NEWBURYPORT - Scientists funded in part by a Newburyport research foundation announced that they have identified a brain chemical that could reverse the effects of fragile X syndrome, a genetic disorder that can cause autism and mental retardation.

The findings, published in the Proceedings of the National Academy of Sciences by an international team of researchers led by MIT Nobel laureate Susumu Tonegawa, could offer hope for those who suffer from fragile X syndrome, of whom there are an estimated 100,000 in the United States alone.

The research was partially sponsored by the Newburyport-based FRAXA Research Foundation, which was founded in 1994 by West Newbury residents Michael Tranfaglia and Katie Clapp after they learned that their son Andy had the disorder.

"We looked around at the state of the research on fragile X and what we found was really discouraging," Tranfaglia said. "There just wasn't a lot going on."

So the couple began trying to jump-start the research process by putting scientists in touch with each other and raising money to fund research projects. In the last 13 years, they have raised nearly $12 million, some of it in large chunks but most of it in small increments from the families affected by fragile X syndrome. Both Clapp and Tranfaglia devote most of their time to the foundation, they said.

Now 18, Andy goes to a public school in Haverhill that is well suited to his needs. But Clapp said she is concerned about what will happen in a few years when he becomes too old to attend the school. Andy has seizures and an IQ of about 50, and he suffers from the anxiety, obsessiveness and learning problems that are common among those with fragile X, his parents said.

The Tonegawa team's research offers some new hope, Clapp said.

According to a press release, people with fragile X can't produce a protein known as FMRP in their brains. The spines at the end of their nerve cells grow longer, thinner and in greater numbers than they do in healthy people. Scientists tried in recent years to find a way to deliver FMRP or a substitute to brain cells, but with little success because the target is so specific.

Researchers in Tonegawa's lab found another way to approach the problem. They noticed that when a different enzyme known as p21-activated kinase, or PAK, is inhibited, the spines on nerve endings grow thicker, shorter and more sparsely. The scientists thought that perhaps by adjusting the levels of PAK, they could make up for the absence of FMRP in the brains of those with fragile X syndrome.

To test the theory, the scientists cross-bred two strains of mice - one with fragile X syndrome and one in which PAK levels plummet beginning in adolescence. The results were dramatic. When the cross-bred mice had their PAK inhibited, the electrical behavior of their brains as well as their outward behavior returned to normal.

The next step is to work with pharmaceutical companies to identify a drug that inhibits PAK, Tranfaglia said. In a best-case scenario, human trials could begin within a couple of years.

Clapp said she is especially encouraged by the PAK research because it suggests that unhealthy brains can be repaired well after their developmental period.

"This is really promising news because it suggests that the brain can be restored to something near normal even very late in the game," she said. "I'm hopeful that our son Andy might benefit from this research himself."