Genes-R-Us — Direct-to-Consumer genetic testing: To better health or greater anxiety
Posted: Wednesday, October 26, 2011 5:01 pm
To “know,” or not to “know”: that is the question. Whether ’tis nobler in the mind to suffer the slings and arrows of outrageous “genes,” or to take arms against a sea of bad “DNA.”
My mercilessly-modified soliloquy of Shakespeare’s Hamlet, captures the dilemma of many people toward Direct-to-Consumer (DTC) genetic testing. Do I really want to know my genetic Achilles’ heel? Is “bad” DNA my destiny?
OK, so everyone is not as enthusiastic about DTC genetic testing as I am. Many objections are based on a misunderstanding of the interplay between genes and disease. Other concerns range from the potential loss of health insurance to the creation of designer babies.
The Genetic Information Nondiscrimination Act (GINA) of 2008 protects U.S. citizens from employment and health insurance discrimination based on genetic information. Note that GINA is silent about life insurance. What is our current health insurance baseline without any DTC genetic testing considerations? Woe to anyone taking an antidepressant who should try to purchase private health insurance.
Designer babies and the entire topic of genetic engineering is worthy of a whole column. But if we are to be an ethical society, we cannot afford to take the position that this genomics “stuff” is too complicated to understand. Consider the couple that chooses abortion because their unborn child has an amniocentesis-confirmed genetic condition called Down’s syndrome. What about infanticide in India because the baby was XX not XY? Where are we now as a society?
The highly revered scientific journal, Martha Stewart Living (November 2011) contains an article entitled, “Is Your DNA Your Destiny?” This “one-pager” touches lightly on epigenetics. Wow, genomics is mixed in with holiday desserts and decorations. I have died and gone to heaven.
Epigenetic scientists study things like how “good” versions of protective genes can be turned off by cigarette smoking or obesity, how riskier versions of genes may be mitigated or shut off by a healthy diet and exercise, or how these on/off genetic mechanisms gets passed onto subsequent generations even though the “letters” in the parental genome were not changed. (Yes, another whole column…)
Let’s begin with the disease and gene confusion. We hear the most about diseases like cancer (especially breast and prostate), heart disease, type-2 diabetes, auto-immune disorders and Alzheimer’s disease (AD). These are genetically complicated diseases in that no one can tell you — “Yes, you will get breast cancer because you harbor a ‘bad’ versions of the BRCA gene” or “No, you won’t get breast cancer because you are in the estimated 97 percent or higher group with the more protective versions of the BRCA gene.”
Most women who get breast cancer have protective versions of the BRCA gene, so what is going on here? Scientists are only beginning to understand which SNPs or other parts of our DNA increase the likelihood of our getting chronic or complex diseases. In genome-wide association studies, SNPs or other DNA features are associated with disease and then used to quantify disease risks across very large numbers of people.
Heart disease, type-2 diabetes and cancer are called polygenic diseases because multiple genes are involved. Most people are worried about the risk of their polygenic diseases. Although you will not get a yes or no answer from DTC genetic testing, I remain a strong proponent of DTC genetic testing because there is much we can do to improve our health in light of our test results.
My risk of age-related macular degeneration (AMD) is almost four times that of an average person. How I wish I had known this from an early age. I would have worn protective sunglasses and started lutein much earlier. Thankfully I have never first-hand smoked. But with my AMD genetic risks, I would have stopped immediately, as smoking is the biggest behavioral risk factor for AMD. My birth mother engaged in all the risks and none of the protection until she developed AMD. Her genetic risk is only half mine.
We hear some but worry less about diseases such as cystic fibrosis, sickle-cell anemia and Huntington’s disease (HD) if we are not personally impacted. There are a couple thousand of these monogenic disease types. Genetically, these are much simpler diseases as there is a single “bad” gene or “defect” to blame.
For some monogenic diseases, it is enough to inherit just one bad string of DNA “letters” from a single parent, as in the neuromuscular Huntington’s disease. But for other diseases, such as sickle-cell anemia or cystic fibrosis one needs an affected copy from each parent. DTC genetic testing provides carrier status on several dozen of these conditions. My birth father had no idea that he was a carrier of cystic fibrosis.
Legal efforts are already gaining momentum to “protect” you from the knowledge of your genome. Perhaps you better keep reading my columns to decide if that is really what you want.
Next week: How to interpret your disease risk numbers.
Editor’s note: Nancy Miller Latimer has worked in scientific research and development for 27 years. She blogs at neuronalbeauty.blogspot.com.
Published in The Messenger 10.26.11