Scientists at the University of California, Irvine, have isolated a candidate gene that may be responsible for increasing the risk of schizophrenia and bipolar disorder. This elusive gene encodes for a potassium ion channel that acts like an "off switch" by dampening electrical activity in neurons. It has been known that street drugs such as PCP create schizophrenia-like symptoms by blocking NMDA receptors in neurons. Over-activity of this potassium ion channel blocks the same NMDA receptors, which psychiatrists believe may cause schizophrenia.
The gene sequence contains the trinucleotide CAG repeats thought to cause neurodegenerative diseases such as Huntington's Disease and ataxias. Although specific proteins are still unknown, scientists have implicated the CAG repeats in mental illnesses.
While the gene itself may not predict a person's chances of developing schizophrenia or bipolar disorder, its presence combined with other genetic risk factors and environmental stresses may increase susceptibility to the diseases. UCI researchers and their collaborators found that in schizophrenia patients, there was a significant excess of genes containing the CAG repeat sequences, a possible contributing factor to the molecular origins of the illness. Similar results were found in studies involving bipolar disorder.
Schizophrenia afflicts 60 million persons worldwide and bipolar disorder affects an estimated 60 to 100 million people worldwide. With better understanding of how the CAG repeats relate to mental illnesses, researchers hope that more effective diagnostic tools and therapies may be developed.
|United States Of America||Issued Patent||7,378,496||05/27/2008||1997-307|