We are also interested in investigating the implication of four novel genes: CAG polymorphic repeat of the DRPLA and ATXN1 genes and CTG polymorphic repeat of the JPH3 and DMPK genes. DRPLA, ATXN1, DMPK, and JPH3 are responsible, respectively, for the dentatorubral-pallidoluysian atrophy disorder (DRPLA), spinocerebellar ataxia type 1 (SCA1), myotonic dystrophy 1 (DM1), and Huntington's disease-like-2 (HDL2). This evidence concerns the gene ATXN1 and spinocerebellar ataxia type 1.