Development of a Nation-wide Approach to Incidental Findings from Genome-wide Sequencing in Clinical Care

Julie Richer, Anne-Marie Laberge and Kym Boycott on behalf of the Incidental Finding Working Group of the Canadian College of Medical Geneticists

In recent years, the cost of DNA sequencing has declined rapidly. Next-generation sequencing technologies have made it possible to interrogate a patient’s genome in a cost-effective and efficient manner. While genome-wide sequencing in Canada has been performed on a research basis for several years, clinical diagnostic services based on these technologies are now becoming available and are increasingly being requested. Ensuring that patients with genetic disease have appropriate access to these diagnostic tests has, therefore, become important. Given that incidental findings are identified in 1-2% of tested individuals, the Canadian College of Medical Geneticists (CCMG) formed a working group to develop a responsible approach to incidental findings uncovered by such technology. The CCMG is a national professional organization comprised of clinically-trained medical and laboratory geneticists that establishes professional standards of clinical genetics practice across the country. The working group consisted of medical geneticists, clinical laboratory geneticists, genetic counsellors, ethicists, lawyers, and genetic researchers. The Statement was circulated for comment to the Canadian College of Medical Geneticists (CCMG) membership-at-large and, following incorporation of feedback, approved by the CCMG Board of Directors.

To responsibly manage limited resources in a publicly funded health care system and ensure optimal access to this technology for those who are most likely to benefit, whenever possible, genome-wide data should be filtered for genes known to be associated with the clinical presentation of the patient. For patients for whom a diagnosis cannot be uncovered with a filtered approach, a more detailed consent process is required prior to removing filters.

  1. Competent adults should be given the option to receive, or not, all clearly pathogenic variants regardless of their medical actionability.
  2. For incompetent adults, pathogenic medically actionable variants should be reported to their legal representative, unless the incompetent adult concerned expressed wishes to the contrary while still competent.
  3. In children, in order to protect their right to an open future including the right to choose which information they wish to learn and to protect their future insurability in a country where there is currently no genetic non-discrimination law, only pathogenic variant for conditions medically actionable in childhood should be disclosed and such variants should be disclosed regardless of the preference of the parents. A child’s risk for adult-onset genetic conditions should not be communicated unless (1) the parents request such disclosure, AND (2) disclosure of the information could prevent serious harm to the health of a parent or family member, as determined on a case-by-case basis.

Determining which conditions are considered clinically actionable is a challenge. Assessment of actionability during childhood should strongly consider, issues of penetrance at 18 years, likelihood of adverse outcome with this condition and whether a clear risk-reduction intervention with proven benefits is available should be strongly considered. For incompletely penetrant conditions, the likelihood of a diagnosis not being made or being sufficiently delayed to have a deleterious impact on the patient if we wait for them to display clinical symptoms should also be considered. Finally, in order to ensure that future patients have fair access to this technology, we do not recommend on-going re-interpretation of variants beyond the initial analysis unless explicitly requested by a geneticist still actively caring for such patient.