What Do We Really Know About Genetic Testing?

Remy

Administrator
I think that the answer is pretty clear...not a whole heck of a lot. And certainly not enough to be presenting whole treatment plans as if they are based in scientific fact when clearly they are not. At this point, it is anecdotal science, which is certainly valuable but not necessarily predictive or exhaustive.

I have done the 23andme test and I found the results interesting and occasionally illuminating. However, we must be careful not to overstate the research when it is clearly still in its infancy. SNPs are very rarely predictive of dire consequences and the increased risk reported by these companies may often amount to absolutely nothing.

Regardless, I am all for continuing to explore this area. As the first article states, "it is likely that many of these limitations will be overcome". I look forward to that day.

All bolding is mine. Spacing added for clarity but the content has not been altered in any way.



There is considerable controversy over the sale and use of these tests, vocalized by medical and scientific professionals and consumer watch groups like GeneWatch (UK) and the Council for Responsible Genetics (USA).

Some of the concerns raised are summarized here:

(i) There is currently no adequate regulatory system for the sale and use of direct-to-consumer nutrigenetic tests. Consumers may fall victim to false or misleading advertising (Ries and Castle 2008).

(ii) The science of nutrigenetics is in its infancy so “personalized” nutrition advice generated by these tests is often very general or unproven (Hogarth et al. 2008).

(iii) Most health care practitioners are currently not well educated on the use of nutrigenetic testing for diagnostic or counseling purposes (Morin 2009).

(iv) “Medicalizing” the diet may cause normal healthy foods to be overlooked. Many companies use genetic testing results to advise clients to purchase specially designed, and often expensive, supplements (Goddard et al. 2007).

(v) The legal status of genetic material and information, as well as bioethical considerations surrounding genetic testing, are still heavily debated (Bergmann et al. 2008).

(vi) Little is known about the psychological ramifications of revealing to patients their genetic propensities to lifestyle related diseases.

As clinical research and regulatory bodies catch up with the demand for personalized health care and nutrition, it is likely that many of these limitations will be overcome. Until the science of nutrigenomics matures, however, eager consumers and entrepreneurs may be left to philosophize on the future of health care.

Alison Harvey offers the following revelation of the post-genomic age: With the advent of technologies such as nutrigenomics, wellness becomes an enhancement of our corporeality at the molecular level, our genetic functioning. Knowledge of the specific weaknesses in one's genome (provided by a nutrigenomic test) allows one to be more proactive in taking steps to counter that weakness, providing one's genome with the best possible environment to maximize its functioning (by following a personalized diet), so attaining a new state of health specific to one's genomic individuality. The quest for health is more than an individual responsibility; it is a route to selfrealization. [Harvey 2009]

At a time when our enthusiasm for nutrigenomics is matched only by our uncertainty of its consequences, we are faced with a long list of obstacles in making personalized nutrition and health a reality. The onus is not only on the researchers to continue churning out evidence of gene–nutrient interactions, but on the governing bodies who must navigate the uncharted waters of elective genetic testing and nutrigenomic marketing, and the social scientists and consumer watch groups tasked with monitoring the individual and societal responses to each new development.
This article discusses a range of direct, indirect and intangible social costs that might follow from this type of testing. So yes, there are risks associated with this type of work too.

A recent review of the genetic tests currently marketed online found that all but two of the gene–disease associations tested for were extremely modest, with odds ratios of up to 1.50 for elevated risk and down to 0.54 for protective effects.10

This has led critics to argue that the results of PGT provide virtually no clinically useful information about the risk of most diseases.10 Companies marketing PGT have also been accused of exaggerating its utility by ‘cherrypicking’ positive studies that demonstrate significant odds ratios for the genes in question8 and/or by referencing studies that have subsequently been shown to overestimate a gene–disease association which turned out to have no clinical utility at all (e.g. the use of CYP450 testing to guide the selection of antidepressant medication11).

Furthermore, a recent report raised serious questions about the quality of genetic tests being marketed for specific health conditions (e.g. age-related macular degeneration, Alzheimer’s disease, Crohn’s disease, hypertension, angina and sudden cardiac death) by showing that the same test revealed both above- and below-average risks depending on the company administering it..
Clin Genet. 2010 Feb;77(2):101-5. doi: 10.1111/j.1399-0004.2009.01291.x. Epub 2009 Nov 21.
Direct-to-consumer genetic testing: good, bad or benign?
Caulfield T1, Ries NM, Ray PN, Shuman C, Wilson B.
Abstract
A wide variety of genetic tests are now being marketed and sold in direct-to-consumer (DTC) commercial transactions. However, risk information revealed through many DTC testing services, especially those based on emerging genome wide-association studies, has limited predictive value for consumers. Some commentators contend that tests are being marketed prematurely, while others support rapid translation of genetic research findings to the marketplace. The potential harms and benefits of DTC access to genetic testing are not yet well understood, but some large-scale studies have recently been launched to examine how consumers understand and use genetic risk information. Greater consumer access to genetic tests creates a need for continuing education for health care professionals so they can respond to patients' inquiries about the benefits, risks and limitations of DTC services. Governmental bodies in many jurisdictions are considering options for regulating practices of DTC genetic testing companies, particularly to govern quality of commercial genetic tests and ensure fair and truthful advertising. Intersectoral initiatives involving government regulators, professional bodies and industry are important to facilitate development of standards to govern this rapidly developing area of personalized genomic commerce.
 

Cort

Founder of Health Rising and Phoenix Rising
Staff member
I think that the answer is pretty clear...not a whole heck of a lot. And certainly not enough to be presenting whole treatment plans as if they are based in scientific fact when clearly they are not. At this point, it is anecdotal science, which is certainly valuable but not necessarily predictive or exhaustive.

I have done the 23andme test and I found the results interesting and occasionally illuminating. However, we must be careful not to overstate the research when it is clearly still in its infancy. SNPs are very rarely predictive of dire consequences and the increased risk reported by these companies may often amount to absolutely nothing.

Regardless, I am all for continuing to explore this area. As the first article states, "it is likely that many of these limitations will be overcome". I look forward to that day.

All bolding is mine. Spacing added for clarity but the content has not been altered in any way.

This article discusses a range of direct, indirect and intangible social costs that might follow from this type of testing. So yes, there are risks associated with this type of work too.
I think this

A recent review of the genetic tests currently marketed online found that all but two of the gene–disease associations tested for were extremely modest, with odds ratios of up to 1.50 for elevated risk and down to 0.54 for protective effects.10

is probably really important. I wonder if most people using these tests are aware of how strong or modest the associations were between diseases and genes - or how good the studies were that established the associations in the first place.. I, for one, don't even know what an odds ratio is.

I can see how genetic testing companies would cherry pick studies to find the strongest associations.
 

Remy

Administrator
I, for one, don't even know what an odds ratio is.
So an odds ratio is a statistical measure designed to test whether or not an intervention is better, the same, or worse than a placebo, or control arm.
In this case, you might say that if one genotype has a 0.54 odds ratio for protective effects, that means that one would be 54% less likely to suffer from whatever disease is associated with that gene.

Sounds great, right? But here's the catch...the actual risk might be infinitesimal anyway so a 54% reduced risk is like saying half of essentially no risk at all.

Not nearly so dramatic if you know your 1% risk of getting a disease is only cut by half because the chances you were going to get it in the first place were minute. But that doesn't sell newspapers nearly as well as "Half the Risk!!". :(
 

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