Studies Decode Genetic Risk for Type 2 Diabetes Four new separate studies announce the discovery of three regions of human DNA that contain clear genetic risk factors for Type 2 diabetes. The study is among the first to apply a suite of genomic resources to common diseases.
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Studies Decode Genetic Risk for Type 2 Diabetes

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Studies Decode Genetic Risk for Type 2 Diabetes

Studies Decode Genetic Risk for Type 2 Diabetes

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From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.


And I'm Robert Siegel.

Four scientific papers are being released today that expand scientists' understanding of the genetics of the most common form of diabetes. Researchers have known for years that many genes had to be involved in the disease but since diet and environment also play an important role in causing the illness, finding the specific genes has been a monumental task.

And joining us to talk about the new results is NPR's science correspondent, Joe Palca. Oh, Joe, first of all what form of diabetes are we talking about here.

JOE PALCA: Well, this study deals with type 2 diabetes, which is the kind of diabetes that usually comes on later in life. It's when your cells stop producing enough insulin. The beta cells in your pancreas stop producing enough insulin or the cells in your body don't respond appropriately to the insulin that you are producing. This is to be contrasted with type 1 diabetes which is usually, you know, your body attacks the insulin producing cells and that usually occurs in childhood.

SIEGEL: And now how did scientists know that there was more than one gene involved?

PALCA: Well, when there is a single gene involved it's easy to see how a particular disease tracks in a family. You know, one parent has it, a child has it, child is - it tends to fall very closely. In this case, it didn't follow so closely. It is more common in families but it wasn't clearly going from one generation to the next and so they knew just easily by a simple look. They knew there had to be more than one involved.

SIEGEL: You know, there's more than one, but then how do you go about trying to figure out which are those multiple genes?

PALCA: Well, this is where it gets really tricky. And in a way, it's taken in a human genome projects and some other tools known as the SNiP consortium and the haplotype map. Basically, what happened is you need to be able to see where variations are. The human genome project gave the human genome as it was in a very generic sense. But each of us have slightly different versions.

So you want to be able to compare the Robert Siegel genome and the Joe Palca genome and a lot of other genomes then you want to see well, do you have one disease or another in this case diabetes. And so you look for the variations that track with the particular illness. And so you look at tens of thousands of people and that's how they came up with these three new genes by looking at lots of different people.

SIEGEL: Isn't there a catch here though that since this is the form of diabetes that appears later in life, you could be finding people who would be genetically disposed but haven't yet experienced symptoms of the disease?

PALCA: Right. And that's another reason it's harder to find. I mean because you have to wait until people show up with the disease before you can know who you want to find to look for. But the interesting thing about the genes that they did find is that they had no idea this were associated with diabetes at all. I mean they didn't go in with any specific preconceived notion about what genes they're going to find. They just said let's see what is associated.

It's just strictly association. Then they look at them, (Unintelligible) - we didn't even know that was involved. In fact, I was talking with David Altshuler of the Broad Institute, who's the author of one of the papers. And one of the genes they found isn't really what they think of or what they typically described as a gene at all.

Mr. DAVID ALTSHULER (Broad Institute): When we look at this diabetes study, one of the most interesting finding is a region on the ninth chromosome where there's a clear relationship between inheriting a different sequence here and diabetes. There's no gene anywhere nearby. A hundred thousand letters needed direction, it would have been called junk DNA. And yet it's not junk DNA.

SIEGEL: So this part of the genome that was thought to be responsible for nothing turns out to be responsible in part with the disease?

PALCA: Exactly. And it just shows - I mean - it's sort of like it's the Huber's(ph) of all now we have all the understanding. Of course, we don't. I mean the concept is genes make proteins but this is something that's inherited like a gene. But it doesn't actually make a protein. So now the trick is to find out what is it doing? I mean why does a variation in this particular region of DNA make a difference?

SIEGEL: Yeah, we're talking about papers reporting basic science, basic research. When might agree to the stage of actually being a medical therapy that might prevent diabetes.

PALCA: You know, this is the question that scientists always loved to answer and dread at the same time. This kind of research brings us closer because if you don't understand how something works at all it's going to be hard to figure out how to fix it. So now they think they're on to some new ways and new kinds of understanding of how the disease works. That said these aren't big players. So it may be that these particular genes don't turn out to be that important and yet one of the big pharmaceutical companies, Norvatis, is a participant in it and a sponsor of some of this research. And so you think well, if they're involved they must see some promise for this at least down the line.

SIEGEL: One last point, I understand that these four papers were actually originally supposed to be published next week but publication was moved up. Is this a race to get out there with the new diabetes news?

PALCA: Well, yeah, in one sense, I guess. That's exactly what this is. One of the papers from a group called deCODE which is a company in Iceland was publishing "Nature of Genetics(ph)" and they moved their paper up and then some other groups and science who were international collaborators moved their paper up and so it all came together and they rushed it into print today.

SIEGEL: I wanted to say you heard it first.

PALCA: Right.

SIEGEL: Joe Palca, thank you very much.

PALCA: You're welcome.

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