Research published in the American Journal of Psychiatry shows that schizophrenia is not a single genetic disease, but in fact a class of diseases with variable symptoms. Schizophrenia is known to be passed in families, implying genetic origins, but no single mutation has ever been shown to cause symptoms to emerge.
It turns out, that's because different "orchestras" of mutations working together cause a range disorders that until now had been understood as a single disease. These results emerged from a new approach to studying the illness. Scientists examined the DNA of 4,200 people with schizophrenia and 3,800 healthy controls, looking for places in the genome where a single nucleotide, the smallest unit of data in DNA, had mutated. They found that none of the individual mutations produce significant risk for the disorder on their own. However, particular clusters of mutations create risk of developing schizophrenia and different symptoms. Eight have been found so far, and they expect to uncover more.