In pathological samples from SCA8 patients, bidirectional (senseand antisense) expression of the SCA8 CTG·CAG expansion produces toxicnon-coding CUG expansion in RNAs from the Ataxin 8 opposite strand (ATXN8OS) anda nearly pure polyglutamine expansion protein encoded by ATXN8 (61,62). This evidence concerns the gene ATXN8 and spinocerebellar ataxia type 8.