Scientists who launched an all-points search for manic-depression genes say they’ve found five possible hideouts.
Further work might reveal the genes themselves, a step toward finding better treatments for a condition that strikes 1 percent to 2 percent of Americans at some point in their lives.
Scientists have strong evidence that genes play a role in making people vulnerable to the disorder, but so far no gene has been identified.
The new work was reported in the April issue of the journal Nature Genetics by three scientific teams working independently.
“While still provisional, these studies taken together signal real progress,” said Dr. Steven Hyman, director of the National Institute of Mental Health.
In a commentary accompanying the work, Stanford University gene experts Neil Risch and David Botstein cautioned that the work must be considered preliminary. The search for manic-depression genes has been marked by leads that did not pan out, they noted.
To do the studies, researchers studied families that have an inherited tendency toward the illness. They tracked hundreds of markers, which are readily identified bits of DNA, throughout all the human chromosomes. These studies gave evidence that manic-depression genes lie near certain markers.
One team found evidence for manic-depression genes on chromosomes 6, 13 and 15 in Old Order Amish families from Lancaster County, Pa. The group included neurologist Dr. Edward Ginns of the mental health institute, Janice Egeland of the University of Miami, and others.
The research suggests that the disease comes from the interaction of genes in the Amish families, the researchers said. Other sets of genes may be at work in other groups, they said.