Genetic and clinical analysis of spinocerebellar ataxia type 8 repeat expansion in Italy.

Abstract
SPINOCEREBELLAR ataxia type 8 (SCA8) is the first form of ataxia caused by a CTG triplet repeat expansion. This disorder, originally described in a family characterized by pure cerebellar ataxia with slow disease progression, shows clinical features similar to those of other spinocerebellar ataxias (SCAs), including limb and truncal ataxia, dysarthria, and nystagmus. The SCA8 has been distinguished among triplet disease disorders both in terms of the transcribed repeat motif (CTG) and for its location in the noncoding region of the gene, resulting in an untranslated expansion at the 3′ end of RNA.1 The existence of an antisense transcript, encoding a novel actin-binding protein (KLHL1), has been recently reported,2 suggesting that the pathogenic effect of SCA8 expansion may result in an alteration of KLHL1 messenger RNA stability or processing. However, the role of CTG expansion in the pathogenesis of SCA8 and the molecular mechanism responsible for the disease remain to be clarified.