastrointestinal]] [[pain]].
|
|2p
|}
Others include [[SCA18]], [[SCA20]], [[SCA21]], [[SCA23]], [[SCA26]], [[SCA28]], and [[SCA29]].
Four X-linked types have been described ({{OMIM2|302500}}, {{OMIM2|302600}}, {{OMIM2|301790}}, {{OMIM2|301840}}), but only the first of these has so far been tied to a gene ([[SCAX1]]).
==Inheritance==
The [[heredity|hereditary]] ataxias are categorized by mode of inheritance and causative [[gene]] or [[chromosome|chromosomal]] locus. The hereditary ataxias can be inherited in an [[autosomal dominant]], [[autosomal recessive]], or [[X-linked manner]].
* Numerous types of ''autosomal dominant'' cerebellar ataxias are now known for which specific genetic information is available. Synonyms for autosomal dominant cerebellar ataxias (ADCA) used prior to the current understanding of the molecular genetics were Marie's ataxia, inherited olivopontocerebellar atrophy, cerebello-olivary atrophy, or the more generic term "spinocerebellar degeneration." ('''Spinocerebellar degeneration''' is a rare inherited neurological disorder of the [[central nervous system]] characterized by the slow degeneration of certain areas of the brain. There are three forms of spinocerebellar degeneration: Types 1, 2, 3. Symptoms begin during adulthood.)
* There are five typical ''autosomal recessive'' disorders in which ataxia is a prominent feature: [[Friedreich ataxia]], [[ataxia-telangiectasia]], ataxia with vitamin E deficiency, ataxia with oculomotor apraxia (AOA), [[spastic ataxia]]. Disorder Subdivisions: Friedreich's ataxia, Spinocerebellar ataxia, Ataxia telangiectasia, Vasomotor ataxia, Vestibulocerebellar, Ataxiadynamia, Ataxiophemia, Olivopontocerebellar atrophy, and [[Charcot-Marie-Tooth disease]].
<gallery>
Image:Autodominant.jpg|There are numerous types of [[autosomal dominant]] cerebellar ataxias
Image:autorecessive.jpg|There are five typical [[Recessive gene|autosomal recessive]] disorders in which ataxia is a prominent feature
</gallery>
==Notable cases==
Sufferers from the disease include:
* [[Glyn Worsnip]] (2 September 1938 - 7 June 1996), British television presenter.
* [[Aya Kitō]] (19 July 1962 - 23 May 1988), a Japanese girl who wrote a diary about her experience with the disease. Her diary, titled '[[1 Litre no Namida|1 Litre of Tears]]' was published after her death and adopted into a [[television drama]] of the ''[[1 Litre no Namida (TV series)|1 Litre no Namida]]'' and the film ''[[A Litre of Tears (film)|A Litre of Tears]]''.
* The [[Ulas family]] featured in the 2006 BBC and NOVA documentary, ''[[The Family That Walks On All Fours]]'' have nonprogressive congential cerebellar ataxia that led them to walk with a [[quadrupedal]] gait.
==References==
<references/>
==External links==
*http://www.ataxia.org - National Ataxia Foundation is dedicated to helping families with ataxia through research, education, and support.
*[http://www.tchain.com/otoneurology/disorders/central/cerebellar/sca.htm Cerebellar Degenerations at tchain.com]
* http://leedsdna.info/tests/DRPLA.htm
* http://www.ataxiaforums.co.uk
*[http://wiki.d-addicts.com/Ichi_Rittoru_no_Namida Ichi Rittoru no Namida (One Litre of Tears)] - A Japanese drama based on the true story of a girl who suffered from Spinocerebellar ataxia.
*[http://www.cureataxia.org CureAtaxia.org] - One Chicago family's fight against SCA Type 1 Ataxia
{{Diseases of the nervous system}}
[[Category:Disability]]
[[Category:Genetic_disorders]]
[[Category:Neurological disorders]]
[[de:Spinozerebelläre Ataxie]]
[[fr:Ataxie spinocérébelleuse]]
[[it:Atassia spinocerebellare]]
[[ja:脊髄小脳変性症]]
[[pl:Ataksja rdzeniowo-móżdżkowa]]
[[th:สไปโนซีรีเบลลาร์อะแท็กเซีย]]
[[zh:小腦萎縮症]]