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Schizophrenia Gene Discovered

PBS Need to Know - January 30, 2016 对疾病深入理解和治疗的发现。 Discovery could lead to better understanding and treatments.


Alison Stewart, Anchor, PBS Need to Know: Medical researchers have discovered a gene that increases the risk of schizophrenia, a mental illness that affects more than 2 million Americans, sometimes causing delusions and hallucinations. The finding was first reported this week in the scientific journal Nature. Steven McCarroll, an Associate Professor of Genetics at Harvard University, is the study's lead author, and he joins me now from San Francisco. Professor, what was the conventional wisdom about schizophrenia prior to this study, and what was the missing piece of research about that brain disorder that scientists were looking so hard for?
Steven McCarroll, Professor, Harvard University: Well, there have been hundreds of theories about schizophrenia over the decades, and it has been hard to tell which, if any, of those theories was right. What's new here is a very strong genetic link to a very specific gene, and specific versions of that gene, an understanding of what that gene actually does and how it shapes the wiring of the brain.
AS: So, can you walk us through what that gene does?
SM: So, this gene, which is called "C4", is in a neighborhood of the human genome that has hundreds of immune system genes in it. And, that region was previously linked to schizophrenia. What we discovered, though, when we got to the bottom of it, and figured out what gene was propelling this signal, is that it's a gene that, yes, comes from the immune system, but it has this night job in the brain, and that, in fact, it plays a role in instructing the wiring of the brain by causing synapses - the connections between nerve cells - to be eliminated at particular times in development.
AS: Now, this elimination, that's a normal occurrence. What you discovered is that it goes farther than that. It goes haywire?
SM: That's right. All of us go through lots of synapse elimination in our teens and twenties, and it involves the product of this gene. But, what we believe, based on these results, is that that process somehow goes awry, and in particular, it might go into overdrive and result in the elimination of too many synapses.
AS: So, what does this information...how does it help us with the diagnosis of schizophrenia, and with the treatment of schizophrenia?
SM: Drugs for schizophrenia today treat just one of the symptoms of schizophrenia, which is the symptom called "psychosis", which are the hallucinations and delusions. Both are actually just one of many symptoms of schizophrenia, and if you ask most patients what are the symptoms that most bother them, what they will tell you is that it's the agonizing cognitive decline that many of them suffer in their first decade after diagnosis. There are no drugs today that address either the cognitive losses in schizophrenia or the emotional withdrawal or the underlying disease.
AS: So, if I'm understanding what you're saying, the idea is [that] this genetic component is a way to identify the disease before you even have to deal with the symptoms?
SM: Well, the genetics is a way to understand the disease. You know, when we were in school, the genetics that we learned was this very simple genetics - big "B" [and] little "b". It turns out that almost no common diseases actually work that way. They're shaped by the interplay of hundreds of genes, and discovering those genes is a way of telling us what those key biological processes are, so that you can point drug development toward the right biological processes, but testing for any one of those genes in the absence of that complete understanding, doesn't teach you anything. So, we don't recommend that at all. The key thing is going to be understanding the disease well enough to develop new medicines and make the same kinds of progress that we've seen in cancer over the last ten or twenty years...(AS: Steven McCarroll, thank you so much for explaining your work.)...You're welcome!

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