A Study of RO4917523 in Patients With Fragile X Syndrome

Inclusion Criteria: * Adult and adolescent patients, 14-50 years of age * Diagnosis of fragile X syndrome with a confirmed fragile X mental retardation 1 (FMR1) full mutation and qualifying scores on the Aberrant Behavior Checklist (ABC) and CGI-S * Patients must agree to either remain completely abstinent or to use two effective contraceptive methods during and 3 weeks after the study Exclusion Criteria: * Previous treatment with another metabotropic glutamate (mGLU) receptor antagonist within 18 months or with RO4917523 * Participation in a clinical trial involving an investigational (unapproved) drug within 3 months or 5 times the half-life (whichever is longer) before start of this study * Any uncontrolled, unstable clinically significant psychiatric condition other than fragile X syndrome * History of suicidal behavior