April 12, 2004

Causes of Schizophrenia

Surprises Found In Gene Variation Associated With Schizophrenia

Approximately 2 percent of Caucasians have a gene segment variation that can cause a certain form of schizophrenia. Most people with the variation, known as a polymorphism, do not have the disease. A University of Iowa Health Care study reveals a good prognosis for people who do have this form of schizophrenia. The team also found that this polymorphism is associated with overall benefits for human survival, and the initial mutation occurred in a single common ancestor about 100,000 years ago.

The findings have implications for finding better ways to treat this particular type of schizophrenia and possibly augmenting the positive influences of the polymorphism on human survival. The study results appeared in the February 11 online issue of the American Journal of Medical Genetics.

"We knew the gene causes a specific form of schizophrenia, but we didn't know that the type was associated with a good prognosis and marked by absence of negative symptoms," Philibert said. "Most individuals with this positive symptom schizophrenia are able to function in society and hold down jobs."

He added that the gene cannot by itself cause schizophrenia but must interact with other genes and environmental factors to result in illness. In addition to sometimes leading to schizophrenia, it also can cause hypothyroidism or obesity.

"It is critical to understand those interactions. If we can modulate them, we may be able to block the ill effects of this gene and keep the beneficial aspects," Philibert said.

HOPA stands for Human Opposite Paired Element. It was first isolated in 1994, when Philibert worked at the NIH.

"There are at least 25 genes in the gene complex in which HOPA participates. Several of the genes are known to be involved with other forms of human illness. Because this polymorphism is relatively common and because we have human models of it, it can be used as a paradigm to understand those other gene defects," Philibert added.


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