Fragile X syndrome
What are the main cognitive and behavior symptoms of fragile X syndrome?
Fragile X syndrome leads to developmental delays including speech delays and intellectual disability (formerly known as mental retardation) of varying degrees from severe cognitive impairment to mild learning disabilities. Individuals with fragile X syndrome can also have extreme anxiety, sensory disorders, social withdrawal, aberrant behavior, aggressive behavior, and stereotypic (repetitive and without function) behaviors like hand-flapping and body rocking. Many of these behaviors, including gaze avoidance, can cause fragile X syndrome to be mistaken for autism. While people with fragile X syndrome can also have autism, fragile X syndrome is a separate disorder with additional signs and symptoms.
Huddleston LB, Visootsak J, Sherman SL. Cognitive Aspects of Fragile X syndrome. Wiley interdisciplinary reviews Cognitive science. 2014;5(4):501-508. doi:10.1002/wcs.1296.
Kidd, Sharon A., et al. "Fragile X syndrome: a review of associated medical problems." Pediatrics 134.5 (2014): 995-1005.