style="FONT-SIZE: 12pt; FONT-WEIGHT: bold">APR-2007 style="FONT-WEIGHT: bold">
style="FONT-SIZE: 12pt">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.
style="FONT-SIZE: 12pt">In one of the largest studies yet of human genetic
variability, the scientists tested the DNA of more than 32,000 people in five
countries to pin down spots that harbor genetic risk factors for this
style="FONT-SIZE: 12pt">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
style="FONT-SIZE: 12pt">"We have been for all of the last decade or more looking
under the lamppost to try to find those genes ... and lots of times the
lamplight was not actually where we wanted it," said Dr. Francis Collins,
genetics chief at the National Institutes of Health, a co-author of the research
style="FONT-SIZE: 12pt">This new approach "allows us to light up the whole
street, and look what we find."
style="FONT-SIZE: 12pt">What? 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.
style="FONT-SIZE: 12pt">The work, by three international research teams that
shared their findings, was published online Thursday by the journal Science.
style="FONT-SIZE: 12pt">Also Thursday in the journal Nature Genetics, another
team led by
researchers reported separately finding one of those same new genes - and that,
interestingly, it seems to increase the diabetes risk most in people who aren't
style="FONT-SIZE: 12pt">Next, the researchers will have to figure out just what
those genes do, in hopes they'll point toward new ways to treat or prevent a
disease that affects more than 170 million people worldwide, and rising.
style="FONT-SIZE: 12pt">With Type 2 diabetes, the body gradually loses its
ability to use insulin, a hormone key for turning blood sugar into insulin. It
is a major cause of heart disease, as high blood sugar damages blood vessels,
and leads to kidney failure, blindness and amputations.
style="FONT-SIZE: 12pt">Obesity and lack of exercise are chief risk factors. But
heredity is involved, too: People with an affected parent or sibling are at 3.5
times greater risk of developing diabetes than people from diabetes-free
style="FONT-SIZE: 12pt">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
style="FONT-SIZE: 12pt">The highest-risk variants can increase by 20 percent
someone's odds of developing Type 2 diabetes, the teams reported.
style="FONT-SIZE: 12pt">Among the genes implicated:
style="FONT-SIZE: 12pt">-One that helps pump zinc into insulin-producing
pancreatic cells, raising questions about the metal's role in insulin secretion.
style="FONT-SIZE: 12pt">-A pair previously linked only to certain cancers,
another brand new area for diabetes researchers to probe.
style="FONT-SIZE: 12pt">-A region of chromosome 11 where genes of any sort had
never been described.