Dramatized in movies like “A Beautiful Mind” and “Through a Glass Darkly,” schizophrenia is a severe, disabling brain disorder that affects about 2.5 million people in the U.S. Usually arising in a person’s late teens or early 20s, it can cause hallucinations, delusions and disordered thinking, among other symptoms.

A research team including Jinong Feng found a possible link between microRNA and schizophrenia. (Photo by Thomas Brown)

Researchers have long held that genetics are at the root of the disease, but its exact cause remains hard to pin down.

Now, City of Hope researchers have shown for the first time that mutations in certain molecules that help control genes may play a role. The findings give researchers new insight into how schizophrenia might arise and offer a potential new way to screen those at risk for it.

MicroRNA, commonly called miRNA, has become known in recent years as a major controller of gene expression. Gene expression is how cells translate the genetic code from DNA into proteins.

MicroRNA directs machinery in the cell to block gene expression. The process occurs as a natural part of cell control.

John J. Rossi, Ph.D., Lidow Family Research Chair and chair of the Department of Molecular Biology, is a renowned expert on miRNA. He led the research along with former City of Hope researcher Steve Sommer, M.D., Ph.D.

“Other research has suggested miRNA is linked to mental disorders,” said Rossi, “so we thought we’d look for mutations in miRNA that might be unique to people with schizophrenia.”

The recent study compares miRNA in 191 healthy people and 193 who had schizophrenia symptoms. The researchers wanted to know if miRNA was mutated in people with schizophrenia.

Their exploration paid off: They found eight extremely rare miRNA mutations in some of the patients with schizophrenia. None of the healthy people had those mutations.

“We were very excited to see the results,” said Jinong Feng, Ph.D., associate research scientist in the Department of Immunology and lead author on the paper. MicroRNA likely is involved in many diseases, “but this is the first strong evidence showing miRNA mutations may contribute to schizophrenia.”