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

• The area under the plasma (or serum or blood) concentration-time curve from time zero to infinity [mass x time / volume] (AUCinf) [ Time Frame: Time Frame: Day 1 (period 1): 0.5, 2, 4, 8, 12, 24 hours post-dose; Day 7 (period 2): pre-dose; 0.5, 2, 4, 8 hours post dose ] [ Designated as safety issue: No ]
• The area under the plasma (or serum or blood) concentration-time curve from time zero to the time of the last quantifiable concentration [mass x time / volume] (AUClast) [ Time Frame: Time Frame: Day 1 (period 1): 0.5, 2, 4, 8, 12, 24 hours post-dose; Day 7 (period 2): pre-dose; 0.5, 2, 4, 8 hours post dose ] [ Designated as safety issue: No ]
• Maximum observed plasma concentration (Cmax) [ Time Frame: Time Frame: Day 1 (period 1): 0.5, 2, 4, 8, 12, 24 hours post-dose; Day 7 (period 2): pre-dose; 0.5, 2, 4, 8 hours post dose ] [ Designated as safety issue: No ]

• Physical examination [ Time Frame: Screening: once anytime between Day -30 and Day -1; once anytime between 24-72 hours after Day 7 ] [ Designated as safety issue: Yes ]
• Vital signs and body measurements [ Time Frame: Screening: once anytime between Day -30 and Day -1; once anytime between 24-72 hours after Day 7 ] [ Designated as safety issue: Yes ]
• Electrocardiograms [ Time Frame: Screening: once anytime between Day -30 and Day -1; once anytime between 24-72 hours after Day 7 ] [ Designated as safety issue: Yes ]
• hematology [ Time Frame: Screening: once anytime between Day -30 and Day -1; once anytime between 24-72 hours after Day 7 ] [ Designated as safety issue: Yes ]
• blood chemistry [ Time Frame: Screening: once anytime between Day -30 and Day -1; once anytime between 24-72 hours after Day 7 ] [ Designated as safety issue: Yes ]
• neurological examination [ Time Frame: Screening: once anytime between Day -30 and Day -1; once on Day 7 ] [ Designated as safety issue: Yes ]
• Adverse events (AE) monitoring [ Time Frame: During the study (total of approximately 32 days) and 3 days after study completion ] [ Designated as safety issue: Yes ]
• Serious adverse events (SAE) monitoring [ Time Frame: During the study (total of approximately 32 days) and 30 days after study completion ] [ Designated as safety issue: Yes ]

The aim of this study is to characterize the pharmacokinetics and safety/tolerability 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