Pharmacogenetics at CAMH

At CAMH, we’re moving toward personalized and precision medicine by using our unique and individual genetic information to provide practical and affordable treatment guidance. The Pharmacogenetics Research Clinic at CAMH started in 2009, focusing on pharmacogenetic testing to optimize drug therapy and realize precision medicine in psychiatry. Patients were referred to our clinic to test their CYP2D6 and CYP2C19 liver enzyme gene variants to optimize their drug therapy for underlying mood or psychotic disorders, such as depression and schizophrenia.

The video below briefly explains the concept and importance of pharmacogenetics.

What happens next?

Our clinic received patient referrals for individuals experiencing inadequate response or intolerable side effects after treatment with antidepressant or antipsychotic medications. After conducting evidenced genetic testing, patients and their referring physicians received a report with their genetic metabolizer status and recommendations on which medications to avoid due to suspected poor metabolism of medications.

What did we find?

Overall, we detected that individuals with reduced drug metabolism profiles were more likely to have poor drug therapy outcomes for either or both of the CYP2D6 and CYP2C19 liver enzyme genes. Physicians were later asked to provide feedback through our developed “Pharmacogenetics in Psychiatry Follow-up” (PIP-FQ) questionnaire. The reports were ‘very well understood’ by physicians demonstrating the overall feasibility of pharmacogenetic implementation in clinical practice. 

Moreover, the feedback provided by physicians and patients has been very favourable, suggesting that pharmacogenetic testing improves treatment with no harm or negative experiences reported by patients (for details, see Müller et al., 2013; Walden et al., 2015 and Walden et al., 2019).

In the second phase of the study, additional genes were tested for research purposes. Our study integrated with the larger IMPACT trial with more than 11,000 patients tested (for details, see Herbert et al., 2018). Again, we found a high number of individuals with poor drug metabolism profiles suggesting that patients are more likely referred for genetic testing if they had experience poor drug therapy outcomes in the past due to their genetic makeup.

Guidelines for pharmacogenetics

Our group has regularly published articles reviewing the current evidence and recommendations for the use of pharmacogenetic information in clinical practice to promote personalized medicine (for details, see Read More). The most recent review is based on the consensus of a large group of investigators who initiated this work as part of the Genetic Testing Taskforce of the International Society of Psychiatric Genetics (ISPG; for details, see Bousman et al., 2020).

READ MORE

1. Psychiatric Genomics Research Network (PGRN)

2. Clinical Pharmacogenetics Implementation Consortium (CPIC) - Overview of CPIC (PDF)

3. PharmGKB: A pharmacogenomics knowledge resource.