Everyday there is a DNA genetic breakthrough. For some people, getting a DNA test can save them from wondering if they have a genetic disease, or have a likelihood to develop a disease, or even to know if they are a genetic carrier of a disease before deciding if they will have children. If you have a parent with Huntingtons, knowing if you are a carrier or if you will develop the disease is a mixed blessing. Do you want to know that you will face that kind of death. Is it better to know or not know? What about your maternal relatives having breast cancer? Of course it is better to know you have the breast cancer genes and have a high likelihood of cancer. Knowing, you can choose to have surgery to remove the risk.
Many diseases are multi factorial, meaning a lot of factors influence the outcome. You may need to have both environmental and genetic factors for the disease to show up. If people are worried about their results, they need to know what they are looking at. I have health reports at 23andme and Livewello. They list diseases I have one allel for, but not both, or 2 alleles for one gene but the disease, like Lupus for example, has 7 genes that influence the disease. I didn’t know if having 3 of 7 was bad or if I needed all seven to be worried about getting Lupus. I also received health reports telling me how I might respond to medicines, exercise, food, and more.
This article talks about whether or not test results makes a difference to people that have had DNA health testing. Knowing Your Risk Of Disease – does it make a diference?
Posted by Harriet Hall on August 23, 2016
Genetic variants may provide information you’d rather ignore
The complete sequencing of the human genome by the Human Genome Project was a remarkable accomplishment and a cause for celebration. Several companies including 23andMe, Navigenics, and deCODE have capitalized on that scientific achievement by offering genomic testing directly to the public. They promise more than they can deliver, and consumers don’t understand the limitations of the test results. The subject has been covered in several SBM articles.
One of the expected benefits of genomic testing is that if people knew they were at high risk of a disease, they would take preventive steps to reduce their risk. That seems plausible; but a recent study, a systematic review in the BMJ (formerly the British Medical Journal) calls that assumption into question. It found that communicating DNA-based disease risk estimates did not increase risk-reducing health behaviors or motivation to engage in such behaviors.
Futurist Ray Kurzweil predicted:
Genomics testing may soon be able to predict precisely what foods are best for us, prescribe individualized exercise and other lifestyle prescriptions, and recommend a personalized list of supplements, neutraceuticals [sic], and prescription drugs for maximum health and disease avoidance.
His prediction may be correct, but how soon is “soon?” We aren’t there yet, not by a long shot.
Current risk predictions are imprecise and are based on assumptions
We can’t be sure that the high-risk gene variants cause disease: all we really know is that a variant was statistically associated with a disease in the particular population tested, and correlation does not prove causation. It’s complicated. Many diseases are multifactorial. The expression of one gene may be affected by other genes and by environmental and lifestyle factors. Having a gene associated with a disease does not mean you will get that disease; the most it might do is increase the probability. And conversely, having variants associated with low risk is no guarantee that you won’t get the disease. And the different companies don’t even agree with each other; they assess risk using different combinations of “snips,” single nucleotide polymorphisms. To assess prostate cancer risk the different companies test for 5, 13, and 9 variants respectively, but no company tests for all 16 variants known to be correlated with increased risk.
Are we there yet?
For genomic testing in general and for assessing risks of various diseases, many experts have asked “are we there yet?” and have concluded that we are not. For example, the American Academy of Ophthalmology has advised physicians, outside of research studies, against genetic testing for eye disorders such as macular degeneration, “until treatment or surveillance strategies can be shown to be of benefit to individuals with specific, disease-associated genotypes.”
An article in the New England Journal of Medicine (NEJM) provides a good analysis of the pitfalls of genetic risk predictions; it is well worth reading. It says “We are still too early in the cycle of discovery for most tests that are based on newly discovered associations to provide stable estimates of genetic risk for many diseases.”
Another article in the NEJM just this month addressed genetic misdiagnoses of the risk of hypertrophic cardiomyopathy:
Multiple patients, all of whom were of African or unspecified ancestry, received positive reports, with variants misclassified as pathogenic on the basis of the understanding at the time of testing. Subsequently, all reported variants were recategorized as benign. The mutations that were most common in the general population were significantly more common among black Americans than among white Americans (P