Treatment with valproic acid ameliorates ADHD symptoms in fragile X syndrome boys.

Fragile X syndrome (FXS) is the leading cause of inherited mental retardation, due to expansion and methylation of the CGG sequence at the 5' UTR of the FMR1 gene. Around 90% of affected boys present with attention deficit hyperactivity disorder (ADHD), while this percentage is lower in FXS girls (35-47%). Treatment of these behavioral symptoms is critical for many families.