ITPR1 and spinocerebellar ataxia type 15/16: Recently, it was reported that a deletion of the Itpr1 gene is associated with involuntary movements in patients of spinocerebellar ataxia type 15 (Di Gregorio et al., 2010; Marelli et al., 2011), which has been thought to be pure cerebellar ataxia (Hara et al., 2008).