FMR1 and fragile X syndrome: The human fragile X mental retardation 1 gene (FMR1; HGNC:3775) contains a (CGG)n trinucleotide repeat that is responsible for a family of heritable disorders affecting both early neurodevelopment (fragile X syndrome; FXS) and late-onset neurodegeneration (fragile X-associated tremor/ataxia syndrome; FXTAS) [1]–[4].