01 April 2010

Human genome turns 10

A decade after the sequencing of the human genome, scientists muse on how far they've come and how far there is still to go.


A decade after the sequencing of the human genome, scientists muse on how far they've come and how far there is still to go.

Without doubt, the publication of the genome draft in 2001 permanently altered the scientific and medical landscape, although changes to individual lives are slower to come, according to scientists writing in the April 1 issue of Nature.

"It's still a fairly early stage in the transformation," said Dr Francis Collins, director of the US National Institutes of Health. "Most people's medical care has probably not been directly affected so far by things that have come along since then. Most of the revolution lies ahead in the next 10 to 20 years."

Collins was director of the National Human Genome Research Institute from 1993 until 2008.

Most predictions came true

For his piece in Nature, Collins dug up old PowerPoint slides to find predictions he had made in 2000 for 2010. Most have come true.

For instance, he was correct in anticipating that predictive genetic tests would be available for various medical conditions, along with interventions to reduce the associated risk.

Tests for the BRCA1 and BRCA2 genes, which elevate a woman's risk for breast and ovarian cancer, are now commonplace, as are assays to identify people who are at higher risk for colon cancer because they have specific gene mutations.

And once found, there are ways to minimise the genetic dangers. In the case of the BRCA genes, this may mean removing the ovaries or breasts in return for a risk reduction of almost 100%. For those genetically at higher risk for colon cancer, annual colonoscopies starting at age 30 instead of 50 saves lives.

Drugs customised

Mapping the genetics of tumors has resulted in the development of drugs that more accurately and effectively target weaknesses in cancers. Place the breast cancer drug Herceptin, which targets the HER2/neu receptor, in this category.

Using genetic testing, doctors can now also predict the response of particular tumours to particular drugs, or rule out toxic therapies that aren't needed.

"One breast cancer test that is a direct consequence of our understanding of our genome allows women with negative lymph nodes at the time of surgery to find out whether they need to go through chemo or not, which can prevent a great deal of unpleasantness and is saving our health-care system about $100 million this year," Collins noted.

What hasn't happened?

"We aren't able to predict who's at risk for more common diseases, like coronary artery disease or hypertension or stroke or asthma," said Dr Robert Marion, chief of genetics and development medicine and director of the Centre for Congenital Disorders at Children's Hospital at Montefiore Medical Centre in New York City and author of Genetic Rounds: A Doctor's Encounters in the Field that Revolutionized Medicine.

And while "the $1,000 genome is virtually a reality," said Dr James P. Evans, editor-in-chief of Genetics in Medicine and a spokesman for the American College of Medical Genetics, "interpreting that information will be a monumental task; one that makes the Human Genome Project look like small potatoes."

"Whole genome sequencing will be the first medical test in history which is guaranteed to be abnormal in every single person who undergoes it," Evans added. "We are all mutants. The challenge will be how to interpret and use that information for better health, and that path is a much more complicated one than simply deriving the basic genomic sequence of a representative human."

What does Collins predict will happen now?

The cost of sequencing the human genome could drop even lower than $1,000, he said. "There will be increasing reasons for each of us to have our complete genomes determined and placed in medical files," Collins noted.

"Five years after that, there will be compelling enough evidence that this is good medicine for both prevention and treatment that third parties will cover the cost," Collins said. "Health-care providers will have immediate access to [this information] about you, about what decisions to recommend. It's not one-size-fits-all, but really just about you."

"When I was in training, genetics was a small insignificant subspecialty of paediatrics," Marion noted. "And now paediatrics is a small insignificant subspecialty of genetics." - (Amanda Gardner/HealthDay News, April 2010)


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