[Didn't the genome project come in lower than previous estimates?
Blast, can't find the number in Kauffman's book!]
Tally of Human Genes Challenged
Estimate May Be Higher Than Genome Project Predicted, Study Says
By Terence Chea
Washington Post Staff Writer
Friday, August 24, 2001; Page A10
Scientists are challenging one of the most widely reported findings to
come out of the first detailed analysis of the human genome: that a
relatively small number of genes are needed to make a person.
When researchers at Rockville-based Celera Genomics Corp. and the
publicly funded Human Genome Project published their work in
scientific journals in February, each group estimated the human
genetic code was made up of about 30,000 genes, only about twice that
of a worm or fly.
Now a study published in today's journal Cell argues that number is
too low. Scientists at the Novartis Research Foundation's Genomics
Institute in San Diego compared the two genome sequences and found
that almost half the genes each group predicted did not overlap with
the other group's genes.
If added together, they concluded, the overall tally of genes could be
much higher than either group predicted.
"It underscores that Phase 2 of the genome project, which is finding
all the genes, is still a work in progress," said Michael P. Cooke,
coauthor of the article. "It will be a few years before we have a
complete list of the genes that control human biology."
Scientists want to identify all the human genes to understand what
causes disease and develop medicines to treat them. But only about 1
percent of the genome's approximately 3 billion chemical units make up
genes, and the process of identifying those genes is far from an exact
science.
Francis Collins, director of the National Human Genome Institute in
Bethesda and chief of the international human genome project, wasn't
surprised the Novartis group concluded there might be more than 30,000
genes. He said his group's paper had emphasized the uncertainties
surrounding the preliminary estimate.
"It's clear that the methods we use to identify genes in long
stretches of DNA are imperfect," Collins said. "People will be
debating the precise number of genes for years to come, but we'll get
a narrower band in the next few years."
Craig Venter, Celera's president and chief scientific officer, also
agreed with the new study's conclusion. He said Celera's paper stated
about 11,000 of the 39,000 genes his group predicted were hypothetical
genes whose existence had not been confirmed.
"We still have a long way to go," said Venter, who predicted the final
tally of genes would fall between 25,000 and 35,000. "We're still
early in this field."
The gene tally is not the first challenge to the genome's analysis.
Scientists have questioned another much talked-about finding: that
hundreds of the genes were actually microbial genes left by bacteria
that infected human ancestors millions of years ago.
That claim was challenged in May, when researchers at the Institute of
Genomic Research in Rockville found the majority of those genes exist
in other animals, suggesting they are just basic genes left over from
evolution.
The 30,000-gene estimate came as a surprise because most scientists
had believed there were about 100,000 human genes. They wondered how
an organism as complex as a human being could be created with so few
genes.
Many scientists have challenged the 30,000 figure. One article in the
online journal Genome Biology estimated there were between 50,000 and
60,000 genes.
William A. Haseltine, chairman and chief executive of Human Genome
Sciences Inc. in Rockville, has said his company has identified 90,000
genes and estimated that the total may reach as high as 120,000 genes.
Most scientists dismiss that figure. Haseltine said the study
underscores the "very preliminary nature and sloppy interpretation of
the original data."
Although the two groups used complex mathematical formulas to make
their predictions, Haseltine said company scientists isolated the
genes themselves. "Ours is not speculation," he said. "Ours is based
on actual physical observation."
John B. Hogenesch, the Novartis study's coauthor, said the new study
demonstrates the value of having two genome maps, which allows for
comparison.
"This really is a very complex problem, and we really don't have the
answers yet," Hogenesch said. "Sometimes that's just as important as
having the answer."
