- Spinocerebellar ataxia
Spinocerebellar ataxia (SCA) is a genetic
diseasewith multiple types, each of which could be considered a disease in its own right.
Spinocerebellar ataxia (SCA) is one of a group of
genetic disorders characterized by slowly progressive incoordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophyof the cerebellumoccurs. [ [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.]
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 musclemovements, along with other symptoms.
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 ataxic 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 disorders, 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 repeatCAG expansion, a longer expansion may lead to an earlier onset and a more radical progression of clinical symptoms.
It can be easily misdiagnosed as another neurological condition, such as
One means of identifying the disease is with an 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 DNAanalysis. 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.
The following is a list of some, not all, types of "Spinocerebellar ataxia". The first ataxia
genewas identified in 1993for 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 diseases.
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 (
The hereditary ataxias are categorized by mode of inheritance and causative
geneor 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 systemcharacterized 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.
Sufferers from the disease include:
Glyn Worsnip(2 September 1938 - 7 June 1996), British television presenter.
Aya Kitō(19 July 1992 - 23 May 1988), a Japanese girl who wrote a diary about her experience with the disease. Her diary, titled '1 Litre of Tears' was published after her death and adopted into a television dramaof the "1 Litre no Namida" and the film "A Litre of Tears".
Ulas familyfeatured 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 quadrupedalgait.
*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://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
*OMIM3|183090 RareDiseases|4071|Spinocerebellar ataxia 1
*OMIM3|164400 RareDiseases|4072|Spinocerebellar ataxia 2
*OMIM3|607317 RareDiseases|4952|Spinocerebellar ataxia, autosomal recessive 4
*OMIM3|600224 RareDiseases|4953|Spinocerebellar ataxia 5
*OMIM3|605259 RareDiseases|9611|Spinocerebellar ataxia 13
*OMIM3|117360 RareDiseases|9975|Spinocerebellar ataxia 30
*OMIM3|608703 RareDiseases|9996|Spinocerebellar ataxia 25
*OMIM3|600223 RareDiseases|9970|Spinocerebellar ataxia 4
*OMIM3|606002 RareDiseases|4949|Spinocerebellar ataxia, autosomal recessive 1
*OMIM3|271250 RareDiseases|9971|Spinocerebellar ataxia, autosomal recessive 3
*OMIM3|609306 RareDiseases|9995|Spinocerebellar ataxia 26
*OMIM3|608029 RareDiseases|4954|Spinocerebellar ataxia, autosomal recessive 6
*OMIM3|607346 RareDiseases|9969|Spinocerebellar ataxia 19
*OMIM3|608687 RareDiseases|9997|Spinocerebellar ataxia 20
*OMIM3|302600 RareDiseases|9978|Spinocerebellar ataxia, X-linked, 2
*OMIM3|606937 RareDiseases|9977|Spinocerebellar ataxia, autosomal recessive 5
*OMIM3|301840 RareDiseases|9980|Spinocerebellar ataxia, X-linked, 4
*OMIM3|301790 RareDiseases|9981|Spinocerebellar ataxia, X-linked, 3
*OMIM3|109150 RareDiseases|6801|Spinocerebellar ataxia 3; Machado Joseph disease
*OMIM3|607458 RareDiseases|9976|Spinocerebellar ataxia 18
*RareDiseases|9963|Spinocerebellar ataxia 27
*OMIM3|164500 RareDiseases|4955|Spinocerebellar ataxia 7
*OMIM3|607454 RareDiseases|9999|Spinocerebellar ataxia 99
*OMIM3|610245 RareDiseases|9950|Spinocerebellar ataxia 23
*OMIM3|610246 RareDiseases|9951|Spinocerebellar ataxia 28
*OMIM3|603680 RareDiseases|4956|Spinocerebellar ataxia 8
*OMIM3|607250 RareDiseases|10000|Spinocerebellar ataxia, autosomal recessive, with axonal neuropathy
*OMIM3|605361 RareDiseases|4062|Infantile onset Spinocerebellar ataxia
*OMIM3|271245 RareDiseases|4957|Spinocerebellar ataxia amyotrophy deafness
*RareDiseases|4958|Spinocerebellar ataxia dysmorphism
*OMIM3|301310 RareDiseases|668|Anemia, sideroblastic spinocerebellar ataxia; Pagon Bird Detter syndrome
*OMIM3|229300 RareDiseases|6468|Friedreich's ataxia; Spinocerebellar ataxia, Friedreich
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