A drug called arbaclofen has shown potential for relieving symptoms of fragile X syndrome — a genetic disease that causes intellectual disability and autism — according to a clinical and an animal study published back-to-back.

Fragile X syndrome is caused by a faulty gene, which leads to excessive protein synthesis at neuronal connections, or synapses, in the brain, and to exaggerated excitatory neurotransmission. Two teams led by scientists from Seaside Therapeutics in Cambridge, Massachusetts, investigated whether arbaclofen — which promotes inhibitory neurotransmission by activating GABAb receptors — could mitigate symptoms.

Paul Wang and his colleagues ran a placebo-controlled clinical trial in 63 people with fragile X. They found no effect on irritability, but social function improved in 27 people who had severe social impairment.

In a study of mice with the condition, Aileen Healy and her colleagues found that the drug corrected the excessive protein synthesis and associated synaptic abnormalities.

Sci. Transl. Med. 4, 152ra127; 152ra128 (2012) ;