Be Cautious of Genetic Testing

Be Cautious of Genetic Testing

In mid-2016, a cheek swab of a middle-aged woman was sent to a laboratory to be analyzed for a number of genetic markers, particularly those relating to cancers. These included BRCA1/2, TP53, PTEN, APC, RB1, and VHL, among others [1]. These genes, when mutated, increase a patient’s predisposition to many types of cancer. 

This patient is a relative of mine. Fortunately, she is negative for all markers listed. When informed of this during her genetic consultation, she was visibly delighted. I was pleased to hear this as well, because, as her relative, this means I had a good chance of sharing the same negative markers.

However, as she was thankful for the knowledge of being negative for these markers, I realized that if the results came back positive, she would be in a vastly different scenario: she wouldn’t be relaxing during holiday visits with family, but instead worrying about an impending diagnosis. Instead of continuing on with her life, she would be living in fear that at any moment, one of her cells could turn cancerous, malicious.

While “genetic testing” today means identifying a predisposition for disease, it hasn’t always been that way. Nearly all infants at birth are tested for Phenylketonuria (PKU), or an enzyme deficiency in the metabolism of phenylalanine. If an infant has PKU, the family can start a diet low in phenylalanine immediately to prevent the symptoms of the disease; in contrast, a positive genetic test for a cancer marker leaves a patient to wait, often for decades, until symptoms show.

However, if a patient is diagnosed as having these markers, there are steps they can take to abate their risk. For a BRCA1 mutation, a woman can undergo a bilateral prophylactic mastectomy, a bilateral prophylactic salpingo-oophorectomy, or take chemopreventive drugs such as tamoxifen [3]. Although these greatly decrease the risk of disease, experts agree that “mutation testing of individuals who do not have cancer should be performed only when the person’s individual or family history suggests the possible presence of a harmful mutation” [4]. I agree with these experts for a few reasons.

The first and most important reason is informed consent. For starters, it’s highly unlikely for a patient to be knowledgeable enough about genetic testing to get tested or to understand their results unless they have advanced training in biology, medicine, or statistics. It’s not enough to indicate “positive” or “negative”; these tests are more nuanced than that. Of course, a positive marker increases a person’s risk for certain cancers, but it’s important to remember just that: your apparent risk increases. These genetic tests are not diagnoses, but rather predictions. Of course, one’s risk of getting a certain cancer was the exact same before and after he or she received the genetic test results; only after must the patient live with knowledge daily, often in fear that his or her cells become cancerous.

Furthermore, if a person tests positive for one of these markers, is he or she legally obligated to inform his or her family? Should the justice system subject the family of patients to undue stress that they may also have the marker? Is this appropriate for the public health system to do? There is already a precedent in HIV testing for these concerns; if a patient tests positive for HIV or AIDS, they are generally legally bound to inform their sexual partners or needle-sharing partners. [5]

Is it appropriate to inform children or parents that they may have a cancer-associated marker? I submit that it is not. Because a person does not choose what their genes say or who their parents are, they shouldn’t be obligated to the knowledge of a cancer marker; it makes sense in the case of HIV–people choose their partners, and can willingly put themselves at or protect themselves from risk. This idea is well summarized by Erez, et al. [6] and Takala [7] in the idea of the “right not to know”. These authors maintain that one of the paramount concerns in medicine is self-autonomy: “in a liberal society…the presumption of freedom [about one’s genetics] holds” [8]. In every case, patients who choose to undergo these tests may also choose to ignore the results; this choice must be respected at all costs.

Despite my concerns, I do recognize that genetic testing is an incredibly powerful tool that allows for early detection and treatment of cancer and other diseases. If a patient chooses to remain ignorant of the results for their own benefit, I believe it is the duty of the medical system, mainly the physician who is in charge of the care of the patient, to store this information and broach the issue when the clinician deems necessary (although, I will admit that the idea of a physician withholding health information from their patient is an uncomfortable precedent).

While genetic testing provides predictions of cancer or other genetic diseases later in life, it’s widespread use should be considered in the light of informed consent and the “right not to know”. Receiving a list of all negative markers may prove stress-relieving to a person’s psyche; however, testing positive for even one may subjugate that person to living in fear of a disease for the rest of their life.


1. For a more complete listing of commonly tested genetic markers, see “Genetic Testing for Hereditary Cancer Syndromes,” FactSheet, National Cancer Institute, accessed January 2, 2017,

2. “Phenylketonuria (PKU) Tests and Diagnosis,” Mayo Clinic, accessed January 3, 2017,

3. “BRCA1 & BRCA2: Cancer Risk & Genetic Testing,” cgvFactSheet, National Cancer Institute, accessed January 2, 2017,

4. Ibid.

5. “Legal Disclosure,” accessed January 2, 2017,

6. Ayelet Erez et al., “The Right to Ignore Genetic Risk in the Genomic Era - Prenatal Testing for Huntington Disease as a Paradigm,” American Journal of Medical Genetics. Part A 0, no. 7 (July 2010): 1774–80, doi:10.1002/ajmg.a.33432.

7. Tuija Takala, “The Right to Genetic Ignorance Confirmed,” Bioethics 13, no. 3–4 (July 1, 1999): 288–93, doi:10.1111/1467-8519.00157.

8. Ibid., 293.

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