FP Report -- November 1998 Results of human genome research will challenge, help family physicians
As you review the charts of two young asthmatic patients, you wonder why one of them has responded well to the albuterol bronchodilator you prescribed, while the other hasn't.
A 20-something white male patient tells you his lifestyle includes multiple sexual partners, both men and women, in a community rampant with HIV infection. He also abuses heroin. You're amazed he's HIV-free and don't know how long his good luck will last.
An adult female patient who's been suffering from fatigue and arthritis now has adult-onset diabetes. You recall that her late father, also your patient, had some of these problems, and you ponder the possibility of a genetic link.
A government project that's ahead of schedule and under budget will likely answer these and many other questions. It will substantially change the practice of medicine -- and the changes may begin within the next five years, according to Francis Collins, M.D., Ph.D., director of the National Human Genome Research Institute at the National Institutes of Health in Bethesda, Md.
This "next revolution in medicine" will fall on the shoulders of physicians who provide primary care, Collins said recently. The demands on family physicians will be significant as they gear up to provide information on genetic testing to their patients, help interpret test results for them and consider prescribing new genetic therapies that become available, he said.
The Human Genome Project is an international effort to map out the entire human genetic blueprint. Started in 1990, the project's goal is to construct detailed genetic and physical maps of the human genome, to determine the complete nucleotide sequence of human DNA, to localize the estimated 50,000-100,000 genes within the human genome and to perform similar analyses on the genomes of several other model organisms. The project also is charged with assessing the ethical, legal and social implications of its work.
The project has a yearly federal budget of $200 million, and it's currently 25 percent under budget, Collins said. The "finish date" of 2005 is being moved forward to 2003 because of rapid progress. More than half of all human genes have been mapped, with the information available on a web site.
Collins shared two principles explaining why genetics will play an increasingly important role in family practice:
Principle 1: Virtually all diseases except trauma have a genetic component. Even for conditions usually thought of as environmental, such as infectious diseases, genes dictate how the body will cope with the environmental challenge. For example, a recent study suggests that 1 percent of the Caucasian population lacks a specific cell-surface protein, rendering them completely resistant to HIV.
Principle 2: There are no perfect genetic specimens. People have an estimated five to 50 significant genetic flaws, some as subtle as one base pair gone awry in a chromosome, Collins said. While some mutations may be protective, many will place people at risk for something, especially as they age.
Some developments Collins shared:
- Population-based genetic screening for hemochromatosis is being intensely discussed and may occur within the next five years. The screening test is straightforward, and the condition is easily treatable if diagnosed early, Collins said. Left untreated, it can lead to fatigue, arthritis, diabetes, cirrhosis and heart failure.
- Genetic tests eventually will make it possible to tailor drug therapy. For example, albuterol's effectiveness varies according to the patient's genetic makeup.
- Cystic fibrosis researchers now understand what's wrong at the molecular level and have come up with new drug therapies; as a result, three new CF drug trials are under way. In addition, research using plasmids to insert the properly working genes into upper airway cells has met with mixed success -- the strategy improved function, but the altered cells were soon wiped out by the immune system. In 1997, an NIH consensus conference recommended that a CF carrier test be offered to all adults considering having children, on a population-wide basis.
The National Coalition for Health Professional Education in Genetics was established in 1996 in response to the rapid pace and impact of human genetics research. More than 100 health care professional organizations are coalition members, including the AAFP. Collins said the coalition has developed a web-based genetics information center (see web site information below) and is working on core competencies in genetics for medical school curricula and for continuing medical education.
Collins presented "The Human Genome Project and the Future of Medicine" Sept. 19 at the AAFP Scientific Assembly in San Francisco. During his lecture, he shared the web addresses of these medical genetics web sites: http://www.medsitenavigator.com/NCHPEG -- National Coalition for Health Professional Education in Genetics; http://www.nhgri.nih.gov -- National Institutes of Health National Human Genome Research Institute; http://www.cdc.gov/genetics -- Centers for Disease Control and Prevention; http://www.er.doe.gov -- Department of Energy's Human Genome Program; http://www.ncgr.org -- National Center for Genome Resources; http://www3.ncbi.nlm.nih.gov/omim/ -- Online Mendelian Inheritance in Man; and http://www.hhmi.org/genetictrail -- Howard Hughes Medical Institute.
By Paula Binder, Editor
FP Report is published by the AAFP News Department. Copyright © 1998 by American Academy of Family Physicians.
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