TBP and spinocerebellar ataxia type 17: Spinocerebellar ataxia type 17 (SCA17) is an autosomal dominant cerebellar ataxia characterized by ataxia, psychiatric symptoms, parkinsonism and involuntary movement such as chorea and dystonia.[1] It is caused by an abnormal expansion of the CAG/CAA trinucleotide repeats in the TATA binding protein (TBP) gene located in chromosome 6.[2, 3]