Most gene test sales are misleading

To the editor:

An editorial in your July issue criticized the medical community for being out of step with direct-to-consumer genomics and its potential to empower individuals' role in their own healthcare1. The problem sidelined by your editorial is that the genetic information currently provided is—as you concede—nearly all, to varying degrees, inaccurate, misleading or merely useless. Past 'genohype' and vested interests have also made consumers vulnerable to such misleading genetic information.

The idea of screening smokers' genes was first proposed by the tobacco industry, who wanted to identify the supposed one in ten who are genetically susceptible to lung cancer on the (false) premise that the rest of the population could then smoke with impunity2. There is no scientific basis to this idea because no twin study has ever found a significant inherited component to lung cancer. In addition, smoking causes multiple diseases so smoking with impunity is not an option. Subsequently, the pharmaceutical industry identified medicating the genetically susceptible 'pre-symptomatic patient' as a way to make more money3, but this does not mean this is necessarily an effective, or a cost-effective, way to prevent ill-health4. More recently, the food industry has promoted the idea of 'personalized nutrition' both as a marketing strategy for new 'functional food' products and as a means to shift the spotlight away from unhealthy product lines and practices.

In this sea of vested interests, it is important to ask whether people will be sold useful or reliable information from all or parts of their own genome, and whether an unlimited supply of unregulated, contradictory 'genetic information' is really such a good idea for health.

The benefits and risks of taking genetic tests are critically dependent on whether the risk information is reliable and has adequate predictive value (the 'clinical validity' of the test) and whether it is useful to decide who should take the proffered advice (the test's 'clinical utility')5. A recent critical appraisal of commercially available genomic profiles found significant associations with disease risk for fewer than half of the 56 genes used to assess health risks and personalize health interventions6. There was also a lack of information about multiple genes and gene-gene interactions, and no reliable data on gene-diet interactions. No gene-diet interaction means that the test performs no better than random selection as a means to tailor dietary advice7.

Recent studies, although confirming statistical associations between some genetic polymorphisms and common diseases, have shown very limited predictive value or clinical utility. For example, nine genes showing replicated associations with type 2 diabetes explain only a very small proportion of the aggregation of this condition in families and testing for these genes does not appear to improve prediction of type 2 diabetes compared with measuring existing risk factors (body mass index and fasting plasma glucose concentration)8,9.

It is true that the medical profession alone cannot act as reliable gatekeepers for genetic information. Without a regulatory appraisal, clinicians may well have no better idea than patients about the meaning of genetic test results. However, in addition to the counseling requirements that you note, the new Protocol to the Council of Europe's Convention on Human Rights and Biomedicine requires criteria for clinical validity and utility to be met before genetic testing services are offered10. Revision of Europe's Medical Devices Directives in line with the Protocol would therefore protect consumers from misleading claims made by genome sequencing companies: something geneticists should welcome, not oppose.

References

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    Janssens, A.C. et al. Am. J. Hum. Genet. 82, 593–599 (2008).

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    Council of Europe. Additional Protocol to the Convention on Human Rights and Biomedicine, Concerning Genetic Testing for Health Purposes. (Council of Europe, Brussels, 2008). http://conventions.coe.int/Treaty/EN/Treaties/Html/TestGen.htm

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Wallace, H. Most gene test sales are misleading. Nat Biotechnol 26, 1221 (2008). https://doi.org/10.1038/nbt1108-1221

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