When whole genome and whole exome sequencing are introduced into health care, and offered directly to consumers in commercial settings, the landscape of genetic testing will drastically change. The information that is obtained from sequencing is much more complex than the results of traditional genetic testing: where traditionally a test is undertaken to inform a single health outcome, genome sequencing can inform the diagnosis of, or susceptibility to, numerous diseases.

Genome sequencing is envisioned to ultimately replace conventional forms of genetic testing. This prospect has already led to an intense debate on what to do with the remaining unreported data, how to deal with issues around privacy, discrimination, insurability, and patient and consumer protection.

The opportunities for the return of incidental findings, discrimination and stigmatization depend on the predictive ability of a test. Therefore, the discussion of these concerns in the context of sequencing should start from a critical assessment of the predictive ability of DNA, which is paramount because the genome does not have an overall predictive ability as such. Rather, genome sequencing should be seen as one assay that consists of numerous tests. The predictive ability depends on what is predicted, in whom and how (using which specific information from the DNA).

For a constructive debate on ethical and societal issues, health care professionals, policy makers, legislators and the public need to be aware of the possibilities and limitations of sequencing. A good understanding of what can (and cannot) be predicted from our DNA is necessary to ensure a responsible introduction of genome sequencing in health care and an effective regulation of commercial DNA testing. This presentation provides a concise explanation on how DNA can be both predictive for some diseases and not predictive for others.