Personalizing Medicine: Toward Individual Genetic Profiles as Predictors of Drug Effectiveness

Steven G. Potkin, M.D. - Brain & behavior research expert on genetics
Steven G. Potkin, M.D.

From The Quarterly, Spring 2011

In the future and to some limited extent today knowledge of a person’s genetic background will help to determine their medical treatment. Genes will predict whether a drug will work for that individual, or cause a serious side effect, without the costly and sometimes dangerous process of trial and error.  Already, genetic information combined with new types of brain imaging is giving neuroscientists unprecedented access to the brain’s structure and functioning, allowing them to define areas important to understanding normal brain function and mental illness. This new knowledge will help them develop better drugs faster.

Researchers are applying gene studies and imaging to a variety of projects involving gene discovery and drug testing. One study they conducted identified schizophrenia patients who had a heightened genetic risk for developing tardive dyskinesia, a condition of involuntary facial tics that can be a troubling side effect of some antipsychotic drugs. Researchers were further able, with imaging technology, to pinpoint the regions of the brain that tardive dyskinesia affected.

A new technology called genome-wide association study (GWAS) now makes it possible to view entire genomes at one time. Iloperidone (Fanapt) is a new antipsychotic drug recently approved by the Food and Drug Administration. Before approval, researchers performed a genome wide scan of 250,000 single nucleotide polymorphisms, or SNPS, (pronounced ‘snips’). These are tiny variations in a gene’s composition from one individual to another. They found six variations out of the 250,000 scanned that predicted positive response to the drug.

A drug may be effective, but cause serious side effects. Some of these effects may be rare, but nonetheless the drug may be taken off the market unless prediction can be made as to who will be affected.  Another study has focused on the debate surrounding whether antidepressants cause suicidal thinking. In the study, adult patients with depression were given the antidepressant citalopram (Celexa). Some of the patients did develop suicidal thoughts. All of those had two particular gene variations. Based on this finding, risk of suicidality can now be predicted, at least in these instances, in advance.

Among many other explorations, researchers recently identified two schizophrenia related genes and their activity in the brain, as well as a gene for elevated Alzheimer’s disease risk. The lab has also been testing the effectiveness of a drug for Alzheimer’s based on patient genotypes, their individual gene profiles.

Steven G. Potkin, M.D.
Scientific Council Member
University of California, Irvine

In partnership with University of California, Irvine


Discovery to Recovery through Science

More than 40 institutions across the United States and Canada partnered with NARSAD, now Brain & Behavior Research Foundation, in presenting its “Healthy Minds Across America” series of public talks in 2010. Each event helped to bring science to families seeking hope for better treatments of a broad range of mental illnesses. The following pages contain highlights of presentations from various venues in the series. Full transcripts of the talks are available at Click “Past Research Events.”