With each question answered, a new question askedBy Jonathan Freedhoff, M.D.
Try to count to 3 billion. It will take about 200 years -- if you don't lose count. That has basically been the challenge for the Human Genome Project (HGP) geneticists for the past 14 years. Their quest has been to decipher the roughly 3 billion bits of information that makes up human DNA. Amazingly, on June 23 of this year, they completed their task.
So how will the HGP discoveries affect you? The truth is, medicine as a whole has been deceivingly impersonal until now. Sure, we can measure your blood pressure, cholesterol, and blood sugar, but the cornerstones of medical treatments have been based on the masses -- with very little thought given to the individual you. Thanks to the HGP, however, there will soon be literally more of you involved, and it is going to change, well, everything.
Born in 1986 out of the ashes of the cold war and eventually funded by the Department of Energy (DOE), the HGP was originally designed to assess the effects of radiation on human cells. By 1988, the National Institutes of Health (NIH) was brought on board, and by 1990 it was obvious that a better understanding of our DNA would have much broader implications than simply the assessment of radiation damage. New objectives were put into place, and today the HGP is an international research program with an NIH/DOE-funded annual budget of more than $300 million and researchers spanning the globe. The effort involves several countries around the world, with the ultimate goal of constructing a highly detailed genetic and physical map of human DNA. That feat was expected to be complete no sooner than 2003. The mapping of a second chromosome this spring, however, accelerated the HGP's progress by exactly three years. It took only weeks to complete the entire mapping project.
Only time will tell what wonders our genetic code will reveal to us. But what is absolutely certain is that the HGP's medical, legal, and ethical implications are nothing less than staggering. In order to understand those implications, we must first understand the project itself.
Deoxyribonucleic acid, or DNA, is the foundation of life on earth, and a good place to start. DNA is found in virtually every cell in your body. It is your "hereditary blueprint" and, as such, provides detailed instructions to your body's molecular machinery. Each of these instructions is encoded in a region of DNA known as a gene. It is estimated that we have anywhere from 50,000 to 100,000 genes -- all of them housed by our two sets of 23 chromosomes. Each set of chromosomes contains half of the genetic makeup of one of your parents. Combine the two halves and you are left with the uniqueness that defines you and you alone, in your own personal version of the human genome. There are genes for everything -- from those that regulate our body's cholesterol to those that encode for hair color, and perhaps even those that cause some of us to cry during sad movies. It may be said that our genes and DNA serve as the scaffold upon which we hang all of our experiences.
Perhaps foremost among the HGP's many goals was to decode every stitch of our DNA and ultimately map all of our genes. Believe it or not, your DNA is roughly 99.8 percent identical to every other person's on this planet -- being virtually the same, small genetic differences, or mutations, are extremely hard to find. Before the HGP, locating a gene involved in a disease would be as difficult as finding your way to the Sanger Centre for Genome Research armed with only a hand-sized pocket globe and no specific address. With the completion of the HGP, we will now have the genetic street signs and major intersections that we need in order to locate specific genes in weeks -- as opposed to the current processes, which can take months or even years.
For diseases with genetic components, scientists will be able to identify and clone (copy) their genes and the responsible mutations. Once identified, laboratory tests will be developed to help identify people carrying mutations that put them at risk of developing specific diseases. We have already begun to identify some of these genes; tests are already available for genes involved in breast cancer, muscular dystrophy, Huntington's disease, colon cancer, hemophilia, and many others. Diagnosis and risk prediction, however, are only the first few steps.
Prevention and therapy
Once risk is identified, gene-specific strategies aimed at prevention will be developed in what undoubtedly will become a new field of medical therapy: pharmacogenomics. With pharmacogenomics, doctors will prescribe prevention and treatment therapies specifically tailored to you. Once we identify a gene involved in a disease, we can then begin to investigate what it does. After we determine how the gene behaves, we will have new understandings of the disease in question. These understandings ultimately will lead to new drug therapies and, in some cases, gene therapy. Instead of treating the results of a genetic disorder, we will treat the disorder itself. For example, in treating someone with very high cholesterol, instead of prescribing cholesterol-lowering medication, we will be able to prescribe a medication that targets the patient's specific genetic makeup.
Even further down the road may come the unravelling of non-disease and behavioral genetics, and with that will come the possibility of genetic enhancement. Once we understand how our genes are involved in intelligence, strength, and creativity, for example, it may be possible to buy medicines to make us smarter, stronger, and more creative. It may even be possible to make these modifications permanent by changing or adding genes to our children while they are still in the womb.
