With Schizophrenia Genes Identified, What’s Next?

At the Ninth International Congress on Schizophrenia Research, held recently in Colorado Springs, Colo., an award for outstanding research was bestowed on one of the some 1,000 schizophrenia scientists present. It was Daniel Weinberger, M.D., head of the Clinical Brain Disorders Branch of the National Institute of Mental Health. He received the award for his work on the genetics of schizophrenia.

Six schizophrenia susceptibility genes, in fact, have now been identified, and each has been confirmed in at least four studies, Weinberger announced. The question, of course, is how often does a finding about a schizophrenia susceptibility gene have to be replicated to truly prove that it is a susceptibility gene?

“I don’t think there is any answer to this question,” he admitted. But the evidence is substantial enough at this point to constitute very firm evidence, he believes.

The genes are on chromosomes 1, 6, 7, 8, 13, and 22, he reported. The most is known about the susceptibility gene on chromosome 22. It is a variant of a gene called the COMT gene. The variant is known to influence the transmission of the neurotransmitter dopamine in the prefrontal cortex of the brain and to impair working memory.

Another of the susceptibility genes that has been identified, he continued, is a variant of a gene called GRMC. This variant is known to impair glutamate transmission in the prefrontal cortex of the brain, as well as working memory and verbal fluency.

The third schizophrenia susceptibility gene that has been identified, he pointed out, is a variant of a gene called dysbindin. The variant is known to be abundant throughout the brain and to impact IQ and the speed of information processing.

Now that schizophrenia susceptibility genes “are no longer not found,” Weinberger said, “the challenge will be to learn more about their influence on brain physiology.”

The genes, he added, will also offer a way to identify people at risk for schizophrenia and to serve as targets for new types of schizophrenia drugs. ▪