[Paleopsych] Scientists Reveal Map of Human Genetic Variation and Warn That It Does Not Reflect Racial Differences
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Wed Apr 13 17:51:39 UTC 2005
Scientists Reveal Map of Human Genetic Variation and Warn That It Does Not
Reflect Racial Differences
News bulletin from the Chronicle of Higher Education, 5.2.18
[We should watch for cutbacks in these warnings.]
By LILA GUTERMAN
Scientists from a company in California revealed on Thursday a map of
genetic variation across populations. Hailed as possibly a significant
step toward an era of personalized medicine, the map also raised
concerns that it would be publicly misunderstood as proving a genetic
basis for race.
The scientists, from the genetics company Perlegen Sciences, announced
their findings at the annual meeting here of the American Association
for the Advancement of Science. Their results will also be published
in today's issue of the journal Science.
The map's importance derives from the fact that many diseases and
medicines affect people differently, at least in part because of
variation in genes. But single genetic differences often do not
explain the differences in responses to diseases or drugs.
David R. Cox, Perlegen's chief scientific officer, said on Thursday
that looking simultaneously at multiple genetic differences among
people could produce a sort of "bar code" to predict the
susceptibility of a given person to cancer, for instance, or whether a
drug would lower an individual's blood pressure.
He and his colleagues looked at 1.6 million sites in the human genome
where differences in DNA are common among people. At those sites,
people have one of two chemical letters. The scientists analyzed which
letter occurred at each of the 1.6 million sites in the DNA of 71
Americans -- 23 of African ancestry, 24 of Asian ancestry, and 24 of
European ancestry. They found that, for most of the sites, all three
groups bore both chemical spellings, but often in differing
The scientists plan to use their results to look for different genetic
spellings associated with susceptibility to various diseases or
responses to drugs. Scientists would do that by checking for
differences between smokers with cancer and those without, for
instance, or between people whose blood pressure goes down after
taking a drug and those whose blood pressure stays the same. The
company has made its data publicly available on its Web site. The
data are also available on the California Institute for
Telecommunications and Information Technology's Web site.
In an essay that will be published with the Perlegen paper, two
scholars -- David Altshuler, of the Broad Institute of Harvard
University and Massachusetts Institute of Technology, and Andrew G.
Clark, of Cornell University -- write that the company's data are "of
exceptionally high accuracy."
For about 18 percent of the sites, however, only one of the ethnic
groups bore two spellings; the other groups had only one spelling. But
Dr. Cox emphasized that such a pattern does not mean the genetic
variations underlie race.
"Trying to use DNA to define race is like putting a square peg in a
round hole," he said.
In an interview, Troy Duster, a professor of sociology at New York
University, agreed. He said he was concerned that studies like
Perlegen's could "give a kind of imprimatur of scientific authority"
to the notion that race is biologically determined.
He pointed out that the 71 individuals do not represent all of the
genetic diversity of their races, and that genetic differences would
exist between any two small groups of people.
"If you took a group of people from the East Coast and the West Coast
... you'd find differences," he told The Chronicle. "You wouldn't
conclude there were genetic differences between the two coasts. But
with race or ethnicity, people are preprogrammed at a cognitive level
to think in terms of these genetic categories."
Mr. Duster writes, in another essay in Science, that studies like
Perlegen's "should always attach a caveat or warning label like this:
'[Genetic] frequencies vary between any selected human groups -- to
assume that those variations reflect 'racial categories' is
More studies are sure to appear shortly. An international group of
government-backed scientists is working on a similar project, called
the International Haplotype Map Project (The Chronicle, October
30, 2002), and in recent months, the Perlegen scientists have joined
forces with them.
Background article from The Chronicle:
* International Team Begins New Map of Human Genome, Seeking
Variations Within Large Blocks of DNA (10/30/2002)
45. mailto:lila.guterman at chronicle.com
E-mail me if you have problems getting the referenced articles.
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