Inspired in part by Bear's work, pharmaceutical giant Novartis is also testing an mGluR5 antagonist in people with fragile X, as is Neuropharm, a pharmaceutical company based in the United Kingdom. "If we see even a percentage of what we see in the mouse, it will be an important treatment," says Carpenter.

Seaside is also testing a second compound that dampens synaptic activity through a different mechanism--by mimicking the brain's major inhibitory chemical messenger, known as GABA. Previous research has shown that a specific form of an existing drug called Baclofen, which activates GABA receptors and is currently used to treat muscle spasms, can reverse symptoms in mice with a mutation similar to fragile X. The company has just completed a clinical trial of the drug in 60 people with fragile X syndrome and expects results from the study in April. A second study of the drug in people with autism is also underway.

The company is funded almost entirely by an undisclosed family investment of $60 million, with $6 million from the National Institutes of Health. Carpenter says that Seaside has enough funding to take its compounds through clinical testing and approval. "We are prepared to do it ourselves," he says. "But if there is a partnership that allows us to more rapidly advance compounds, then we would embrace that opportunity."

While it's not yet clear whether people with non-fragile X forms of autism would benefit from the same types of drugs, Carpenter and others say those people may share similar molecular problems. For example, genetic studies have linked some cases of autism to mutations in genes controlled by FMRP. Since autism is thought to be a collection of related diseases with different molecular causes, Seaside is looking for protein or DNA biomarkers in the patients in its trials that might predict who would benefit from the molecules being tested.

One theory for the cognitive impairment associated with fragile X, and perhaps with autism in general, is deregulation at the synapse, the connection between two neurons. Our ability to learn is dependent upon the tightly regulated ability to continually change the strength of synapses in response to new information. People with fragile X syndrome and other types of cognitive impairment have immature-looking synapses and inefficient signaling, says Carpenter. That means the brain is "interpreting almost everything that is happening as noise, rather than important information."