Table 1. Features of Spinocerebellar ataxias linked with abnormal neuronal Ca²⁺ signaling.

Disease subtype	Locus	Protein	Mutation	Normal repeats	SCA patient repeats	Pathology	Effect on calcium signaling
SCAl	6p	Ataxin 1	PolyQ exp	6–39	39–82	>75% PC loss	Increase
SCA2	12q	Ataxin 2	PolyQ exp	14–31	33–64	>75% PC loss	Increase
SCA3	14q	Ataxin 3	PolyQ exp	12–42	52–86	<25% PC loss	Increase
SCA5	11q	β-III spectrin	Non-repeat mutations & deletions	N/A	N/A	No data	Increase
SCA6	19p	CACNA1A	PolyQ exp	4–18	19–30	>75% PC loss	Increase/decrease
SCA14	19q	PKCγ	Non-repeat mutations	N/A	N/A	No data	Increase/decrease
SCA15/16	3p	ITPR1	Non-repeat deletions or mutations	N/A	N/A	No data	Decrease

Adapted from [24], Number of repeats adapted from [20], SCA pathology adapted from [16]

PolyQ exp Polyglutamine expansion, N/A Not applicable