Direct-to-consumer (DTC) genetic tests give inaccurate predictions of disease risks and many European geneticists believe that some of them should be banned, the annual conference of the European Society of Human Genetics heard May 31....
Here's the abstract for the talk which argued that DTC companies don't give the best disease risk estimates:
Objective: Direct-to-consumer (DTC) companies predict risks of common complex diseases on the basis of genetic markers. Given the low number of markers involved and their small effect sizes, it is unclear whether high-risk groups can be identified. We investigated the risk distributions generated by two DTC companies for 8 diseases. Methods: We simulated genotype data for 100,000 individuals based on published genotype frequencies. Predicted risks were obtained using the formulas and risk data provided by the companies. Results: The table presents observed and trimmed ranges of predicted risks. The two companies used different formulas to calculate risks. One company predicted risks higher than 100% for 5 out of 8 diseases, which for AMD concerned 1 in 200 individuals. Observed ranges were smaller for the second company, except for Type 1 Diabetes. Predicted risks higher than 50% were frequently observed for company 1, but were exceptions for company 2. When predicted risks of company 1 were calculated using the formulas of company 2, observed ranges were substantially smaller.
Since I don't put much stock in the small effect disease risk predictions currently, I am not surprised. But I'd be curious to look at the guts of their results. This was presented at conference, so some caution has to enter into the picture. The main issue I'd always want to emphasize with critiques of the lack of efficacy of DTC is that they need to be evaluated against the baseline of the limits to the efficacy of medical professionals and medicine in general. Genomics and DNA doesn't make something magical, whether for good or ill. The second presentation covered in the ScienceDaily release is kind of more disturbing to me. Here's the abstract:
An increasing number of private companies are now offering direct-to-consumer (DTC) genetic testing services. The tests offered range from tests for single gene, highly penetrant disorders to susceptibility tests for genetic variants associated with common complex diseases or with particular non-health-related traits. The aim of this study was to collect information regarding the awareness, experiences and attitudes of European clinical geneticists about genetic tests and test interpretations sold directly to consumers. European clinical institutes where genetic counselling is offered to patients were contacted. One-hundred and thirty-one of the three-hundred eligible respondents (44%) answered a questionnaire. Eighty-six percent (110/128) of the clinical geneticists said they were aware that companies are advertising and selling genetic tests directly-to-consumers. Of the 44% (54/121) of the respondents who had been contacted by patients who underwent DTC testing, almost all respondents (98%, 47/48) did discuss test results with the patients. The following respondents somewhat or strongly agreed that DTC genetic tests should be legally banned for following tests: prenatal gender tests (69%, 77/112); genome scans (63%, 70/112), 54%, athletic performance (54%, 61/113), preconceptional carrier tests (53%, 59/112) and ancestry testing (27%, 30/113). The results indicate that most European clinical geneticists have only limited experience with patients who have accessed direct-to-consumer genetic testing, however, these physicians are entering into patient-physician interactions with patients when requested to do so.
I'm going to calm down, because these results frankly kind of piss me off. 30 out of 113 think ancestry testing should be legally banned? The stuff quoted in ScienceDaily is even more disturbing:
"
Genome-wide scans by companies are totally unacceptable, as they can derive sensitive information about medically relevant conditions and will also provide lots of information which is difficult to interpret, even for medical professionals
," said another respondent. Presenting the results of such tests directly to individuals is unacceptable, the majority of those surveyed said. 90% of respondents felt that a pre-symptomatic test -- predicting if an asymptomatic person had a very high probability of developing a condition -- should not be allowed without face-to-face medical supervision; 93% felt the same for a predictive test for a condition that has a penetrance (the proportion of individuals with the mutation who exhibit clinical symptoms) of 50 -- 60%; 79% for a carrier test for homozygous monogenic disorders, such as sickle-cell anaemia; and 72% for a predictive test for a condition that increased or decreased a person's risk of developing it by 4% when compared to the general population. At the moment, DTC genetic tests reach the market without having undergone any form of regulation. "Better regulation is needed at the level of market introduction of these tests," says Professor Borry. As in the case of drugs, a procedure should be developed for genetic tests.
I think one of the key issues is that these genetic professionals view DTC genomics in the same category as a pharmaceutical. I view DTC genomics as part of the same family of consumer and social goods as information technology. When viewed in the context of our current medical-industrial infrastructure it seems that on the margin the future opportunities to reduce morbidity through better lifestyle choices and more information via DTC genomics is a no brainer. If there was social science evidence that people who receive false positive results are regularly committing suicide then obviously my preference for loose regulation would need re-examination. That would be like someone jumping off the tenth floor of an office building after a "blue screen of death." But from what I've seen at places likes Genomes Unzipped and FuturePundit these dystopian visions of mass hysteria don't end up to panning out. Until that point it seems that the best avenue toward improvement of this technology is to allow the trial and error process of innovation to continue. It is incumbent on those of us "in the know" to evangelize about the limitations and opportunities of this technology (e.g., don't buy AIBioTech Sports X Factor!). But the reality is that much of medicine is already technology, and not subject to careful professional oversight. Instrumentation necessary for life critical functions are designed and built by engineers and technicians. The bigger social issue here seems to be the attempt by genetic professionals to regulate the flow of information. Though I'm skeptical of most licensing regimes I'm not totally opposed to them on principle. But they need to be imposed on extreme cases only. You don't want just any random person offering cut rate surgery or mass prescribing antibiotics to one and all. The individual and social costs of these actions can be very negative and irreversible (i.e., someone dies, or a resistant bacterial strain emerges). But when it comes to information services requiring a "professional" is going to choke the supply and spike up the cost. Additionally, there's going to be a constant latency in terms of the ability of professionals to actually interpret the swell of data which is going to be coming in their direction. The reality is that the professionals are going to have to rely on advanced analytic software. Obviously my own preference is that such analytic software should be widely available and cheap. If you want to ban sex selective abortions address the problem at the level of abortion, a procedure which most people agree should be under some professional and regulatory supervision already. Don't deny people the information to prevent a few harms. If anyone wants to release their genotype into the public domain, email me at contactgnxp -at- gmail.com. Know that some clinical geneticists probably think you're a public health hazard!
