The present invention provides small interfering RNAs, short hairpin RNAs and vectors and pharmaceutical compositions comprising the siRNA and shRNAs. Methods for treating a neurodegenerative disorder, namely SCA-1 are also described. Particularly, the invention provides a small interfering RNA consisting of a first and second strand wherein said first strand is encoded by a DNA sequence comprising SEQ ID NO. 1 or SEQ ID NO. 2.