By Luanne McNabb. Luanne McNabb is the Genetic Counsellor/Coordinator at Peterborough County-City Health Unit
"Uncorking the gene genie" was the headline of a recent article in The Globe and Mail (00/02/23). It is just one of countless articles in both mainstream and professional print and electronic media pointing to the profound discoveries and implications of the exploding field of genetics.
Genetic links are being made for an increasing number of disorders, so more physicians and consumers are asking for information for themselves and for their families. Genetic consultation and testing used to be considered as pertaining mostly to reproduction concerns, but is increasingly recognized as pertaining to disorders throughout the life span. Referrals are no longer limited to rare disorders, but regularly include diseases as "common" as cancer and heart disease.
As a genetic counsellor working in one of eight Ministry of Health-funded Outreach Genetic Centres in Ontario, the rapid changes in the field of genetics are regularly evident to me. The Peterborough program services a 5-county catchment and the number of consultations has tripled over the last 10 years. Prenatal issues account for less than 40% of our referrals, as the number for "adult" diseases rapidly increases. Individuals and families are referred to genetic counsellors for family history analysis, education, counselling about prognosis and testing options, and support services. Arrangements are made for diagnosis, testing and consultation with a Medical Geneticist (from nearby major Genetics centres) at one of our Outreach clinics. Most outreach genetics programs operate out of Health Units, and in addition to clinical services offer physician and community genetics education and awareness programs.
This OHPE issue is most obviously not a comprehensive course in molecular genetics, scientific research or bioethics, nor is it a credible critique on medical practice or health care economics and politics. Rather, it should serve as a catalyst, or better yet, an appetizer enticing you on to learn more about how this "genie" affects you, your family and your professional practice.
B. The Human Genome Project: Understanding the Terms
"Imagine a world where baldness is a thing of the past, cancer is not a terminal illness, and hemophilia is not a life-threatening disorder. It sounds like a scenario from Star Trek, where a push of a button eliminates human imperfections and ailments. Welcome to twenty-first century science and medicine, all courtesy of the ambitious Human Genome Project and twentieth-century molecular biology tools. This project could revolutionize medicine, making current practices look almost medieval by comparison. With an enormous storehouse of new information, it may unlock the secrets of cancers and may cure hereditary disorders." (Willingham, E. Human Genome Project: An update, HMS Beagle, Issue 74, March 17, 2000)
Human Genome: The complete genetic material found in the human cell. This material is packaged in 46 chromosomes, (or 23 pairs; we get one of each of the pairs from each or our parents!) which contain all of the estimated 100,000-140,000 genes of a human being.
Chromosome: A package of genetic information, made up of about 6 feet of a material called DNA. 23 pairs of chromosomes in each cell; 22 of the pairs are common to males and females, the last pair determines the sex of the individual - XX female, XY male. Sperm and egg cells usually have only 23 chromosomes, one of each pair, and conception then provides the 46 chromosome count.
Genes: Segments of DNA in a chromosome (like beads on a string) that has the code or recipe for making a specific protein, which, in turn, is the 'coding' for various traits: physical and psychological traits, development, ageing and disease processes. (The mechanisms for how we inherit and pass along traits like our aunt's crooked nose or our father's flat feet, or our family's tendency to get cancer.) Mutations, changes or "spelling mistakes" in these codes can result in variations of traits and processes; some of which we consider differences and some we consider diseases.
Human Genome Project: The Human Genome Project Organization (HUGO) is a U.S. government-initiated research and technology development effort. Started in 1990, it is an unprecedented 18-country international collaboration of medical researchers and scientists working to map and sequence all of the genes found in human cells. Work is ahead of schedule so its initial 15-year project goal has been altered and they expect to be done by 2003.
With all of our chromosomes mapped and genes identified, the results will be exciting and promising but also mind-boggling. We will have medical, ethical, psychological and political issues to deal with as they accompany the unprecedented number of choices in testing and treatment.
Human Genome Project Information - http://www.ornl.gov/hgmis/resource/medicine.html
Genetic Medicine of the Future: The Human Genome Project and Beyond (Dr. Francis Collins, Lecture audio and slides) http://www.nhgri.nih.gov/DIR/VIP/SI/Collins/
National Human Genome Research Institute http://www.nhgri.nih.gov
Introducing the Human Genome http://www.ornl.gov/hgmis/publicat/tko/03_introducing.html
~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *
C. Health Care Practice and the Public's Health
What do we want to know? Why do we want to know? And, when do we want to know it?
Instead of genetic testing being limited to those dealing with rare or less usual disorders, tests will be increasingly available for disorders as common as cancer and heart disease. A shift from a population-subset to public health proportions ensues, as the number of people seeking genetics consultation, family history analysis and testing options changes from hundreds to thousands.
