Spinocerebellar ataxia is an autosomal dominant disorder and a highly genetically heterogeneous disorder for which the gold standard is molecular genetics (i.e., genetic testing), in addition to tests such as CT, MRI, and electromyography. Spinocerebellar ataxia tends to develop in adulthood and is inherited. The most characteristic genetic defect is CAG amplification, and the higher the number of CAG amplifications, the earlier the age of onset. It can be identified by genetic testing. Molecular genetic testing (i.e., genetic testing) can confirm the diagnosis of cerebellar ataxia and its subtypes based on the history of ataxia and family history, as well as the combination of symptoms. Genetic testing should be done in a hospital or company, and then the doctor will guide the treatment and medication.