Yes, in some but not all cases, and more so in males. Fragile X syndrome is caused by a change to the FMR1 gene on the X-chromosome. This gene helps the brain function. It affects both boys and girls, and it is a common cause of inherited cognitive impairment and intellectual disability.  Most males with Fragile X syndrome exhibit mild to moderate intellectual disability, whereas approximately one-third of females with the syndrome are cognitively impaired.