FMR1 and fragile X syndrome: For example, the intellectual disability and autism-related gene, FMR1, mutated in Fragile X Syndrome, is necessary for developmental and experience-dependent synaptic pruning (Patel et al., 2014; Nagaoka et al., 2016) as well as pruning in response to MEF2VP16 (Pfeiffer et al., 2010).