This Phase 2 proof-of-concept study is a double-blind, randomized, placebo-controlled,
crossover study to investigate ganaxolone treatment in children with fragile x syndrome
(FXS). Up to 60 subjects (ages 6-17 yrs) will be randomized to receive either ganaxolone or
placebo for 6 weeks and then cross over to the opposite treatment for another 6 weeks. The
aim of the study is assess the safety, tolerability and efficacy of ganaxolone for treatment
of anxiety and attention in subjects with FXS. The hypothesis is that ganaxolone treatment
compared to placebo will improve anxiety and attention as measured by the several
neuropsychological and psychometric tests.