The code of life
A CNN Future Summit technology profile
By CNN's Michael Bay and Matt Ford
Understanding the human genome may enable scientists to manipulate the basic building blacks of life
We're switching from being able to read the genetic code for the first time in history to being able to write it.
-- Craig Venter
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ATLANTA (CNN) -- Genes are the basic building blocks of life, and in studying them genetic science is giving us the ability to adapt and alter ourselves fundamentally, providing unprecedented opportunities to improve on nature.
Terminal diseases and chronic disability could be prevented, and even death could be postponed as we learn more about how we are built, and how to fix our inherent physiological weaknesses.
At its heart genetics is all about studying inheritance and how an organism's parents influence its characteristics. But as the science has developed it has become possible to take a gene from one species and put it into an entirely different species in order to manipulate its characteristics and make it more useful to humans.
In the near future the same technology that is currently applied to plants and animals could be applied to humans allowing us to make a whole range of adaptations to both our own bodies and those of our children.
Think about the children
Generation after generation, children have inherited from their parents. Parents give their children culture, values, ideas, philosophies, knowledge, religion, and sometimes even wealth and property.
But most fundamentally, parents pass along their genetic code: The set of instructions that goes to work just after egg and sperm fuse to create an embryo, a baby, a child, and finally an adult.
Life's construction set, DNA, is made up of four key molecules (adenine, thymine, cytosine, and guanine), strung together in pairs to form an extremely long chain, known as a chromosome.
Human beings normally have 46 chromosomes in 23 matching pairs. We inherit half of our chromosomes from our mothers, half from our fathers. Along each chromosome chain, the adenine, thymine, cytosine, and guanine molecules are paired off, and unevenly arranged into discrete segments called genes.
And genes, to a large extent, determine who you are. For example, three genes are known to determine the color of your eyes.
Decoding the code
In 1999, science celebrated one of its greatest achievements, when Craig Venter of Celera Genomics and Francis Collins, director of the National Human Genome Research Institute announced that they had independently completed rough drafts of the sequence of the human genome.
Genome is the word used to describe all of the genes in our DNA. Sequencing the human genome meant sifting through the three billion pairs of molecule pairs that make up our chromosomes to find the genes themselves.
And it meant unlocking the road map of our lives: How our bodies form, grow, age, and die. "It's hard to overstate the importance of reading our own instruction book," said Collins at the time.
Genetic sequencing on other life forms, including viruses, is an important tool for medicine. In 2002 when people suddenly began to fall ill with an unknown illness, it was genetics - DNA analysis - that rapidly identified the cause as Severe Acute Respiratory Syndrome (SARS). Genetics plays an increasing role in efforts to prevent and counter disease.
The next steps
"What we did with sequencing the human genome," Venter says, "is leading to a better understanding of what causes disease."
The ten year race to sequence the genome presented researchers with grand new challenges.
Knowing where the genes that affect us are in our DNA is just the start.
Learning how all of the individual genes interact to influence a trait, such as eye color, is important. Genes provide the instructions for creating proteins. And while there are an estimated 30,000 genes in our DNA, there are 100,000 proteins in our cells. Understanding how those proteins interact is already resulting in medical treatments.
Formulated to specifically target the cause of a disease, the new wave of drugs are more effective than their predecessors. For example, Gleevec, a drug designed to fight one form of leukemia, is proving to be effective. The drug turns off the effect of a protein that causes cancer.
"The drugs that we give in 2020 will for the most part be those that were based on the understanding of the genome," says Collins. "The [drugs] that we use today will be relegated to the dust bin."
Testing for genetically related conditions was being done on newborns in the 1960s. But in the following decades, scientists learned to examine DNA itself and search chromosomes for indications of abnormalities. In the 1980s, researchers were able to isolate genes responsible for diseases like Cystic Fibrosis and Muscular Dystrophy. In 1991, a gene that can predispose women to breast and ovarian cancer was discovered.
Genetic testing now and in the future will help doctors provide patients with focused, individualized courses of treatment that goes beyond medicine. Knowing someone has a genetic predisposition for a condition or disease gives doctors the chance to prescribe a course of action that could prevent the problem from ever developing.
"If you can identify individuals who are susceptible to developing something," says Lyn Griffiths, head of the Genomics Research Center at Griffith University on Australia's Gold Coast, "you may be able to introduce things like lifestyle counseling, dietary changes, lifestyle changes that may well stop the actual development."
Griffiths, a member of the CNN Future Summit Nominating Committee, is focused on understanding the underlying genetic cause of migraine headaches. "Three times more women suffer from migraine than men do and it's strongly genetic."
Genetic testing isn't perfect. For example, a recent report from a University of Washington cancer researcher indicates that one test to identify genetic risk for breast cancer may be inaccurate in some cases.
The potential for mistakes, in clinical settings or with increasingly popular home testing kits, leads many to worry about decisions people may make based on faulty results.
Science has been tinkering with the genetic code of organisms for decades. Replacing one or more genes in the genetic code of an organism alters that life form's function.
Looking ahead, the possibilities are mind-boggling.
"In the next couple of years," says Venter, "we'll begin to really understand the principals of biology and be able to harness that tremendous knowledge and see if we can do something about reversing dangerous trends on this planet."
Venter has ambitious plans. "We're switching from being able to read the genetic code for the first time in history to being able to write it." Venter is engineering artificial life forms to create new sources of energy and to fight environmental pollution. "I think that's going to happen over this next decade," he says.
Tweaking the genetic code of other life forms to serve our purposes is one thing. Changing our own genetic code is a bit more challenging, and fraught with controversy. But genetic therapy, the ability to alter the genetic code of a living being, has the potential to save lives.
Ashanthi DeSilva was born with a defective gene that prevented her immune system from functioning properly. In 1990, when she was four years old, doctors used her own white blood cells to introduce a corrected version of the gene into her system. It was the first approved use of genetic therapy in the United States. It appeared to work, although to be safe Ashanthi continues to take medications for her condition.
Unfortunately, the potential of genetic therapy has not been realized. In 1999, 18-year-old Jesse Gelsinger died undergoing experimental gene therapy in Pennsylvania. Jesse's death resulted in a major investigation and reevaluation of gene therapy.
Still, the possibilities of gene therapy remain. And patients who suffer from many genetically related diseases and their families hold out hope that otherwise incurable conditions may be candidates for gene therapy in the future.
There are a number of exciting possibilities ahead.
Understanding with precision the function of our genes and interaction of our proteins will allow for the creation of extremely efficient drugs to treat a wide variety of diseases.
Personalized medicine, including individualized lifestyle and diet plans, will help us live longer, healthier lives.
Artificial or engineered life forms, their genetic code written in laboratories, could potentially solve problems from energy to environment.
Cosmetic genetic engineering may alter what it is to be human. These possibilities include everything from altering your metabolism, changing the color of your eyes, restoring hair to a bald head, to changing your appearance and increasing your mental and physical abilities.
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