SCA 17 is a rare form of autosomal dominant neurodegenerative disease caused byexpansion of a CAG triplet repeat in the gene structure of the protein linked toTATA, called the TBP gene (located on chromosome 6q27), which is a factor ofinitial transcription.2-4,54,55 The diseasewas first described in Japan by Koide et al. in a 14 year-old female patientwith clinical onset at 6 years of age, ataxia syndrome, and subsequentintellectual deterioration. The gene discussed is TBP; the disease is cerebellar ataxia.