CLOCK and fragile X syndrome: Two studies reported by Dockendorff et al. and Morales et al. demonstrated that although the rhythmic mRNA and protein expressions of the core clock genes per and tim was normal in the FXS Drosophila melanogaster, FMRP deficiency results in behavioral phenotypes of FXS Drosophila melanogaster including arrhythmic eclosion and locomotor activity [5, 6].