Progress in identifying the genetic roots of autism

Scientists say that roughly 20% of autism cases can be linked to known genetic abnormalities, and may more may be discovered. Pinpointing a genetic explanation can help predict whether siblings are likely to have the disorder and even point to new, targeted  treatments. Last week, for example, researchers reported that an experimental drug, arbaclofen, reduced social withdrawal and challenging behaviors in children and adults with Fragile X syndrome, the single most common genetic cause of autism.