Patient case (clinical description): A 15-year-old boy with mild intellectual disability is brought to the office by his parents for a routine physical examination.  The boy is going to a school for students with learning disabilities.  The patient was adopted, and his immunizations are up to date.  Review of the patient's medical records is notable for cytogenetic studies that showed a small gap near the tip of the long arm of the X chromosome, which is consistent with fragile X syndrome, an X-linked disorder. The defect is an unstable expansion of trinucleotide repeats (CGG) in the fragile X mental retardation 1 (FMR1) gene, located on the long arm of the X chromosome. He is not using any medications and vital signs are within normal levels. His blood chemistry analysis as bellow:
Blood Chemistry Value      Normal Range     Patient Value
Glucose                    90-120 mg/dl     95 mg/dl
BUN (Blood Urea Nitrogen)  7-24 mg/dl       10 mg/dl
Creatinine                 0.7-1.4 mg/dl    0.8 mg/dl
Calcium                    8.5-10.5 mg/dl   9 mg/dl
Sodium                     134-143 mEq/L    135 mEq/L
Potassium                  3.5-4.5 mEq/L    3.7 mEq/L
Chloride                   95-108 mEq/L     98 mEq/L
CO2                        20-30 mEq/L      25 mEq/L
Blood pH                   7.38-7.42        7. 39

Patient's own account: My husband and I brought our 15-year-old son to the clinic for his routine exam. My son is going to school for special needs students. We adopted him a few years ago. His vaccinations are up to date. He already passed some chromosome testing and they found that he has a fragile X syndrome. The doctor told us that it comes from repeats in the fragile X chromosome. My son is not using any medication and his blood pressure temperature and breathing were normal during the exam. He also did a blood test. The results came back and showed that his blood sugar urea creatinine calcium sodium potassium chloride CO2 and blood pH were all within the normal range.

Clinical trial: A Trial of Metformin in Individuals With Fragile X Syndrome (Met)

Eligibility criteria:
Inclusion Criteria:

          -  Subject has Fragile X syndrome with a molecular genetic confirmation of the full FMR1
             mutation (>200 CGG repeats) or the other loss of function mutations of the FMR1 gene
             (SNVs and deletions of the gene).

          -  Subject is a male or non-pregnant, non-lactating female age 6 to 25 years, inclusive.

          -  Subjects who are capable of becoming pregnant must use an acceptable method of birth
             control for the duration of the study. Acceptable forms of birth control include
             abstinence (only for subjects who are not sexually active), intrauterine devices in
             place for at least 3 months, oral contraceptives, surgical sterilization, or adequate
             barrier methods.

          -  Subject must have a caregiver (parent, guardian, or other legally authorized
             representative) who is willing to participate in the whole study.

          -  Subject and caregiver are able to attend the clinic regularly and reliably.

          -  Subject and/or subject's caregiver is able to understand, read, write and speak
             English or French fluently to complete study-related materials.

          -  For subjects who are not their own legal guardian, subject's caregiver is able to
             understand and sign an informed consent to participate in the study.

          -  The use of concomitant medication must be stable, in terms of dose and dosing regimen,
             for at least 4 weeks prior to Screening and must remain stable during the period
             between first visit (Screening) and the commencement of the study; every effort should
             be made to maintain stable regimens of allowed concomitant medications from the time
             of commencement of double-blind study medication until the last study assessment.

          -  Behavioral/educational treatments must be stable for 4 weeks prior to first visit
             (Screening) and must remain stable during the period between Screening and the
             commencement of randomized double-blind study medication.

          -  Overall IQ, as assessed at Screening on the Leiter-III, is not higher than 79, and
             subject must speak at least occasional 3-word phrases.

        Exclusion Criteria:

          -  Families that are not cooperative and will not follow through with the demands of this
             study.

          -  Subject has a life-threatening medical problem or other major systemic illness that
             compromises health or safety and/or would interfere with this study.

          -  Age younger than 6 or older than 25 years.

          -  History of intolerable adverse events with metformin.

          -  Current or recent metformin treatment (within the past 4-months).

          -  BMI inferior to 2 standard deviations below the mean for age using the World Health
             Organization scale.

          -  Serum creatinine > 1.4 mg/dl (female) or > 1.5 mg/dl (male).

          -  History of metabolic acidosis or a condition with lactic acidosis.

          -  Severe Vitamin B12 deficiency.

          -  Pregnancy at screening or unwillingness to use acceptable method of birth control, if
             applicable.

          -  IQ higher than 79 on the Leiter-III at Screening.
No condition on gender to be admitted to the trial.
No healthy subjects accepted to join the trial.
Subject must be at least 6 Years old.
Subject must be at most 25 Years

Eligibility (NLI label): Entailment