FMR1 and fragile X syndrome: Long non-coding RNAs may participate in the pathogenesis of fragile X syndrome (FXS) and fragile X tremor ataxia syndrome (FXTAS), both of which are caused by the aberrant expansion of CGG trinucleotide, repeat in the 5′ UTR of protein-coding fragile-X mental retardation 1 gene (FMR1) [128,129].