A Study of RO4917523 in Pediatric Patients With Fragile X Syndrome

Inclusion Criteria: * Children and adolescents, 5 to 13 years of age * Diagnosis of fragile X syndrome based on prior DNA testing confirming Fragile X Mental Retardation 1 (FMR1) full mutation and qualifying scores on the ABC and CGI-S Exclusion Criteria: * Previous treatment with another mGlu5 receptor antagonist within the prior 3 months * Participation in a clinical trial involving an investigational drug (unapproved) or non-drug treatment within the prior 6 weeks or 5 times the half-life (whichever is longer) before the start of this study * Any uncontrolled, unstable clinically significant psychiatric condition other than fragile X syndrome * History of suicidal behavior * Other protocol defined inclusion/exclusion criteria may apply