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Spinocerebellar ataxia
ICD-10 G11
ICD-9 334
OMIM [1]
DiseasesDB 12339
MedlinePlus [2]
eMedicine /
MeSH {{{MeshNumber}}}

Spinocerebellar ataxia (SCA) is a genetic disease with multiple types, each of which could be considered a disease in its own right.





Treatment and prognosis[]









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 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 diseases.

SCA Type Average Onset
(Range in Years)
Average Duration
(Range in Years)
What the patient experiences Common origin Problems
with DNA
SCA1[2] (ATXN1) 4th decade
(<10 to >60)
15 years
Hypermetric saccades, slow saccades, upper motor neuron
(note: saccades relates to eye movement)
  CAG repeat, 6p (Ataxin 1)
SCA2[3] (ATXN2) 3rd - 4th decade
(<10 to >60)
10 years
Diminished velocity saccades
areflexia (absence of neurologic reflexes)
Cuba CAG repeat, 12q
SCA3[4] (MJD) (ATXN3) 4th decade
10 years
Also called Machado-Joseph disease (MJD)[5]
Gaze-evoked nystagmus (a rapid, involuntary, oscillatory motion of the eyeball)
upper motor neuron
slow saccades
CAG repeat, 14q
SCA4 (PLEKHG4) 4th - 7th decade
Decades areflexia (absence of neurologic reflexes)   Chromosome 16q
SCA5 (SPTBN2) 3rd - 4th decade
>25 years Pure cerebellar   Chromosome 11
SCA6[6] (CACNA1A) 5th - 6th decade
>25 years Downbeating nystagmus, positional vertigo
Symptoms can appear for the first time as late as 65 years old.
  CAG repeat, 19p
Calcium channel gene
SCA7[7] (ATXN7) 3rd - 4th decade
(0.5 - 60)
20 years
(1-45; early onset correlates with shorter duration)
Macular degeneration, upper motor neuron, slow saccades   CAG repeat, 3p (Ataxin 7)
SCA8[8] (IOSCA) 39 yrs
Normal lifespan Horizontal nystagmus (a rapid, involuntary, oscillatory motion of the eyeball)   CTG repeat, 13q
SCA10[9] (ATXN10) 36 years 9 years ataxia, seizures Mexico Chromosome 22q linked
pentanucleotide repeat
SCA11 30 yrs
Normal lifespan Mild, remain ambulatory (able to walk about on one's own)   15q
SCA12[10] (PPP2R2B) 33 yrs
  Head and hand tremor,
akinesia (loss of normal motor function, resulting in impaired muscle movement)
  CAG repeat, 5q
SCA13 Childhood or adulthood depending on mutation Depending on KCNC3 (a kind of gene) Mental retardation   19q
SCA14[11] (PRKCG) 28 yrs
Myoclonus (a sudden twitching of muscles or parts of muscles, without any rhythm or pattern, occurring in various brain disorders)   19q
SCA16 39 yrs
1-40 years Head and hand tremor   8q
SCA17 (TBP)         CAG repeat, 6q (TATA-binding protein)
SCA19, SCA22     Mild cerebellar syndrome, dysarthria    
SCA25 1.5-39 yrs Unknown ataxia with sensory neuropathy, vomiting and gastrointestinal pain.   2p

Others include SCA18, SCA20, SCA21, SCA23, SCA26, SCA28, and SCA29.

Four X-linked types have been described (302500, 302600, 301790, 301840), but only the first of these has so far been tied to a gene (SCAX1).


The hereditary ataxias are categorized by mode of inheritance and causative gene or 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.

Notable cases[]

Sufferers from the disease include:

  • Glyn Worsnip (2 September 1938 - 7 June 1996), British television presenter.
  • Aya Kito (19 July 1962 - 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 drama of the 1 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.
  • UK TV drama My Wind co-stars Vivienne Mah as Xue-Xiu, a girl with spincorebellar ataxia.


External links[]

  1. REDIRECT Template:CNS diseases of the nervous system