The amplification of CGG triplet in 5′-UTR of the fragile X mental retardation 1 (FMR1) gene may lead to Fragile X disorders (FXTAS), while (CAG)n in the exon of ataxin3 (ATXN3) may cause Spinocerebellar Ataxia 3 (SCA3). Here, FMR1 is linked to Machado-Joseph disease.