Fragile X syndrome, or FXS, a leading genetic cause of autism, affects around one in 4,000 males and one in 6,000 females. Its symptoms include increased anxiety, intellectual disability, repetitive behaviors, social communication deficits, and abnormal sensory processing. People living with FXS generally lack the fragile X mental retardation 1 gene, or Fmr1, in their brain cells. If their cells have this gene, it is silent and not producing a protein called FMRP.
