| SCA1 (autosomal dominant type 1) | 6p22-p23 with CAG repeats (exonic); leucine-rich acidic nuclear protein (LANP), region-specific interaction protein Ataxin-1 | Ataxia with ophthalmoparesis, pyramidal and extrapyramidal findings; genetic testing is available; 6% of all autosomal dominant (AD) cerebellar ataxia |
| SCA2 (autosomal dominant type 2) | 12q23-q24.1 with CAG repeats (exonic) Ataxin-2 | Ataxia with slow saccades and minimal pyramidal and extrapyramidal findings; genetic testing available; 13% of all AD cerebellar ataxia |
| Machado-Joseph disease/SCA3 (autosomal dominant type 3) | 14q24.3-q32 with CAG repeats (exonic); codes for ubiquitin protease (inactive with polyglutamine expansion); altered turnover of cellular proteins due to proteosome dysfunction MJD–ataxin-3 | Ataxia with ophthalmoparesis and variable pyramidal, extrapyramidal, and amyotrophic signs; dementia (mild); 23% of all AD cerebellar ataxia; genetic testing available |
| SCA4 (autosomal dominant type 4) | 16q22.1-ter; pleckstrin homology domain-containing protein, family G, member 4 (PLEKHG4; puratrophin-1: Purkinje cell atrophy associated protein-1, including spectrin repeat and the guanine-nucleotide exchange factor, GEF for Rho GTPases) | Ataxia with normal eye movements, sensory axonal neuropathy, and pyramidal signs; genetic testing available |
| SCA5 (autosomal dominant type 5) | 11p12-q12; β-III spectrin mutations; (SPTBN2); stabilizes glutamate transporter EAAT4; descendants of President Abraham Lincoln | Ataxia and dysarthria; genetic testing available |
| SCA6 (autosomal dominant type 6) | 19p13.2 with CAG repeats in α1A-voltage–dependent calcium channel gene (exonic); CACNA1A protein, P/Q type calcium channel subunit | Ataxia and dysarthria, nystagmus, mild proprioceptive sensory loss; genetic testing available |
| SCA7 (autosomal dominant type 7) | 3p14.1-p21.1 with CAG repeats (exonic); ataxin-7; subunit of GCN5, histone acetyltransferase-containing complexes; ataxin-7 binding protein; Cbl-associated protein (CAP; SH3D5) | Ophthalmoparesis, visual loss, ataxia, dysarthria, extensor plantar response, pigmentary retinal degeneration; genetic testing available |
| SCA8 (autosomal dominant type 8) | 13q21 with CTG repeats; noncoding; 3′ untranslated region of transcribed RNA; KLHL1AS | Gait ataxia, dysarthria, nystagmus, leg spasticity, and reduced vibratory sensation; genetic testing available |
| SCA10 (autosomal dominant type 10) | 22q13; pentanucleotide repeat ATTCT repeat; noncoding, intron 9 | Gait ataxia, dysarthria, nystagmus; partial complex and generalized motor seizures; polyneuropathy; genetic testing available |
| SCA11 (autosomal dominant type 11) | 15q14-q21.3 by linkage | Slowly progressive gait and extremity ataxia, dysarthria, vertical nystagmus, hyperreflexia |
| SCA12 (autosomal dominant type 12) | 5q31-q33 by linkage; CAG repeat; protein phosphatase 2A, regulatory subunit B, (PPP2R2B); protein PP2A, serine/threonine phosphatase | ...