The Promises and Perils of Personalized Medicine
by Christina M. H. Powell
From experience, we know that one size does not fit all in medicine. A cancer treatment that leads to remission in one patient may have no effect in another patient. A drug may produce dangerous side effects in only a small percentage of the population. The effective dose for a medication may vary even among patients in the same age group with similar characteristics.
Throughout the history of medicine, predicting how a particular patient will respond to a treatment has been a frustrating challenge for doctors. Yet, the emerging science of pharmacogenetics — the study of how and why specific medications work only in certain populations — promises to clarify the mystery, allowing doctors to tailor treatments to individual patients.
Pastors who walk alongside parishioners experiencing serious illnesses support them emotionally and spiritually. When a treatment fails to work for a patient, doctors and patients lose valuable time. This often dashes any hope for recovery. A patient may suffer emotionally and spiritually as well as physically. Personalized medicine can reduce the frequency of these medical failures. Most pastors would consider such a medical advance to be a great blessing.
Yet, for personalized medicine to work, doctors need to test the patient’s genetic makeup. Since a person shares genetic information with biological family members, when a patient undergoes a genetic test, the results may have implications for the rest of the family. The genetic test yields personal information that can produce the potential for good or for harm. As personalized medicine becomes more commonplace, pastors may find themselves ministering to individuals and families trying to make sense of the promises and perils of this new tool.
Tailoring Treatments to the Patient
In the last decade, personalized medicine has seen its greatest successes in treating cancer. Drugs can target a genetic mutation that is limited to cancer cells, not the patient’s normal cells. Therefore, these drugs will have fewer side effects than traditional chemotherapy. Drugs such as Herceptin for breast cancer, Gleevac for chronic myeloid leukemia, and Iressa for non-small-cell lung cancer are examples of cancer drugs that work well for patients with certain genetic mutations in their tumor cells.
Pharmacogenetics extends beyond cancer treatments. Researchers have found that genetic testing using microarray technology (a two-dimensional array of DNA on a small glass chip) can predict adverse reactions with antidepressants. How quickly certain liver enzymes, called cytochrome P450 enzymes, process a drug determine the drug’s effectiveness and safety. If liver enzymes metabolize a drug too quickly, the drug will be ineffective. However, if the liver enzymes work so slowly that the drug accumulates, an otherwise safe medication might poison a person. In rare cases, a patient may be unable to process certain drugs at all, resulting in both ineffective treatment and unwanted side effects. Genetic information can provide doctors with dosage guidelines.
As another example, researchers recently found that about 30 percent of people carry a genetic variation that prevents them from properly metabolizing the antiplatelet drug clopidogrel, or Plavix, commonly prescribed to prevent heart attacks. These patients need either a higher dose of the drug or a different anticoagulant medication.
In the future, pharmacogenetics will enable researchers to design safer and better medications. In a decade, doctors may be able to analyze a patient’s genetic blueprint during a routine office visit, with genetic testing becoming as common a diagnostic tool as a urinalysis or a blood count.
Considering Implications for the Family
Since we share genetic information with biological family members, a genetic test has implications for the patient’s family that other diagnostic tools, such as a blood count, do not. For example, if a granddaughter chose to undergo genetic testing after seeing her grandfather suffer from Huntington’s disease, her test results would also reveal her mother’s carrier status. Tension can arise in families when family members disagree over whether they want to discover genetic bad news ahead of time. As genetic testing becomes more prevalent, pastors may need to counsel families in conflict over differing views on this technology.
When genetic testing involves children, parents must make decisions that will impact their children’s future. Furthermore, genetic testing may reveal which side of the family is the source of the disease-causing mutation. A good genetic counselor will remind parents that each person carries an estimated 6 to 25 genes that could trigger a disease in his or her offspring under certain circumstances. A pastor can help parents receiving difficult medical news avoid the unproductive responses of blame and guilt.
Patients are accustomed to keeping certain medical details private. However, when knowledge of the results from genetic testing can affect the medical care of other family members, does a physician have a duty to warn those family members? Most of the time a doctor simply encourages patients to share test results with their family members. However, if the patient dies before having opportunity to share those results or refuses to disclose the information, the doctor may be sued for failing to warn the family.
Finally, for many diseases, a genetic mutation simply indicates an increased health risk, but not a certain diagnosis. A person’s environment and lifestyle influence whether or not a genetic risk ever translates into a disease. Our genes do not necessarily determine our destiny, but they do speak to future probabilities. In many cases, taking responsibility for our health and making wise choices can prevent a genetic weakness from manifesting. From a spiritual perspective, pastors can discourage fatalistic thinking, reminding parishioners that that “nothing is impossible with God” (Luke 1:37).
Preventing Discrimination in Society
The implications of genetic testing extend beyond the family unit to society as a whole. To prevent discrimination based on genetic information, we need to ensure patient privacy. The Genetic Information Nondiscrimination Act (GINA) of 2008 prohibits genetic discrimination by health insurers and employers and grants the same privacy protections to genetic information that the Health Insurance Portability and Accountability Act (HIPAA) provides for medical records. GINA prevents health plan administrators from charging an individual a higher premium based on a genetic predisposition to develop a disease. However, once a genetic disease manifests, the protections of GINA no longer apply. GINA also does not affect life, disability, or long-term care insurance.
Beyond legal protections against discrimination in employment opportunities and insurance coverage, we need to consider any social stigmas that might arise from genetic testing. As the price to sequence a person’s genome (complete genetic blueprint) falls below $1,000, we could enter an era where doctors analyze a child’s genetic information at birth and make it available to plan future health care. Theoretically, individuals could use such information to determine the genetic compatibility of a potential marriage partner. How would a child’s knowledge of genetic weaknesses, even ones that may never manifest, affect the child’s view of himself? Would parents treat a child differently based on the knowledge of a child’s genetic strengths or potential to develop a life-shortening disease in adulthood?
Pastors might consider how knowledge of our genetic information could impact our spiritual life. From a broader viewpoint, discoveries about genetic variation remind us of our uniqueness. As King David declared nearly 3,000 years before the discovery of the DNA double helix, “I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well” (Psalm 139:14).
The challenge for individuals learning of their genetic strengths and weaknesses will be to affirm David’s response to God’s creation. Genetic predispositions, whether positive or negative, simply remind us of our uniqueness. Our genes show us the possibilities for our life, but they need not limit our potential. The Bible is filled with accounts of individuals who have achieved great feats in spite of physical limitations and social constraints.
Personalized medicine has the potential to ease human suffering and save lives. We should embrace the promises of this tool, while carefully considering how to protect patient privacy and prevent discrimination based on the most personal of all information. Ideally, study of genetic information should remind us that we all carry hidden weaknesses and untapped strengths. We each have been given different gifts to use for the benefit of others and for the glory of our Creator.