There are a few keys that help to diagnose Fragile X syndrome, which includes significant family, developmental, cognitive, and neuropsychological histories. Family history needs to screen for any learning disabilities and mental retardation. Delayed developmental milestones in early childhood may be another indicator of fragile x syndrome. Neuropsychological features like autistic-like behavior (especially poor eye contact, social avoidance, and hand biting/hand flapping) and anxiety disorder may also be present with fragile X syndrome.