< J. Craig Venter
source COSMOS+
Agençe France-Presse
4 September 2007
PARIS: The first individual genome ever sequenced – a complete DNA
blueprint of celebrity scientist Craig Venter – has revealed genetic
variation among humans far richer than previously imagined.
Earlier efforts to sequence the human genome used DNA from a group of people; one of whom was also Venter.
Published Tuesday in the free-to-access journal PLoS Biology,
the 2.8 billion contiguous bits of genetic code will also hasten
advances in preventative medicine, said Venter, who is both an author
and the object of the study.
10,000 genomes
Within five years, faster and cheaper sequencing techniques could
produce complete genomes for 10,000 people, laying the foundation for
"an era of individualised genomics," he said. "Once we have those, we
will basically be able to sort out every fundamental question about
nature versus nurture, what's genetic and what's environment."
The findings overturn what had in a few short years become genetic
gospel: that all human beings are, genetically speaking, 99.9
identical. Venter himself trumpeted this idea in 2000 when both his
then biotech firm Celera, and an international consortium of government
and charity scientists simultaneously unveiled the fist complete human
genome.
Both of these earlier efforts were flawed and greatly underestimated
genetic diversity, he and his colleagues now say, because the whole had
been assembled from a hodgepodge of DNA taken from several individuals.
The variations revealed in the new genome, dubbed, "HuRef", go far
beyond previously identified single nucleotide polymorphisms (SNPs),
once thought to be the key to differences in human traits and disease
susceptibility.
SNPs are DNA sequence variations that occur when a single nucleotide
¬– the basic building blocks of DNA, composed in pairs – in the genome
sequence is altered.
Also important, however, are previously overlooked variations in
stretches of genetic code that were once dismissed as useless 'junk
DNA'.
Greater variety
"This dispels the notion we had in 2000 and 2001 that we all have
exactly the same genes in the human population," said Venter, now at
the J. Craig Venter Institute in Rockville, Maryland. "It would have
been very disturbing if the range of characteristics that we see all
came down to a few simple SNP variations."
The new data shows that in an individual genome upwards of 44 per
cent of genes have variable sequences. "This is a number that
geneticists and biologists have been wondering about for 50 to 100
years," commented co-author Stephen Scherer, a geneticist at The
Hospital for Sick Children in Toronto, Canada.
"HuRef" was built on the foundation of Venter's earlier project,
which was already 60 percent composed of his own DNA. But it still took
an additional 10 million dollars and three years to complete.
To spur more efficient technologies, Venter has contributed half a
million US dollars to the 10 million dollar Archon X Prize for
scientists who come up with genome sequencing techniques that are
rapid, accurate and inexpensive.
DNA data protection
Some ethicists have expressed concerns about the possible abuse of
personal health information that may be easily accessible once coding
individual genomes becomes routine.
The study itself raises the issue, if only indirectly: a table
listing some of the traits commonly associated with certain genes
expressions found in Venter's genome reveals more than some people
might care to. A genetic propensity toward Alzheimer's and
cardiovascular disease, for example, prompted Venter to take statins, a
compound thought to help forestall both conditions.
But that same information – or the fact that a person tends towards
traits such tobacco addiction or alcoholism – could be seen in another
light by potential insurers or employers, critics point out.
For Venter, the possible advantages far outweigh such concerns. "We
have all been taught that we should fear this information. We hope to
teach people they should welcome it as a breath of fresh air that gives
them opportunities in their lives," he said.
He did, however, allow for the possibility that anybody's genome information "is relatively easy to get."
source COSMOS+
HemuZ Science
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