FMR1 and fragile X syndrome: Development of Fragile X Syndrome (FXS) or the related disease Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) is caused by the presence of a triple CGG repeat motif in the 5′ untranslated region (5′-UTR) of the FMR1 gene (Khalil et al., 2008; Peschansky et al., 2015; Huang et al., 2019).