By cutting in half the activity of a gene, scientists corrected many symptoms of a genetic defect in mice analogous to fragile X syndrome, a leading cause of inherited mental retardation in people.
The research suggests a new target for drug therapy for the condition, which is currently untreatable. However, it remains uncertain whether such drugs would benefit adults who have the disease. And it would take years of clinical trials to show whether drugs could check the disease's progress in infants with the genetic defect.
"I don't think we'd be able to retrospectively correct the derailment of neural development that has occurred over decades" in adults, says lead scientist Mark Bear of the Massachusetts Institute of Technology. However, adults with the disease also suffer from abnormal signaling between nerves. A drug that targets the gene Bear's team studied, which makes a protein called metabotropic glutamate receptor 5 (mGluR5), might be able to restore some mental