Table 1. Human ataxias not associated with CAG repeats.
| Ataxia | Gene | Protein | Phenotype | Mutation | ITPR1 | Protein function | OMIM |
|---|---|---|---|---|---|---|---|
| SCA15, SCA16 | ITPR1 | ITPR1 | Pure | Deletion | Yes | ITPR1 is an intracellular calcium-release channel gated by IP3 | 606658 |
| SCA14 | PRKCG | PKCγ | Pure | Missense | M | PKCγ is a kinase expressed in cerebellum | 605361 |
| QG ataxia | CA8 | Carbonic anhydrase 8 | Pure | Missense | Yes | CA8 is an ITPR1 antagonist; quadrupedal gait ataxia | 613227 |
| SCA5 | SPTBN2 | Spectrin β | Pure | Deletion, missense | M | Spectrin β is an EAAT4 (glutamate transporter) and GluRδ2 anchor | 600224 |
| EA6 | SLC1A3 | EAAT1 | Episodic, fairly pure | Missense | M | EAAT1 is a glutamate transporter | 612656 |
| EA2 (SCA6) | CACNA1A | Cav2.1 | Episodic and pure | Nonsense, missense, CAG repeat | Yes | Cav2.1 is the main P-type calcium channel in PCs. Nonsense/missense mutations cause episodic ataxia type 2; expansion of a CAG repeat causes SCA6, a pure ataxia | 108500 183086 |
| EA5 | CACNB4 | CavB4 | Episodic Pure | Nonsense, missense | Yes | CavB4 is an accessory subunit that regulates P-type channels encoded by Cav2.1 | 601949 |
| EA1 | KCNA1 | Kv1.1 | Episodic Pure | Missense | M | Kv1.1 contributes to rheobase and neurotransmitter release of at terminals | 160120 |
| SCA13 | KCNC3 | Kv3.3 | Ataxia + | Missense | M | Kv3 channels contribute to repolarization of dendritic Ca2+ spikes in PCs | 605259 |
| SCA27 | FGF14 | Pure | Missense, nonsense | No | FGF14, intracelluar fibroblast growth factor plays a role in localising Na(v) channels. | 609307 | |
| SCA10 | ATXN10 | Ataxin-10 | Ataxia +, also pure | (ATTCT)n intron | ?? | Some present with non-consensus repeat units; Ataxin-10 function unknown | 603516 |
| SCA11 | TTBK2 | Pure | Frameshift | ?? | TTBK2 function unknown | 604432 | |
| SCA4 | PLEKHG4 | Puratrophin-1 | Pure | Substitution 5′UTR | No | Puratrophin-1 function is largely unknown; could be involved in Golgi cytoskeleton (associated with ataxia in Japanese families) | 117210 |
| SCA8 | ATXN8OS (KLHL1) | Ataxia + | (CTG)n 3′UTR | M | Repeats located in the 3′UTR. Endogenous antisense RNA overlaps the KLHL1 gene. KLHL1 is an actin-organizing protein | 608769 |
EA, episodic ataxia; QG, quadrupal gait; ITPR1, likelihood of interaction with ITPR1-dependent signaling; SCA, Spinocerebellar ataxia. m, maybe; ??, protein function unknown.