Human Genome Project faqs - Science Article

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By:Aaron Hall

Q. What is the value of the Human Genome Project?

A. My basic view is that the project will reap fantastic benefits for humankind, some that we can anticipate and others that will surprise us. Greater knowledge about the human genome will help us better understand the many diseases and heritable conditions that affect humans. Disease genes get all the attention, but much more profound is the need to understand normal biological functions. From this understanding will come insights into how to prevent diseases rather than rely on treatment after they start. The most cost-effective disease prevention ever invented is the vaccine. For the cost of smallpox vaccine or a tetanus shot, a life of incalculable value can be safeguarded at no further expense. Disease prevention— the gold standard for medicine—also represents the promise of genetics.

Another benefit will come from understanding genetic similarities between mammals and humans. There isn’t that much difference between human biology and cattle or pork biology (or mouse biology for that matter). What we learn about human genetics will help us to raise healthier, more productive, disease-resistant farm animals that might, through wise and careful genetic engineering, produce drugs of value to us. (Additional benefits and applications to various areas of research are given.)

Q: What concerns have been expressed about the Human Genome Project?

Genetic information can be used to make predictions about a person’s medical future, and possible invasions of privacy by employers or insurers can be worrisome. A very serious possibility is that misunderstandings about the limits of genetic information may lead to discrimination, and people may not understand that having a predisposing gene mutation is not the same as being condemned to get the disease. Discrimination can happen because it often is less expensive to adopt a blanket policy excluding people with predisposing genes.

Educating judges and others in the court system about the nature and implications of genetics, including its limitations, is very important. Most judges are not and never have been scientists, so they are inhibited and uncertain when scientific matter is entered as evidence in a trial.

One of the most difficult challenges for geneticists will be to study multigenic or multifactorial conditions (not all are even diseases) and those in which genes and environmental factors interact. Diabetes mellitus is a good example of a complex disease. We know that quite a few genes (at least a dozen) are influential in determining which individuals develop diabetes. We also know that in genetically identical twins, when one twin has diabetes, the other twin has only a 1 in 3 chance of developing the condition. So there is a 2 in 3 chance that the other twin will never get diabetes, even though the twins have identical genes. So, in this case, genetics can account for about one-third of the causation, and external or internal environmental factors account for two-thirds. Environmental factors involved in susceptibility remain to be elucidated.

Such complex diseases are much more common than single-gene conditions including cystic fibrosis (CF), sickle-cell disease, and Huntington's Disease. But even understanding a “simple,” single-gene disorder presents many challenges. For example, more than 600 alternative forms (alleles) of the CF gene have been identified, but their clinical effects are not yet known. Some alleles may give rise to the full-blown, fatal disease, whereas others apparently have little or no effect on the individual. Commercial gene tests available now present problems for doctors and patients in understanding the implications of a positive test, particularly when used prenatally. More research will be needed to determine the effects of each variant allele.

More than 250 alleles are associated with two genes called BRCA1 and BRCA2, which can cause a rare, inherited form of breast cancer. Is it appropriate to discriminate against every woman who bears a mutation in these genes? What use should be made of information that is not certain? Society is beginning to address these questions and many other implications related to the increased availability of genetic information.

Hardest of all, possibly, are questions surrounding the role that genes may play in human behavior. Which genes are they, how much do they affect behavior, and with what consequences? How would society use information about genes that affect behavior? If certain behaviors that may be influenced by genes are socially dangerous, what should we do about people who have these predisposing genes? Are those persons responsible for their behavior if brought before a judge and accused of criminal acts? If environmental factors such as drugs and alcohol are involved, where does responsibility reside?

These and other questions need answers that will come from more research and public discussions. The Ethical, Legal, and Social Implications component of the DOE Human Genome Program has been striving to find such answers since the beginning of the Human Genome Project.

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