Previous searches for schizophrenia-related genes have identified only weak connections, but using a new method to analyze genetic variations in families, scientists at Johns Hopkins today report on rare mutations that they say “team up” to cause the disease.

The scientists also show it’s likely that individual cases are caused in part by different combinations of genetic variants.

“These results support the idea that there’s no single genetic recipe for schizophrenia, but that a buildup of mutations in a pathway related to the disease—like neuregulin signaling—can be the culprit,” Johns Hopkins’ Dimitrios Avramopoulos, M.D., Ph.D., associate professor of psychiatry at the McKusick-Nathans Institute of Genetic Medicine, said in a statement. “The results are also evidence for the current theory that schizophrenia isn’t a single disease at all, but a suite of related disorders.”

Dr. Avramopoulos and his colleagues first analyzed previously obtained data on 123 families with at least two affected members. Then, finding support for their initial pathway hypothesis, the scientists sequenced genes associated with neuregulin signaling in 48 patients. Writing today in Translational Psychiatry, the researchers today report that some families showed multiple neuregulin signaling-associated variants while others had none, and that patients with multiple such variants experienced more hallucinations—though less impairment—than those with fewer or no such variants.

Now, Dr. Avramopoulos et al., intend to drill down into the functional roles of the neuregulin signaling-associated variants they’ve identified in an effort to elucidate how they might contribute to schizophrenia.

The scientists also suggest the results point to the power of their analytical approach, which could also be applied to other common diseases that appear to have complex genetic roots, such as diabetes and heart disease.

The study, “Multiple variants aggregate in the neuregulin signaling pathway in a subset of schizophrenia patients,” was published May 28 in Translational Psychiatry.

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