Considered a rare disorder affecting both genders , it first becomes apparent during childhood with displays of language delay and behavioural symptoms.Main aim : To show whether the combination of 10 mg/kg/day of ascorbic acid ( vitamin C ) and 10 mg/kg/day of - tocopherol ( vitamin E ) reduces FXS symptoms among male patients ages 6 to 18 years compared to placebo treatment , as measured on the standardized rating scales at baseline , and after 12 and 24 weeks of treatment.Secondary aims : To assess the safety of the treatment .