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  • The discussion refers to a "1.9" as a likelihood, but the example on this page doesn't have that number. Typo? Is is based on a different example?

Fixed Cariaso 21:42, 1 June 2008 (UTC)

Spinocerebellar Atrophy[edit]

Are these included in SNPedia results? If not, is there any way someone can add them?

Many SCAs below fall under the category of polyglutamine diseases, which are caused when a disease-associated protein (i.e. ataxin-1, ataxin-3, etc.) contains a glutamine repeat beyond a certain threshold. In most dominant polyglutamine diseases, the glutamine repeat threshold is approximately 35, except for SCA3 which is beyond 50. Polyglutamine diseases are also known as "CAG Triplet Repeat Disorders" because CAG is the codon which codes for the amino acid glutamine. Many prefer to refer to these also as polyQ diseases since "Q" is the one-letter reference for glutamine.


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 (10–35) 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 (1–30) Diminished velocity saccades areflexia (absence of neurologic reflexes) Cuba CAG repeat, 12q SCA3[4] (MJD) (ATXN3) 4th decade (10–70) 10 years (1–20) Also called Machado-Joseph disease (MJD)[5] Gaze-evoked nystagmus (a rapid, involuntary, oscillatory motion of the eyeball) upper motor neuron slow saccades Azores (Portugal) CAG repeat, 14q SCA4 (PLEKHG4) 4th–7th decade (19–72) Decades areflexia (absence of neurologic reflexes) Chromosome 16q SCA5 (SPTBN2) 3rd–4th decade (10–68) >25 years Pure cerebellar Chromosome 11 SCA6[6] (CACNA1A) 5th–6th decade (19–71) >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 (18–65) Normal lifespan Horizontal nystagmus (a rapid, involuntary, oscillatory motion of the eyeball), instability, lack of coordination CTG repeat,[9] 13q SCA10[10] (ATXN10) 36 years 9 years ataxia, seizures Mexico Chromosome 22q linked pentanucleotide repeat SCA11 30 yrs (15–70) Normal lifespan Mild, remain ambulatory (able to walk about on one's own) 15q SCA12[11] (PPP2R2B) 33 yrs (8–55) 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[12] (PRKCG) 28 yrs (12–42) Decades (1–30) Myoclonus (a sudden twitching of muscles or parts of muscles, without any rhythm or pattern, occurring in various brain disorders) 19q SCA16 39 yrs (20–66) 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 SCA27[13] 15–20 yrs Unknown ataxia with low cognition, dyskinesias and tremor. FGF14 13q34 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).

There is already a Spinocerebellar ataxia medical condition set in SNPedia. What would be needed is to add any appropriate SNP pages for this condition and include a link to the Spinocerebellar ataxia page. Then those SNPs will show up under the medical section in Promethease. If you don't know how to add SNP pages then you can add a list here and someone will create the appropriate pages. --Jlick 15:04, 24 July 2012 (UTC)