Study of BPN14770 for Teens with Fragile X Syndrome (FXS): This study looks at the safety and effects of a drug called BPN14770 in boys ages 9 to under 18 with Fragile X Syndrome. FXS is a genetic condition affecting brain development. The study has two parts. Part 1 checks how the body absorbs the drug (pharmacokinetics) using a single dose. Part 2 is where participants are split into two groups by chance, one receiving the drug and the other a placebo (a pill with no medicine). Part 2 is "double-blind," meaning neither the participants nor the doctors know who is getting the real drug or placebo to ensure fairness.

• **Study Length:** Participants must commit to a stable medication and therapy routine before and during the study.
• **Participation Requirements:** Must be male, aged 9 to <18, with a confirmed FXS diagnosis.
• **Compensation:** Not mentioned, but participants must attend regular clinic visits.

For Part 1, participants must be able to swallow capsules and weigh at least 75 lbs to take the 50 mg dose. Talk with your doctor to see if this study is right for you.