Not only are all men (and women) created equal, but we are all nearly identical, genetically-speaking. A team of geneticists at Stanford University conducted a survey comparing and contrasting more than 1,000 human genomes throughout the world and found that all humans were 99.9 percent biologically identical. The genetic differences that make us the unique individuals that we are occur only in 0.1 percent of our genetic material. Yet recent advances in the study of these small differences could have a big impact on improving medical treatments.
Medications interact with various systems in the body to produce a therapeutic effect. Analyses of the genes responsible for the structure and function of the targeted body system help predict who will benefit from treatment. Rather than giving everyone with a certain diagnosis the same dose of the same medication, medical therapy can be customized based on genetic analysis. This new field of medicine is called pharmacogenetics.
Customized health care might sound trendy and luxurious, but in many cases it can also be cost-effective. Genetic analysis is used in medicine, research, forensics and for tracing family ancestry. Such widespread use has led to a more streamlined approach to laboratory processing, making it more accurate and cost-effective. Using pharmacogenetics, genetic analysis is used to predict an individual’s capacity to process medications. Promptly identifying effective treatments saves time, pain, suffering, money and lives.
The utility of pharmacogenetics can be easily illustrated by examining the cytochrome P450 (P450) group of genes. The P450 genes are required to produce enzymes that help metabolize many different medications. Some people do not produce any such enzyme at all and others produce a lot. For example, a person with little or no P450 activity cannot convert the opiate codeine into morphine in the brain. Such a person will not experience any pain relief, but could very well experience side effects like constipation or nausea. This person would be categorized as a poor metabolizer on his or her genetic test. Anywhere from 1 to 30 percent of the population tested are poor metabolizers, with varying rates across ethnic groups.
Poor metabolizers are not the only ones who have to watch P450 enzyme activity levels. Others can be intermediate, extensive or ultra-rapid metabolizers. Ultra-rapid metabolizers produce a lot of enzyme and can have extreme effects all at once, putting them at risk for overdose.
The P450s are important for the metabolism of many commonly-used drugs, and drugs that require them to produce metabolic enzymes are called P450 substrates. Tamoxifen is a chemotherapeutic agent used to treat cancer and has many dangerous side effects. Poor metabolizers would not be good candidates for tamoxifen because it wouldn’t help the cancer but could make them very sick.
To further complicate the issue, certain medications affect the amount of enzyme the P450 genes can produce. Although the P450s are not sensitive to induction (enzyme production induced by other substances), it can be suppressed. In other words, certain substances can sometimes increase enzyme production, or they can decrease or inhibit it. Understanding how medications affect P450 enzyme production and underlying P450 function can help predict individual susceptibility and response to treatment combinations.
Many psychiatric medications used to treat depression, anxiety, psychosis and other forms of mental illness either require P450 to be effective or inhibit enzyme production. Some cardiac medications and allergy medications are also affected, as well as over-the-counter, illegal and other prescription drugs.
Other genetic variants have also been discovered to be important in the field of pharmacogenetics. Although more research is needed to further delineate how genetic composition affects different medications for different disorders, pharmacogenetics can serve as an important part of medical therapy for mental illness and substance abuse treatment.
Pharmacogenetic testing is now available at select treatment centers across the country. At Sovereign Health Group Treatment Centers, we strive to determine the most effective treatment programs using state-of-the-art science and technology, including pharmacogenetics. For more information about our programs, call (866) 819-0427.
By Dana Connolly, Ph.D., Sovereign Health Group writer