Pharmocogenetics

A tipping point for personalized medicine

The mass marketing of genetic testing kits, such as Helix and 23andMe, suggests that our DNA can provide simple answers about our health. In reality, applying genetic knowledge to improve a patient’s health is much more complex.

For more than 20 years, CAMH has been at the forefront of bringing genetic testing from lab to clinic, to identify which medications are most likely to work for a given patient without side-effects. Physicians can use the results to select medications or adjust doses. Patients are spared trying one medication after another. “We have shown that we can create a practical, affordable and simple report that works,” says Dr. Daniel Mueller. Through the IMPACT study, led by Dr. James Kennedy, thousands of patients across Ontario have had genetic testing. The GeneSight test panel analyzes eight genes to provide information on 33 psychiatric drugs. It was developed by Assurex Health, which has a partnership with CAMH. For depression and anxiety, the test has been shown to reduce the severity of patients’ symptoms.

While the field seems to be approaching a tipping point—with pharmacies now selling genetic tests directly to customers—researchers caution that there is still a lot to learn.

At CAMH, powerful computing techniques such as machine learning are being used to validate and identify new genetic markers. There is potential to develop multi-gene risk scores to predict medication responses based on hundreds or even thousands of genes, which Dr. Mueller’s team is also applying to unravel the genetic underpinnings of aging and depression onset. Dr. Rachel Tyndale is expanding her research on gene-guided treatment for nicotine addiction into diverse populations that may metabolize drugs differently, such as Indigenous peoples and pregnant women. And the IMPACT study continues to build evidence to show that genetic testing is effective for patients, and more efficient and less costly for the health care system.