These most commonly include: CGG repeats in fragile X mental retardation 1 (FMR1) gene in Fragile X-associated syndromes [6]; thousands of CTG/CCTG repeats in the myotonic dystrophies (DM1 and DM2) [7,8] and trinucleotide, pentanucleotide or hexanucleotide repeats in non-polyQ SCAs [9]; GAA repeat expansions in Friedreich's ataxia [10]; thousands of GGGGCC repeats in chromosome 9 open reading frame 72 (C9ORF72) in the most common genetic forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) [11,12]. Here, FMR1 is linked to frontotemporal dementia.