HSPA5 and cerebellar ataxia: Consistently, genetic disruption of the SIL 1 gene that encodes a GRP78/BiP co-chaperone in woozy mutant mice leads to protein accumulation, ER stress, and selective cerebellar neuronal loss; homozygous woozy mutant mice develop ataxia between 3 and 4 months of age and have significant loss of cerebellar Purkinje cells [18].