Table 1.
Autosomal dominant hereditary ataxias.
| Disease Namea | Gene | Average onset (range in years) | Average duration (range in years) | Distinguishing featuresb |
|---|---|---|---|---|
| SCA1 | ATXN1 | 3rd–4th decade (< 10 to >60) | 15 years (10–28) | Pyramidal signs, peripheral neuropathy |
| SCA2 | ATXN2 | 3rd–4th decade (< 10 to >60) | 10 years (1–30) | Slow saccadic eye movements, peripheral neuropathy, decreased DTRs, dementia |
| SCA3 | ATXN3 | 4th decade (10–70) | 10 years (1–20) | Pyramidal and extrapyramidal signs; lid retraction, nystagmus, decreased saccade velocity; amyotrophy fasciculations, sensory loss |
| SCA4 | 16q22.1 | 4th–7th decade (19–72) | Decades | Sensory axonal neuropathy, deafness; may be allelic with 16q22- linked SCA |
| SCA5 | SPTBN2 | 3rd–4th decade (10–68) | >25 years | Early onset, slow course; first reported in descendants of Abraham Lincoln |
| SCA6 | CACNA1A | 5th–6th decade (19–71) | >25 years | Sometimes episodic ataxia, very slow progression |
| SCA7 | ATXN7 | 3rd–4th decade (0.5–60) | 20 years (1–45; early onset correlates with shorter duration) | Visual loss with retinopathy |
| SCA8 | ATXN8I | 4th decade (1–65) | Normal life span | Slowly progressive, sometimes brisk DTRs, decreased vibration sense; rarely, cognitive impairment |
| ATXN80S | ||||
| SCA10 | ATXN10 | 4th decade (12–48) | 9 years | Occasional seizures; most families are of Native American background |
| SCA11 | TTBK2 | Age 30 years (15–70) | Normal life span | Mild, remain ambulatory |
| SCA12 | PPP2R2B | 4th decade (8–62) | Slowly progressive ataxia; action tremor in the 30s; hyperreflexia; subtle Parkinsomism possible; cognitive/psychiatric disorders including dementia | |
| SCA13 | KCNC3 | Childhood or adulthood | Unknown | Mild intellectual disability, short stature |
| SCA14 | PRKCG | 3rd–4th decade (3–70) | Decades (1–30) | Early axial myoclonus |
| SCA15 | ITPR1 | 4th decade (7–66) | Decades | Pure ataxia, very slow progression |
| SCA16 | SCA16 | Age 39 years (20–66) | 1–40 years | Head tremor; one Japanese family |
| SCA17 | TBP | 4th decade (3–55) | >8 years | Mental deterioration; occasional chorea, dystonia, myoclonus |
| SCA18 | 7q22-q32 | Adolescence (12–25) | Decades | Ataxia with early sensory/motor neuropathy, nystagmus, dysarthria, decreased tendon reflexes, muscle weakness, atrophy, fasiculations, Babinski responses |
| SCA 19/22 | KCND3 | 4th decade (10–51) | Decades | Slowly progressive, rare cognitive impairment, myoclonus, hyperreflexia |
| SCA20 | 11q12.2 | 5th decade (19–64) | Decades | Early dysarthria, spasmodic dysphonia, hyperreflexia, bradykinesia; calcification of the dentate nucleus |
| 11q12.3 | ||||
| SCA21 | SCA21 | 6–30 | Decades | Mild cognitive impairment |
| SCA23 | PDYN | 5th–6th decade | >10 years | Dysarthria, abnormal eye movements, reduced vibration and position sense; one Dutch family; neuropathology |
| SCA25 | SCA25 | (1.5–39) | Unknown | Sensory neuropathy; one French family |
| SCA26 | EEF2 | (26–60) | Unknown | Dysarthria, irregular visual pursuits; one Norwegian-American family; MRI: cerebellar atrophy |
| SCA27 | FGF14 | Age 11 years (7–20) | Decades | Early-onset tremor; dyskinesia, cognitive deficits; one Dutch family |
| SCA28 | AFG3L2 | Age 19.5 years (12–36) | Decades | Nystagmus, opthalmoparesis, ptosis, increased tendon reflexes; two Italian families |
| SCA29 | 3p26 | Early childhood | Lifelong | Learning deficits |
| SCA30 | 4q34.3–q35.1 | (45–76) | Lifelong | Hyperreflexia |
| SCA31 | BEAN1 | 5th–6th decade | Lifelong | Normal sensation |
| SCA35 | TGM6 | 43.7 ± 2.9 (40–48) years | 15.9 ± 8.8 (5–31) years | Hyperreflexia, Babinski respsonses; spasmodic torticollis |
| SCA36 | NOP56 | 52.8 ± 4.3 years | Decades | Muscle fasiculations, tongue atrophy, hyperreflexia |
DTR, deep tendon reflex.
a
SCA9 has not been assigned.
b
All have gait ataxia.
Reprinted by permission from Macmillan Publishers Ltd: Genetics in Medicine (Jayadev and Bird, 2013), copyright (2013).