The role of Ca2+ signaling in the pathogenesis of SCA2 is supported by the genetic inverse correlation between CAG-repeat length in the CACNA1A gene and the age of disease onset [194] and further reinforced by finding that mutant Atxn2 has been shown to interact with the cytosolic COOH-terminal of IP3R1 by increasing the sensitivity of the receptor to its ligand [20]. The gene discussed is ITPR1; the disease is spinocerebellar ataxia type 2.