Genes linked to schizophrenia identified in ancestral African population

by Tianna Hicklin, Ph.D./National Institutes of Health

At a Glance

  • Researchers found damaging genetic variants linked to schizophrenia in the Xhosa population of South Africa.
  • The findings suggest that though the mutations involved in the disorder are different for each individual, genes with the same functions are involved in all populations.

Schizophrenia is a chronic and severe mental disorder. It affects how a person thinks, feels, and behaves. People with schizophrenia can experience hallucinations, delusions, and disordered thinking. Symptoms can be very disabling.

No single gene causes this disorder. Rather, many different genes are involved, with each patient carrying one or more severe mutations. Most genetic studies of schizophrenia to date have been carried out in people of European and Asian descent. However, African populations harbor the most genetic diversity because most of human evolution occurred in Africa. A relatively small number of people emigrated 50,000 to 100,000 years ago to establish other populations.

To identify and characterize genes related to schizophrenia in an ancestral African population, an international team of researchers sequenced and compared the genomes of more than 1,800 people who identified themselves as Xhosa. Xhosa people live throughout South Africa and are the largest population of the Eastern Cape region. About half the participants had been diagnosed with schizophrenia and half were not.

The research team was led by Drs. Mary-Claire King and Jon M. McClellan at the University of Washington, Dan Stein at the University of Cape Town, South Africa, and Ezra Susser at Columbia University. Their work was funded in part by NIH’s National Institute of Mental Health (NIMH) and National Human Genome Research Institute (NHGRI). Results were published online on January 31, 2020, in Science.

The researchers found that genetic variation, in general, was greater in the Xhosa population compared with the largely non-African genomes that have been studied in the past.

The team then looked for changes in sequence, or mutations, in the exome—the set of genes that code for proteins. They found that people with schizophrenia were more likely to have unique, damaging mutations in their genes.

Those with the disorder were also more likely to have these mutations specifically in genes involved in brain development and in the functioning of synapses, which carry out communication between brain cells.

The team compared these genetic changes in the Xhosa population with those from genetic studies of people with schizophrenia from Sweden. Both studies found mutations in genes related to synaptic function. However, the results from the Xhosa study showed larger effect sizes. The authors suggest that the greater genetic diversity in the African population increases the power of genetic studies to identify genes related to behavioral disorders.

“The presence of only a few DNA variations damaging to synaptic function could have an outsized effect on schizophrenia,” Susser says. “While these variants differ from person to person, we believe they may disrupt neural pathways that elevate the risk for schizophrenia.”

“The genes and pathways identified by this research inform the understanding of schizophrenia for all human populations,” King adds, “and suggest potential mechanisms for the design of more effective treatments.”


Carol graduated from Riverside White Cross School of Nursing in Columbus, Ohio and received her diploma as a registered nurse. She attended Bowling Green State University where she received a Bachelor of Arts Degree in History and Literature. She attended the University of Toledo, College of Nursing, and received a Master’s of Nursing Science Degree as an Educator.

She has traveled extensively, is a photographer, and writes on medical issues. Carol has three children RJ, Katherine, and Stephen – two daughters-in-law; Suzy and Katie – two granddaughters; Isabella Marianna and Zoe Olivia – and one grandson, Alexander Paul. She also shares her life with husband Gordon Duff, many cats, two rescue pups, and two guinea pigs.

Carol’s Archives 2009-2013
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  1. From 1969 to 1995, the entire city of Seattle responded with the opinion that I was schizophrenic, daft, or a bloody liar when I told them that although then in Seattle, my father was working on the WTCs since 1966 and after we spent 3 years in Idaho, they had decided to install the Kellogg fission/fusion demolition system in Manhattan’s WTC twin towers. Now, because of Uncle Gordy and the other researchers with Veterans Today, I have been promoted by the people who I told about the nuke demolition systems BEFORE AND AFTER their use to ‘eccentric’ and no longer a target for ridicule. Now, I just have being an eyewitness of Hillary Clinton’s Colt .38 Foster murder weapon that she was ordered to remove from her purse so I could write down the serial numbers immediately after she illegally purchased it in Seattle during the primary season for the 1984 elections. That and the Fukushima daiicchi sabotage. Once these are contained and gone I will be able to sleep a solid 8 hours a day and ditch the drawbacks of sleeplessness. Sleeplessness eventually yields schizophrenia too. The Kallmann studies and SkidRow drunks’ sleeplessness manifest such breakdowns. Could you tell your husband that if we can get to Seattle, I can still round up several witnesses that will verify THIS TOO. The FBI told us to keep quiet back in 1995.