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Mapping the Human Genome: History in the Making

Mapping the Human Genome: History in the Making

Do you remember where you were when it was announced that the human genome had been successfully mapped? It’s a bit of a facetious question, but the event was so momentous—somewhat akin to Neil Armstrong’s walk on the moon–that we should have taken note.

In only 15 years, genome sequencing has changed the way medicine is practiced. The sequencing of the human genome has given the world the instruction manual for making and maintaining the human body.

This history of genome sequencing is a long and winding road. But, it traces its beginning to the blueprint of life itself – DNA.

A (Brief) History of DNA

In the 1950s, James Watson and Francis Crick discovered the structure of DNA. Because the function of DNA depends in large part on its structure, identifying it as a double helix allowed researchers to unravel the fundamental role of DNA in biology, heredity and how genetic instructions are passed from one generation to the next. Crick and Watson’s research is the foundation on which today’s genomics is built.

In an interview with NPR marking the 50th anniversary of Crick and Watson’s discovery, Francis S. Collins, director of the National Institutes of Health (NIH) and former leader of the Human Genome Project (HGP), says the structure of DNA is essential to our knowledge of genetic code:

“[DNA’s structure] is so intertwined in every bit of what we do experimentally, in terms of perceiving our own position in the scheme of life on this planet. It has become one of those givens that is so central to your thinking that you stop thinking about it, but if somebody took it away from you, your whole intellectual foundation would collapse, and it would be unimaginable what we would be doing now if we didn’t know about the double helix.”

After Watson and Crick: A (Brief) History of the Human Genome Project

HGP began in 1990 when the NIH and the Department of Energy collaborated with 20 institutions in six countries including France, Germany, Japan, China, the UK and the US to sequence the human genome. Why? A genome is a complete set of DNA, and has been referred to as the “instruction book for human biology.” It was felt that doing so would open the window to the human mind and body.

However, these institutions had some competition. Craig Venter, a biotechnologist, biochemist, geneticist, and businessman thought his company, Celera Genomics, could finish the sequencing better and faster using different systems.

The race was on to map the human genome. And it was a photo finish. Officially, Celera beat the HGP by several months.

In April 2003, scientists announced that they had sequenced the human genome, compiling a list of the three billion letters of genetic code that make up what researchers thought was humanity’s common DNA.

What they accomplished was game changing. In 2013, the tenth anniversary of the accomplishment, The New York Times talked to Eric D. Green, the director of the National Human Genome Research Institute at the National Institutes of Health, who spoke about what the mapping meant:

“The best analogy is to GPS in a car. It is nice to have a highway map, but you really want to know where is the shopping center, where is the gas station, the next park, a restaurant. We want to know where are the genes, the parts of the genome that code for proteins. Where are the places on the genome that people tend to vary? Where are the genes that code for diseases?
“People differ in only one out of 1,000 bases, so that reference genome is 99.9 percent identical to any person’s genome. We used that tool to build sort of a highway map. We could go through it and add information about what was important.”

The Future with Genome Sequencing

Today, sequencing a human genome can cost less than $5,000 and take only a day or two. Doctors can now use DNA analysis to diagnose challenging cases.

MIT’s Technology Review, in its “A Decade of Advances Since the Human Genome Project” round up, said genomic sequencing has made advances in:

  • Cancer – Genomics is making its biggest strides in cancer medicine, with doctors now able to sequence a patient’s tumor to identify the best treatments. Specific drug targets may be found in as many as 70 percent of tumors.
  • Prenatal Care – The declining cost of DNA sequencing is changing prenatal care. A pregnant woman now has the option to eschew amniocenteses or other invasive methods for checking for chromosome aberrations in her fetus. Instead, she can get a simple blood draw.
  • Medication – Prescriptions are also changing because of genomics. More than 100 different FDA-approved drugs are now packaged with genomic information that tells doctors to test their patients for genetic variants linked to efficacy, dosages or risky side-effects.

Genome Sequencing & GeneSight

Mapping the human genome has also led to the birth of pharmacogenomics, the study of genetics and drug response. GeneSight, a pharmacogenomic test that examines how a patient’s DNA responds to specific medications particularly those used to treat behavioral disorders, is an example of genome sequencing in practice.

On Aug 19, 2008, James Watson and Craig Venter–the genetic pioneers instrumental to the successful genome sequencing—had their own genomes decoded, and thereby exhibited—albeit unwittingly–an early application of pharmacogenomics. The sequencing revealed that out of six genes known to play key roles in metabolizing medicine – the same six genes included in the GeneSight psychotropic test – Watson and Venter had three that were identical and three showing variations that could result in different reactions to several common drugs. Professor Watson had a mutation in a drug-metabolizing gene which meant that antipsychotic drugs and certain antidepressants would not work as well for him as with Dr. Venter.

Unlike Watson and Venter, patients do not need to have their entire genome sequenced to benefit from that kind of information. They need only a simple cheek swab for the GeneSight Psychotropic test to analyze how their bodies will metabolize 97 percent of prescriptions written to treat depression, anxiety, bipolar disorder and schizophrenia.

In doing so, their physicians can unlock the window into which medications will most likely help their patients with fewer side effects.

The future, post-genome sequencing, is full of incredible opportunities. Medical advances have been accelerated to what today seems light speed.  You may not remember where you were when the HGP was completed, but where we are going is as boundless as the universe.

This blog is for informational purposes only and does not constitute medical advice. Do not make any changes to your current medications or dosing without consulting your healthcare provider.

The GeneSight test must be ordered by and used only in consultation with a healthcare provider who can prescribe medications. As with all genetic tests, the GeneSight test results have limitations and do not constitute medical advice. The test results are designed to be just one part of a larger, complete patient assessment, which would include proper diagnosis and consideration of your medical history, other medications you may be taking, your family history, and other factors.

If you are a healthcare provider and interested in learning more about the GeneSight test, please call us at 855.891.9415. If you are a patient, please talk with your doctor to see if the GeneSight test may be helpful.

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