Clinical Study to Assess the Pharmacokinetics, Safety and Tolerability of Single and Multiple Oral Doses of AFQ056 in Children With Fragile X Syndrome (FXS)

Inclusion Criteria:

- Genetically confirmed diagnosis of FXS

- At Screening and first baseline, vital signs, body weight and body mass index (BMI)
must be age-specific within normal ranges.

Exclusion Criteria:

- Use of any other investigational drug within 30 days or 5 half-lives (whichever is
longer) of the investigational drug prior to screening until end of study visit.

- History of hypersensitivity to AFQ056 or any mGluR antagonist.

- Female patients who are confirmed or suspected to be sexually active.

- History or presence of any clinically significant disease of any major system organ
class, within the past 2 years prior to screening including but not limited to
psychiatric, neurological, cardiovascular, endocrine, metabolic, renal, or
gastrointestinal disorders (except for typical features of FXS).

- Smokers.

- Loss of ≥10% of total blood volume within 8 weeks (or less if required for this age
group and/or by local regulation) prior to dosing or longer if required for this age
group and/or by local regulation.

- Significant illness that did not completely resolve at least four weeks prior to the
first baseline visit.

- Any abnormal laboratory values at screening or first baseline that are in the opinion
of the investigator clinically significant and may jeopardize the safety of the study
subject.

- Use of (or use within at least 5 half lives before dosing) concomitant medications
that are strong/moderate inhibitors or inducers of CYP1A1/2, CYP2C9/19 or CYP3A4

- History or presence of Hepatitis B/C or HIV at screening