Single Gene Defect Could Drive Some Mental Illness

Study suggests one mutation can give rise to conditions like schizophrenia

WEDNESDAY, Feb. 16, 2005 (HealthDay News) -- A subtle imbalance in the activity of a single gene may be responsible for the multiple symptoms experienced by people with complex developmental disorders like schizophrenia, new research suggests.

Symptoms of schizophrenia include paranoia, delusions, antisocial behavior and hallucinations. Previous research suggested that a combination of genetics, prenatal trauma, viral infection and early life experience may predispose people to the illness.

However, findings from a Dutch study published in the Feb. 17 issue of the journal Neuron suggest an imbalance in just one gene could turn out to be a major player in seemingly complex conditions like schizophrenia.

Researchers at the Nijmegen Center for Molecular Life Sciences and elsewhere analyzed the activity of thousands of genes in the brains of two groups of rats bred to be either resistant or susceptible to the drug apomorphine.

Previous research shows that apomorphine-susceptible rats differ in key behavioral and biochemical ways from normal rats, in much the same way that people with mental illness can differ from healthy individuals.

Despite their exhaustive search, the researchers found only a single genetic difference between the two groups of rats: Activity levels of the Aph-1b gene tended to be lower in the apomorphine-susceptible rats. These rats had reduced activity of a single protein called g-secretase, which is produced by the Aph-1b gene and plays a role in regulating many of the processes in the developing brain.

"Thus, a subtle imbalance in the expression of a single gene product" could have downstream effects that give rise to complex neurological illnesses, the study authors conclude.

More information

The U.S. National Institute of Mental Health has more about schizophrenia.

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