Disorder | Distinguishing features | Gene locus and protein | |
SCA1 | Pyramidal signs, peripheral neuropathy | ATXN1 | CAG repeat, ataxin-1 |
SCA2 | Slow saccades; less often myoclonus, areflexia | ATXN2 | CAG repeat, ataxin-2 |
SCA3 (MJD) | Slow saccades, persistent stare, extrapyramidal signs, peripheral neuropathy | ATXN3 | CAG repeat, ataxin-3 (MJD1) |
SCA4 | Sensory neuropathy | 16q22.1 | |
SCA5 | Early onset but slow progression | SPTBN2 | Beta III spectrin |
SCA6 | May have very late onset, mild, may lack family history, nystagmus | CACNA1A | CAG repeat, alpha 1A P/Q calcium channel subunit |
SCA7 | Macular degeneration | ATXN7 | CAG repeat, ataxin-7 |
SCA8 | Mild disease | ATXN8 ATXN8OS | CTG*CAG repeat |
SCA9 | Not assigned | ||
SCA10 | Generalized or complex partial seizures | ATXN10 | ATTCT repeat, ataxin-10 |
SCA11 | Mild disease | TTBK2 | Tau tubulin kinase-2 |
SCA12 | Tremor, dementia | PPP2R2B | CAG repeat in 5' region, protein phosphatase 2A |
SCA13 | Intellectual disability | KCNC3 | Voltage gated potassium channel KCNC3 |
SCA14 | Intermittent myoclonus with early onset disease | PRKCG | Protein kinase C gamma |
SCA15/16 | Slowly progressive | ITPR1 | Inositol 1,4,5-triphosphate receptor 1 |
SCA17 | Gait ataxia, dementia | TBP | CAG repeats, TATA binding protein |
SCA18 | Pyramidal signs, weakness, sensory axonal neuropathy | 7q22-q32 | |
SCA19/22 | Predominantly cerebellar syndrome, sometimes with cognitive impairment or myoclonus | KCND3 gene | Voltage-gated potassium channel Kv4.3 |
SCA20 | Palatal tremor and dysphonia | 11q12 | |
SCA21 | Mild to severe cognitive impairment | TMEM240 | Transmembrane protein 240 |
SCA23 | Distal sensory deficits | PDYN | Prodynorphin |
SCA24 | Recessive inheritance; redesignated as SCAR4 | 1p36 | |
SCA25 | Sensory neuropathy, facial tics, gastrointestinal symptoms | 2p21-p13 | |
SCA26 | Pure cerebellar ataxia | EEF2 | Eukaryotic translation elongation factor 2 |
SCA27 | Cognitive impairment | FGF14 | Fibroblast growth factor 14 |
SCA28 | Ophthalmoparesis and ptosis | AFG3L2 | Catalytic subunit of the mitochondrial AAA protease |
SCA29 | Early onset, nonprogressive ataxia; may be an allelic variant of SCA15 | 3p26 | |
SCA30 | Slowly progressive, relatively pure ataxia | 4q34.3-q35.1 | |
SCA31 | Decreased muscle tone | BEAN | (TGGAA)n repeat |
SCA32 | Cognitive impairment, affected males with azoospermia and testicular atrophy | 7q32-q33 | |
SCA33 | Not assigned | ||
SCA34 | Skin lesions consisting of papulosquamous erythematous ichthyosiform plaques | ELOVL4 | ELOVL fatty acid elongase 4 |
SCA35 | Late onset, slowly progressive gait and limb ataxia | TGM6 | Transglutaminase 6 |
SCA36 | Late onset, truncal ataxia, dysarthria, variable motor neuron disease and sensorineural hearing loss | NOP56 | GGCCTG repeat |
SCA37 | Late onset, falls, dysarthria, clumsiness, abnormal vertical eye movements | 1p32 | |
SCA38 | Slowly progressive pure cerebellar phenotype | ELOVL5 | ELOVL fatty acid elongase 5 |
SCA39 | Not assigned | ||
SCA40 | Hyperreflexia and spasticity | CCDC88 | Coiled-coil domain-containing 88C |
SCA42 | Early motor delay, hypotonia, speech delay, severe intellectual disability, ataxia | CACNA1G | Voltage-gated calcium channel subunit alpha 1G |
SCA44 | Ataxia, dysarthria, dysmetria, dysphagia | GRM1 | Metabotropic glutamate receptor 1 |
SCA45 | Limb and gait ataxia, downbeat nystagmus, dysarthria | FAT2 | Protocadherin Fat 2 |
SCA46 | Neuropathy and sensory ataxia affecting lower limbs more than upper limbs, cerebellar atrophy | PLD3 | 5'-3' exonuclease PLD3 |
SCA47 | Early-onset developmental disability, ataxia, seizure; later-onset ataxia, dysarthria, dysmetria | PUM1 | Pumilio homolog 1 |
SCA48 | Gait ataxia, cognitive dysfunction in adulthood | STUB1 | CHIP, an E3 ubiquitin-protein ligase |
DRPLA | Chorea, seizures, myoclonus, dementia | ATN1 | CAG repeat, atrophin-1 |