When a gene is located and identified, the next steps towards diagnosis, prognosis and therapy are in sight. These choices offer much hope and promise; some immediate, some in the more distant future.
Some genetic tests have obvious benefits. Prenatal testing, for couples at higher risk of having a child with a genetic abnormality, can provide reassurance and anxiety relief for the duration of a pregnancy. A sick baby may be accurately diagnosed with a "simple" DNA blood test, and then quickly offered correct therapy or treatment. Regular medical screening can be implemented for those identified as carrying genes for some familial forms of colon cancer, and have any pre-cancerous polyps removed long before a life-threatening stage. Verifying that a particular disease in an ageing family member is not a familial, hereditary one can be useful and reassuring to younger members of the family.
But what about test results that don't provide reassurance, where no correction or cure is possible? Or what about DNA test results that are not definitive? For example, the BRCA1 gene, if present, means you have a 65-80% chance of developing hereditary breast cancer by the time you're 80 years old, not that you're certain to develop cancer. And what about the genetic tests that are and will be available to identify which diseases we will get in the future- the glimpse into the crystal ball- that at this point may have no known cure or treatment? Arguments for such predictive tests (psychological preparation, career, family and life experience planning etc.) and against (psychological trauma, eugenics, societal attitudes toward disability etc.) are abundant and complex. For or against, the array of choices, each with their own complex issues, are quickly presenting themselves. How do consumers, whether health care professionals or members of the general public, make the right choice for themselves?
Health Care Practices
There has been and will continue to be dramatic increases in the availability of genetic testing for a wide variety of conditions and disorders. It is essential to have informed consent before genetic testing, as there are significant social and emotional, legal and life insurance ramifications. Pre-test counselling is a must. Post-test counselling for genetic disorders, involving results interpretation, reviewing clinical options and communication of results to family, is also necessary and brings a unique cocktail of social and psychological issues.
Typically, if a question of genetic or hereditary disease arises, the community physician refers the individual or family to the nearest Genetics Centre for appropriate counselling and where possible, the offer of testing. While this will continue to work for the rare and seldom-seen disorders or syndromes, the onslaught of genetic links made for more common disorders will increasingly be dealt with in the family doctor's practice. With the advent of thousands of tests being available, the learning curve is steep, and even the decision of who should be referred to genetics is made difficult.
An example of the ensuing changes in genetic testing delivery practices is hemochromatosis. The genes responsible have recently been identified. Hemochomatosis causes iron overload in various organs and tissues and can lead to diseases such as diabetes, heart failure, and liver cancer. It is one of the most common inherited diseases, and easily treated if diagnosed early (or even prevented in siblings and children of those affected). This disease stands as a model of the great potential of gene-based diagnostics. It is estimated that 1 in 10 caucasians carry a gene for this disease, and 1 in 200 people are affected! Until recently, a genetic test of this kind would only be handled by Genetics Centres, but the numbers involved, and the clear gene identification/clinical benefit and management issues are moving this into the community physician's office. Routine population screening is being advised and population genetic screening is being researched. (Davidson, R. (1999) Advances in genetic testing. Medical rounds, Peterborough)
Recognizing whether or not genetic counselling for a particular disorder or condition may be useful necessitates family physicians increasingly being involved, but necessitates other health care professionals being involved also. These other health care professionals, who provide a variety of services to families, often have the opportunity to see, listen, question and refer about potential genetics concerns. They often have more opportunity to explore and discuss some of the emotional and psychological issues that surround coping with genetic disorders, and sorting through the value clarification and decision-making involved in choosing to have or dealing with genetic testing results.
~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ * ~ *
"It's difficult to imagine what will change as a result of the Human Genome Project. We could see the end of many major diseases. We could find out early in our lives what our health prognoses are decades down the road. While we enjoy the medical revolution that these new discoveries bring us, we will have to grapple with the consequences - potential loss of privacy, difficult reproductive decisions, and tough choices about our own genetic futures. It's a brave new world of science and medicine that in a few years - when the Human Genome Project is completed - will bring us face-to-face with our future." (Willingham, E. Human Genome Project: An update, HMS Beagle, Issue 74, March 17, 2000)
A most crucial step in dealing with the impact of the Human Genome Project is exploring and referring others to credible resources for more information on genetics issues and services. Have fun making your own discoveries in the resources and web-sites listed in this message and in OHPE #156.2 Resources on Genetics.
Peterborough County-City Health Unit
129-380 Armour Rd.
tel: (705) 748-2021
fax: (705) 748-3865