Ethical and legal implications
The excitement over what we can do with this information may overshadow the deeper question of ethics and what it means to be "human" in the spiritual sense. Therefore, the HGP's discoveries are very controversial. To help address some of the issues early on, 3 to 5 percent of the HGP annual research budget is mandated to exploring the ethical, legal, and social implications of genome research. Genomic law and policy making will likely become an entirely new industry. Below are just a few of the many tough questions we will be facing.
Perhaps the first issue that will reach public debate is that of information ownership in a pre-pharmacogenomic era. Standing today at the threshold of medical possibility, the first breakthroughs will be the identification of individuals with mutations in disease-related genes. Two very public and recent examples are Parkinson's disease and schizophrenia. What is not currently known (and probably will not be known for some time) is how much "testing positive" for one of these diseases increases a person's risk of developing the disease -- and what we can do about it. There have been no real medical breakthroughs in the treatment of either disease, so if we develop tests for these genes, what should be done with the results? Who should be privy to them?
The answers are not very straightforward. Consider, for example, an army recruit who "tests positive" for schizophrenia and a 40-year-old surgeon who "tests positive" for Parkinson's disease. Neither of these individuals currently suffers from those diseases, nor do their positive tests make their diagnoses inevitable. However, it may not be unreasonable for others to know. The army would probably want to know the test results because of the type of work the young man will be asked to do. And what about the surgeon? Her insurance company sure might like to know, given that she has just applied to quadruple her long-term disability coverage.
Soon after genetic diagnoses are explored, the era of true gene therapy -- therapy based on the structure and function of gene products -- will begin. Inevitably, the research and development costs of these new therapies will be astronomical at first. As consumers, patients will surely want the best possible therapy, but what if the therapy confers only slightly improved outcomes over current medications, yet rings up at ten times the cost? Will Medicare and Medicaid embrace these costs? We will also likely see the advent of therapies targeting previously untreatable diseases. At first these therapies may offer only the most modest of benefits -- which again begs the question: Who will pay for them?
These questions are not exclusive to Medicare. Currently, most private health insurance plans apply the expressio unius est exclusio alterius doctrine, which holds that when a plan contains a list of specific treatments and therapies, those not listed -- gene therapy among them -- are presumed to be excluded. Many current plans also invoke prospective utilization review as a means to address new therapy. What this means is that prior to initiating therapy, a physician would need to obtain the plan's agreement -- a lengthy and uncertain process.
Now we come to the most sensitive issue of all: enhancements. At first enhancements could be restricted to the increased use of "therapeutic abortions." After a battery of genetic tests, which may provide some indication of how strong, smart, and tall their child will be, some parents may elect to abort based on some preexisting "character flaw." This is a worst-case scenario, of course, but entirely plausible, since it is legal for parents to abort for any reason. Another possibility is the genetic alteration of an early-stage embryo to reduce those potential "character flaws" or a genetic predisposition for a disease.
This alteration would affect all fetal cells, including those that will eventually become its own sperm or eggs. In turn, these genetic enhancements would then be passed on to the grandchildren. Does one have to consider the rights of the child in these circumstances? Does a child have a right to its original genetic endowment without manipulation by its parents? If the answer is no, it may change our cultural, political, and even economic future -- invariably these enhancing procedures will be exorbitantly expensive and therefore reserved for people who can afford them.
Again, the worst-case scenario is this: The rich could go on to create genetically superior children who, armed with their enhancements and inheritances, would go on to further delineate a stricter class structure. And because their enhancements would be passed on to their own children, within a few generations an entirely new subclass of people would arise with unheard-of genetic power and privilege.
Some have called the HGP "the moon shot of biology." Like the space program, it has and will serve to generate a tremendous amount of new technology and potential. Individuality will be analyzed like never before. Doctors and geneticists will prescribe highly personalized strategies and medications for disease prevention. New classes of drugs with far fewer side effects will be designed to treat everything from cancer to depression. And while your doctor may soon be able to accurately and effectively diagnose, prevent, and treat a multitude of diseases, your own personal strengths and weaknesses may also be given genetic diagnoses.
There are many difficult questions left to answer, and even more to be asked. Perhaps the next 50 years will one day be looked at as the dawn of a new era in which medicine, ethics, and law served to forge an entirely new set of societal and social constructs. One thing is for certain: The stuff that dreams were made of has arrived.