Analogous to the human phenotype, CHIP mutation rodent models also exhibit progressive cerebellar ataxia, cerebellar neuronal degeneration and death, concomitant with a marked increase in the cerebral phosphodiesterase 9A (PDE9A) protein level, which progressively increases as the disease progresses (Shi et al, 2018b). This evidence concerns the gene STUB1 and cerebellar ataxia.