6.1 Presymptomatic Genetic Testing
Eedy Mezer, MD; and Alex V. Levin, MD, MHSc, FRCSC
- To understand the issues to consider when addressing a request for predictive (presymptomatic) testing for genetic disease, such as the ability to treat the disease, the value added for patients by knowing their status as affected or not, and the value added for society by this knowledge and the potential harms
- To appreciate the ethical concerns created by predictive testing for genetic disorders in children, in particular, respect for the autonomy of the child
- To understand the uncertainties in predicting patient affectation status due to the limitations of currently available clinical and laboratory tools
- To appreciate the personal and social potential implications of molecular genetic testing for asymptomatic children
A 3-year-old boy is brought to the eye clinic by his parents. The child has no apparent eye problem. His 40-year-old father has retinitis pigmentosa (RP) with onset at approximately 20 years old when he experienced decreased night vision. The father now has much reduced peripheral vision, although his straight-ahead vision is still normal. Family history reveals three other affected family members, with a pedigree suggesting autosomal dominant inheritance. The parents ask, "Will our son get RP?"
- What are the considerations about the predictive test?
- What are the considerations about the disease?
- Are there potential harms from predictive testing?
- Are there special considerations for children?
- Is there policy or empirical research to guide the clinician?
- How can clinicians best proceed in a non-directive fashion?
The ocular genetics counsellor spoke with the parents of the 3-year-old boy and explained the potential risks and benefits of presymptomatic testing and the lack of known therapeutic or preventative interventions for RP. The child was reportedly entirely asymptomatic. With this information, the parents decided that there was no need for predictive testing.
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