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Completion of Human Genome Mapping Raises Hope for New Cures

2003 was a landmark year for genetic research, as scientists finished mapping all the human genes. In the process, they located genes that play a role in such diseases as colon cancer, schizophrenia, breast cancer and obesity. But it doesn't mean cures are around the corner for these and other ailments.

In the spring of 2003, scientists made a monumental announcement. After ten years of hard work, they had completed the Human Genome Project, the U.S.-led effort to catalogue some three billion DNA letters strung along two cellular chromosomes, one from each parent, that program how we are put together.

Alex MacKenzie is vice president of Genome Canada, whose researchers were the first to sequence the virus responsible for Severe Acute Respiratory Syndrome (SARS), a discovery that is hoped will lead to a treatment and vaccine.

Genome Canada's work is an outgrowth of the Human Genome Project, which still leaves Dr. MacKenzie awestruck. "With the sequencing of the genome, hundreds of thousands of protein structures were known in one fell swoop, [an] absolutely mind-blowing revelation," he said. "So, it really is one of the transformative shifts that will ever happen in biomedical research. Perhaps the most transformative shift."

So far, some 1,400 disease-causing genes have been identified. But with the current technology, Dr. MacKenzie says developing gene therapies is extremely complicated.

For hundreds of years, Dr. MacKenzie says, diseases have been treated in a hit or miss fashion. Mostly traditional therapies work, but all too often they don't.

Genes produce and regulate proteins and molecules that are involved both in normal functioning and, when they go awry, disease. By knowing specifically which proteins influence a particular disease, researchers hope they can develop precise therapies.

This year, investigators in New York and Australia began a clinical trial involving a therapy to treat patients with Parkinson's disease, a neuro-degenerative illness that causes severe tremors, muscle rigidity and poor coordination.

The first of its kind trial will test the safety of the therapy which may involve up to twelve people with Parkinson's. The genetically-modified drug is carried to the brain by harmless virus particles, and is designed to calm an overactive brain region by inserting corrected genes. Researchers stress the treatment is not a cure, but if it works, it would be much less invasive than an operation now performed to implant an electrical device that has the same calming effect.

Michael Kaplitt of Weill Medical College at Cornell University in New York performed the first operation in the gene therapy experiment.

Dr. Kaplitt notes it's easier to develop therapies for disorders that involve only one defective gene, such as Parkinson's, instead of diseases that are caused by many genes. "There are a lot of diseases where surgery is not normally done for those disorders," he said. "And Parkinson's disease happens to be an area where putting a needle in and injecting a virus, lets say, is not all that different than putting a needle in and then inserting an electrode in that place. So, there are a lot of things in Parkinson's that provide the framework for developing a gene therapeutic. And it is then safe and hopefully effective in Parkinson's, that then provides the platform for more complicated diseases of the brain." Experts agree that the first fruits of the human genome map will be in the area of diagnostic testing.

Tom White, chief scientific officer with the biotechnology company Celera Genomics, says Celera is using data derived from the Human Genome Project to develop tests to screen for diseases. "For example, in the case of heart attacks, a large number of people don't have high cholesterol or high blood pressure, but they still have a heart attack," he said. "And there's no current way of predicting those people or selecting certain kinds of therapies that might prevent a future heart attack."

But if you are a patient with a particular disorder, Genome Canada's Alex MacKenzie admits the benefits of the human genome sequencing are not apparent. "Basically in most cases, not yet all cases, the pay-off in the genome sequencing have not yet arrived. It will," he said. "I am absolutely confident that our knowledge based on the genome is going to have an enormous impact."

Dr. White and other scientists predict cures resulting from the Human Genome Project could start trickling in within the next five years.