FMR1 and Intellectual disability: Loss of FMRP results in the characteristic features of FXS, including mild to severe intellectual disability, cognitive impairments, seizures, poor language development, altered physical features such as macroorchidism and facial dysmorphisms, and behavioral problems such as social difficulties, anxiety, hyperactivity, hypersensitivity to sensory stimuli, and other autistic-like behaviors [4,5,6,7,8].