Magazine article Science News

New Studies Link Schizophrenia Risk to Thousands of Common Variants: Specific Chromosome Regions May Play Role in the Disease

Magazine article Science News

New Studies Link Schizophrenia Risk to Thousands of Common Variants: Specific Chromosome Regions May Play Role in the Disease

Article excerpt

Large collections of common genetic variants, rather than just the harmful actions of a few key mutations, probably predispose people to schizophrenia, three large genetic studies suggest.

The studies, all published online July 1 in Nature, sifted through genetic data from patients with schizophrenia and people without the disease looking for spelling differences in the sequence of DNA "letters" making up the genome. The studies turned up specific chromosome regions that probably play a role in the disease. Understanding genetic factors, estimated to account for 80 percent of the risk of getting schizophrenia, may ultimately lead to better treatments.

"This is a pretty major breakthrough for us," said Michael O'Donovan of Cardiff University's School of Medicine in Wales at a July 1 press briefing. O'Donovan, who coauthored one of the studies as part of the International Schizophrenia Consortium, says a person with schizophrenia probably has hundreds or thousands of risk-increasing variants.

Using a method called genome-wide association, each of the three studies compared DNA samples from several thousand people diagnosed with schizophrenia with samples from thousands of others, some healthy and some with other diseases. Association studies are designed to find single letter differences, called SNPs, at many points along the DNA. Variants popping up more frequently in the schizophrenia patients' DNA are presumed to be markers of regions of the genome that contribute to the disease.

Many thousands of common DNA variants (those found in about 5 percent of the total population) turned up more often in people with schizophrenia, the studies found. "This is the first empirical DNA-based evidence" for many small genetic effects adding up to schizophrenia, says Pamela Sklar of Massachusetts General Hospital and Harvard University, who coauthored the consortium study. …

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