Genetic Link to Schizophrenia Discovered
ROBERT SIEGEL, host:
Scientists are reporting a major advance in understanding the genetic underpinnings of schizophrenia. They used a new way of looking for genetic glitches, and they found that people with the disorder tend to have a specific type of change in parts of their genetic code.
NPR's Jon Hamilton has the details.
JON HAMILTON: Schizophrenia tends to run in families, but scientists haven't had much luck finding a genetic explanation for this, until now.
Dr. MARY-CLAIRE KING (Medicine and Genetics, University of Washington): When our results started to come back, I was blown away.
HAMILTON: Mary-Claire King from the University of Washington is part of a team that searched for genetic clues to schizophrenia. They used a technique that wouldn't have been possible just a few years ago.
The team surveyed the complete genomes of 150 people with schizophrenia. They were looking for anything unusual. King says the approach is a bit like what a forest ranger does from a lookout tower.
Dr. KING: Forest ranger scans the horizon and sees off in the distance a flare and says, oh my gosh, that flare signals a fire.
HAMILTON: The flares in this case were mistakes that caused chunks of genetic code to be duplicated or deleted. These errors were scattered all over the genome and they affected different genes in different people. But King says the mutations had one thing in common.
Dr. KING: The genes that were impacted by these mutations were significantly, disproportionately in pathways involved in neural development.
HAMILTON: The mutations were up to four times more common in people with schizophrenia than in healthy people. That's a much stronger correlation than anything uncovered by previous genetic studies.
Jonathan Sebat of Cold Spring Harbor Laboratory says these findings may explain why previous genetic studies didn't find much. Sebat says those studies looked for highly specific changes shared by lots of people.
Dr. JONATHAN SEBAT (Geneticist, Cold Spring Harbor Laboratory): We screen the genome for glitches in the DNA — deletions, duplications, disruptions of genes.
HAMILTON: And they didn't care whether the glitches occurred in just one person or in every person.
Judith Rappoport is at the National Institute of Mental Health.
Dr. JUDITH RAPPOPORT (Chief of the Child Psychiatry Branch, National Institute of Mental Health): This really shifts the understanding of the genetics of schizophrenia, I think, very dramatically.
HAMILTON: The new findings point to what's actually going wrong in the brain of each person with schizophrenia. And there are practical implications, too.
Tom Insel, the director of the National Institute of Mental Health says genetic profiles using the new technique could help identify young people likely to become schizophrenic.
Dr. THOMAS INSEL (Director, National Institute of Mental Health): We diagnose schizophrenia at a very late stage. We diagnose it with psychosis. That's a little bit like diagnosing coronary artery disease with a heart attack. So, what we'd really like to be able to do is to move that forward many, many years so that you would be starting perhaps at age 12 or age 15. And you'd preempt the psychotic event that usually takes place between ages 18 and 24.
HAMILTON: Insel says understanding the genetics of what's going wrong in the brains of people with schizophrenia could also help lead to better treatments.
Dr. INSEL: We know the medications we have now, they help many people to get better but they help very few people to get well. We need to have a generation of medications that truly are going after the core aspects of this disorder in a much more targeted way, kind of smart drugs.
HAMILTON: The findings appear in this week's issue of the journal Science.
Jon Hamilton, NPR News.