Given that the exact mechanism of SCA3 remains unsolved, it is essential to decipher the pathogenesis of SCA3 disease through in-depth analysis of the phenotypes in molecular and cellular levels, such as degeneration and potassium channel dysfunction in Purkinje cells, mitochondrial dysfunction and oxidative stress. The gene discussed is ATXN3; the disease is Spinocerebellar ataxia type 3.