The same problem hasn't been as visible in other types of autism, but many believe the phenomenon is somewhat similar.
The drug was deemed successful in mice and is now being tested in children and adults. In small, early studies, the drug made a striking difference in small groups of Fragile X children, causing hermit-like youngsters to start hanging out in the kitchen to chat with their mothers, said Dr. Paul Wang, Seaside's vice president of clinical development.
Now it is being tried in a preliminary study of about 150 children with a range of other autism disorders, including Asperger's. The results are expected to be presented at a scientific conference in the next year.
"It's going to be an exciting time, we hope," when those results come in, said Dawson, from Autism Speaks.
But even genetics enthusiasts acknowledge that genes are only part of the answer. Studies of identical twins have shown that autism can occur in one and not the other, meaning something outside a child's DNA is triggering the disorder in many cases. Some cases may be entirely due to other causes, Dawson said.
That broad "other" category means "environmental" influences — not necessarily chemicals, but a grab bag of outside factors that include things like the age of the father at conception and illnesses and medications the mother had while pregnant.
For years, the best-known environmental theory involved childhood vaccines, prompted by a flawed 1998 British study that has been thoroughly discredited. Dozens of later studies have found no link between vaccines and autism.
But there are other possible candidates. In all cases, these are "association" studies — they don't prove cause and effect. They merely find connections between certain factors and autism. And sometimes these conclusions can be skewed by other things researchers failed to account for. Some study results expected within a year:
— Hertz-Picciotto's study of 1,600 children in Northern California is comparing autistic children, youngsters with other developmental disabilities, and those who have no such diagnoses. Some results have been released already, including the recent finding that suggests a link between autism and a mother's obesity. An earlier part of the study found that children born to mothers living less than two blocks from a freeway were twice as likely to have autism — presumably because of auto exhaust and air pollution, the researchers speculated.
—A Centers for Disease Control and Prevention study involves 2,700 families nationwide. The researchers are interviewing parents and poring over medical records to look for common threads among autistic families, as well as doing genetics tests and checking hair samples for mercury. Much of the focus is on illnesses, medications, nutritional deficiencies or other problems during pregnancy.
—A study by Pennsylvania researchers involves 1,700 families in various regions of the country. Scientists are doing brain-imaging to look for changes over time in the brains of infants who have an older autistic sibling.
—A large Scandinavian study is examining patient registries in six countries for prenatal risk factors.
As study findings are reported, researchers are hoping to see repetition — confirmation, that is — that certain factors are playing significant roles.
Even so, scientists are still casting nets.
Said Coleen Boyle, a CDC official overseeing research into children's developmental disabilities: "We're at the infancy of just understanding how these factors relate to autism."
CDC study under way: http://www.cdc.gov/ncbddd/autism/seed.html
Northern California study: http://beincharge.ucdavis.edu
Pennsylvania researchers' study: http://www.earlistudy.org
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.