Ubiquitous Cre activation yields ataxia 2 slower than straight KI (onset ~6 months). Quantitative PCR (qPCR) demonstrated a 2-fold increase in ATXN1 mRNA levels in cSCA1 × Sox2-Cre mice (in the cerebellum, brainstem, and spinal cord—and not in skeletal muscle tissue); produced less than half of the pathogenic protein compared with the unmodified SCA1 mice at 3 weeks of age. more robust weight reduction ~28 weeks, decreased distance traveled of mice in the open field (when activated only in specific cells: ChAT-Cre). Here, ATXN1 is linked to cerebellar ataxia.