(HealthDay News) – A γ-aminobutyric acid type B (GABAB) agonist, STX209 (Arbaclofen), can significantly improve social function in patients with fragile X syndrome, according to a study published in the Sept 19 issue of Science Translational Medicine.

Elizabeth M. Berry-Kravis, MD, PhD, from the Rush University Medical Center in Chicago, and colleagues randomly assigned 63 patients (55 male; 6–39 years old) with fragile X syndrome with a full mutation in the FMR1 gene on the X chromosome (>200 CGG triplet repeats) to placebo or STX209 in a crossover study.

The researchers found that STX209 had no significant effect on irritability as measured with the Aberrant Behavior Checklist (ABC)-Irritability subscale. There was improvement noted on the visual analog scale rating of parent-nominated problem behaviors, with positive trends in numerous global measures. Using the newly validated ABC-Social Avoidance Scale, there was a significant beneficial treatment effect. Significant improvement in social function was observed by several additional assessments in a subgroup of 27 patients with more severe social impairment. The drug was well tolerated, with sedation and headache as the most common side effects (8% incidence).

“This study will help to signal the beginning of a new era of targeted treatments for genetic disorders that have historically been regarded as beyond the reach of pharmacotherapy,” Berry-Kravis said in a statement. “It will be a model for treatment of autism, intellectual disability, and developmental brain disorders based on understanding of dysfunction in brain pathways, as opposed to empiric treatment of symptoms. We hope mechanistically-based treatments like STX209 ultimately will be shown to improve cognitive functioning in longer-term trials.”

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Several authors are employees of or disclosed financial ties to Seaside Therapeutics, which funded the study and manufactures STX209.

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