The purpose of this study is to determine vitamin C and vitamin E in combination are effective in the treatment of cognitive and behavior disorder in children with fragile X syndrome.

The combination of vitamin E and vitamin C supplementation has been associated with a lower prevalence (-78%) and incidence (-64%) of Alzheimer's disease in the elderly population. It has recently been shown that dietary vitamin E supplementation reduces the production of free radicals inhibiting NADPH oxidase activity in circulating neutrophils. Another work describes the inhibition of glutamate release by activated microglia in cell cultures incubated with vitamin E, effect that can prevent excitotoxicity.

The investigators propose to evaluate the effectiveness of treatment in neurodevelopmental disorders affected by fragile X syndrome (FXS) with lipophilic compounds antioxidants such as tocopherol and hydrophilic compounds antioxidants such as ascorbic acid, which regulate oxidative stress and improve learning and behavioral mouse model and humans.

Our group has positive results in the use of this combination of antioxidants as a treatment for fragile X syndrome in adolescents. This disease has developed previous clinical trials with EUDRACT codes: 2009-017837-23 and 2013-004276-35.

The use of the combination of vitamin C and E in the treatment of cognitive and behavioral disorder in FXS, is patented PCT-050 187 with reference number 2011070875

This combination will be administered as a single oral dose with a total dose of 10mg / kg / day for each of the vitamins. This dose is maintained within the therapeutic range of both antioxidants.

Inclusion Criteria:

1. Diagnosis of Fragile X syndrome by genetic testing of molecular biology, full mutation result methylation.
2. Having an older age of 1 year and less than 9 years
3. Having signed the informed consent document before starting their participation in the trial.

Exclusion Criteria:

1. Any advanced, severe or unstable disease.
2. Individuals with other psychiatric diagnosis as the first diagnosis.
3. It have been suffered serious medical problems in the last 12 months.
4. Be taking more than 100 mg of vitamin E or C a day in the last month.
5. Having physical, mental or sensory impairments that prevent the assessment of effectiveness.
6. Hypersensitivity to any component of the preparation.
7. Liver failure or severe renal or previous history of kidney stones.
8. Any treatment regimen, including treatment with psychotropic drugs and / or anticonvulsant therapy that has not been stable for a period ≥ 4 weeks before randomization.
9. Current treatment with more than two psychoactive medications, excluding medication used specifically for the control of seizures.
10. Hypoprothrombinemia secondary to vitamin K deficiency
11. Sensitivity to any of the compounds of formula treatment.
12. Patients diagnosed with congenital or idiopathic methemoglobinemia for diagnosis of glucose-6-phosphate dehydrogenase deficiency.
13. Use of oral anticoagulants, iron or vitamin A.
14. Forecast initiate or change pharmacological or no pharmacological interventions during the course of the study.
15. Patients weighing less than 4.2 kg