New scientific evidence further confirming a genetic basis to schizophrenia was discovered by a UMDNJ-New Jersey Medical School researcher, who identified a specific chromosome that appears to be linked to development of the psychiatric disorder affecting two to three million people in the United States. The findings are reported in the April 28 issue of Science.

    Linda Brzustowicz, MD, assistant professor of psychiatry, said the chromosome 1 region is suspected in causing schizophrenia in the 22 families being studied and was identified after a genome-wide search of family relatives who had the disease. Brzustowicz and four collaborating researchers from the University of Toronto and the University of British Columbia conducted the research. Brzustowicz is principal investigator of the gene mapping portion of the study. She is also an assistant professor of neuroscience at Rutgers-Newark.

    "We have identified a major gene effect conferring susceptibility to schizophrenia," Brzustowicz said. "This goes a long way to demonstrating a very strong genetic component to the disorder, at least in the family groups studied."

    The Canadian families - of Celtic and German descent - were selected for the study because multiple relatives had been diagnosed with some form of schizophrenia. Schizophrenia has long been suspected of having both environmental and genetic causes. Debate has raged about which holds the most influence.

    While Brzustowicz's research leaves that question unanswered, it appears to confirm a complex genetic basis for the disease since it also identifies a second region, on chromosome 13, that is linked to schizophrenia in the same set of families. Brzustowicz's studies confirmed the role of chromosome 13 that was previously discovered in an unrelated set of families.

    Brzustowicz's study is also notable for the confidence level of the finding. Most genetic studies have either been inconclusive or only weakly suggest a linkage. "This study provides evidence for a linkage that is at least 100 times

stronger than any other study published to date," she noted. Researchers suspect several different chromosome groups and multiple genes are involved in susceptibility to schizophrenia.

    Brzustowicz said the next step will be to pinpoint what gene on chromosome 1 causes schizophrenia. She said they know the chromosomal "neighborhood" of the gene linked to schizophrenia, but still must find its specific "address." Following isolation of the gene and identification of the specific mutation involved in schizophrenia, the researchers will search for similar mutations in individuals with schizophrenia from other ethnic groups to determine the relevance of this finding to individuals worldwide.

    While drugs to better control schizophrenia based on this finding appear at least a decade away, Brzustowicz said that a blood-based screening test for genetic susceptibility to schizophrenia might be possible in a year or less. She warned, however, that without knowing how other genes and environmental factors affect disease progression, identifying susceptible individuals based on one gene might not be that helpful.

    "This does hold out the promise that someday we may be able to do screening for schizophrenia and possibly approach it from a preventive perspective," she added. She said that people with a family history of the disease appear to be taking solace in the news that a genetic basis for schizophrenia is becoming clearer. A diagnostic test for schizophrenia could allow for earlier intervention with traditional drug therapies and may lessen the severity of the disease.

    The study examined DNA from 288 participants. Family members diagnosed with schizophrenia spanned three generations in 27 percent of families, and three or more generations in 45 percent of families. Funding was provided by the National Institute of Mental Health, Medical Research Council of Canada, EJLB Foundation, Ontario Mental Health Foundation, Bill Jeffries Schizophrenia Endowment Fund, the Nova Scotia Schizophrenia Society, and the Ian Douglas Bebensee Foundation.