CAPN1 and Spinocerebellar ataxia type 3: Indeed, experimental evidence suggests that the activity of calpain enzymes may be increased in cells obtained from SCA3 patients [38,40], a phenotype that can be ameliorated via the genetic silencing of calpain-1 [40] or worsened via genetic silencing of calpastatin, an endogenous calpain inhibitor [37].