New information on the genetics of Type 2 diabetes

Although I've chosen "genetic testing" as the topic for this blog entry, none of the new "genes" reported in the latest news have had genetic tests developed for them yet. So, you cannot run out and get tested for these genes yet.

Today, Associated Press medical writer Lauran Neergaard wrote an article, New diabetes risk factors found, that is hitting all the newspapers and online services. The author writes:

Scientists have found clusters of new gene variants that raise the risk of Type 2 diabetes — and how the researchers did it is as important as what they found.

So, what did they find and what is the technique that is so important?

First, their findings:

Four previously unknown gene variants that can increase people's risk of Type 2 diabetes, and confirmation that six other genes play a role, too. The highest-risk variants can increase by 20 percent someone's odds of developing Type 2 diabetes. Among the genes implicated:

  • One that helps pump zinc into insulin-producing pancreatic cells, raising questions about the metal's role in insulin secretion.
  • A pair previously linked only to certain cancers, another brand new area for diabetes researchers to probe.
  • A region of chromosome 11 where genes of any sort had never been described.

Second, how did they do it?

The new work scanned DNA to find patterns of small gene variations known as SNPs (pronounced "snips") more common in diabetics. SNPs can serve as signposts for tracing disease-promoting genes. To be certain the implicated SNPs were involved, the researchers then checked for them in still more volunteers, ultimately testing DNA from 32,500 people in Britain, Finland, Poland, Sweden and the U.S.

This type of research — called a "genome-wide association" study — promises to usher in a new era of genetics. Most breakthroughs so far have come from finding a mutation in a single gene that causes illness. But some of the world's most common killers, such as heart disease and diabetes, are caused by complex interactions among numerous genes and modern lifestyles — and teasing out the genetic culprits until now has been almost impossible.

You do not need to know what SNPs are to understand the research, but you might want to know about a word not used in the article--genomics. Genomics is the study of an organism's entire set of genetic material. Genomic studies are typically conducted with samples from more than one person, mouse, virus, etc., although it is possible to map the genome of a single individual. In this search for DNA variations possibly associated with Type 2 diabetes, 32,500 different sets of DNA were involved.

One other bit of information that might be helpful to you. Type 2 diabetes is the variety of diabetes initially thought to result strictly from obesity and lack of exercise. People generally develop this type as adults. Type 1 diabetes, also known as juvenile diabetes, typically develops much earlier. We've known for some time that genetics plays a factor in the potential for developing Type 2 diabetes. Now we know that at least 10 genes may be involved. Therefore, there is no single "gene" for diabetes; there are many that may play a part.

You can access the full AP article, but the Science and Nature articles both require subscriptions.

Marie Godfrey, PhD

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