DNA mutations may trigger schizophrenia

From Bloomberg news:

Spontaneous defects in DNA may trigger schizophrenia, according to research that bolsters results of smaller studies aimed at finding the genetic causes of the disabling mental disorder.

In the largest study of its kind, international research teams found evidence that schizophrenia can be caused when genes are duplicated or deleted in an often random process that isn't inherited from parents, according to reports published July 30 in the journals Nature and Nature Genetics.

Scientists found that people with schizophrenia are more than 10 times as likely to have these rare chromosomal alterations as people who don't have the illness.

While the findings fill in parts of the puzzle of the disease, they also suggest it may be caused by a complex set of genetic flaws, which could complicate the search for effective treatments.

"This is just the beginning,'' Pamela Sklar, a geneticist and psychiatrist at Massachusetts General Hospital in Boston, who led one of the research teams, said yesterday in a conference call. "It only explains a tiny fraction of why people might develop schizophrenia.''

Family history is a strong risk factor for schizophrenia, with about 40 percent of patients having a close relative with the disease. Schizophrenia, like some other illnesses, is believed by scientists to result from a combination of both genetic and environmental causes.

In one of the studies, researchers examined data from nearly 3,400 schizophrenia patients and about 3,200 other people in five countries. Researchers looked at a relatively rare type of change in the human genetic code in which people have a large stretch of DNA that is missing or duplicated. Scientists have been linking these "copy number variations,'' or CNVs, to more illnesses, including autism and mental retardation.

Researchers found that those with the alterations were 10 times more likely to have schizophrenia and that two specific parts of the genome, when altered, greatly increased the risk of developing the disease.