Clinical Implementation and Outcomes of Genetic Testing for Epilepsy by the Ontario Epilepsy Genetic Testing Program

Epilepsy is a relatively common condition that affects approximately 4-5 per 1000 individuals in Ontario, Canada. While genetic testing is now prevalent in diagnostic and therapeutic care plans, optimal test selection and interpretation of results in a patient-specific context can be inconsistent and provider dependent.

The first of its kind, the Ontario Epilepsy Genetic Testing Program (OEGTP) was launched in 2020 to develop clinical testing criteria, curate gene content, standardize the technical testing criteria through a centralized testing laboratory, assess diagnostic yield and clinical utility and increase genetics literacy among providers.

Here we present the results of the first two years of the program, demonstrating the overall 20.8% diagnostic yield including pathogenic sequence and copy number variation detected by next-generation sequencing panels. Routine follow-up testing of family members enabled the resolution of ambiguous findings. Post-test outcomes were collected as reported by the ordering clinicians, highlighting the clinical benefits of genetic testing.

This programmatic approach to genetic testing in epilepsy by OEGTP, together with engagement of clinical and laboratory stakeholders, provided a unique opportunity to gather insight into province-wide implementation of a genetic testing program.