There are now several companies that offer genetic analysis to determine which variations of certain genes a patient may carry. Some of these genetic variations lead to possible changes in rates of drug metabolism, or in the signals within some of the body’s neurotransmitter systems. These companies claim that genetic testing can help to pick medications with better likelihood of success.
However, claims made by genetic testing companies are generally not reviewed by the FDA. Unlike the stringent rules that apply to pharmaceutical manufacturers, genetic testing companies enjoy great freedom in what they may claim. Claims made by pharmacogenetic testing companies are based on a much smaller body of evidence, and evidence of lower quality. Another key difference pertains to adverse effects and risks. Drug companies are required to look for, and report, adverse effects of their treatments. Genetic testing companies are under no similar obligation.
There are very little data on the value of genetic testing to select antipsychotic medication, or to guide its dosing. The rationale for gene-guided treatment is logical. And there are indeed clinical studies showing benefit.
On the other hand, it’s also possible that patients can suffer harm as a result of currently-marketed genetic studies. There have been several instances in which a company’s genetic report labeled a particular medication as ‘less desirable’ or ‘to be avoided’ when, in reality, those medications turned out to be the most helpful form of treatment. Based on a genetic report, patients have experienced longer-than-necessary delays in getting the most effective treatment.
I reviewed the status of pharmacogenetic testing as applied to the selection of medications for the treatment of schizophrenia and presented this information to the Schizophrenia Learning Community on 21 November 2017. Here is the PowerPoint file from the presentation.