DNA Testing Advances Aid In Depression Treatment

Almost one third of Americans currently take antidepressant medications and many have had problems finding the right drug and dose. This is not surprising to people that study genetics - research shows that of all the clinical factors such as age, sex, weight, general health and liver function that alter a patient's response to drugs, genetic factors are the most important.


Psychological disorders are complex and the number of treatments available in the United States continues to grow, but virtually all medications used to treat depression are metabolized by two enzymes in the liver: CYP2D6 and CYP2C19. Your genes are the main factor determining the level of these enzymes- if you have too much of the enzyme, you process the medication too quickly, too little of the enzyme and the medication builds up in your bloodstream potentially causing adverse reactions or side effects. Without knowing your genetics, your physician may need to go through months of trial-and-error prescribing to find the right drug and dose for you.
Testing of CYP2D6 and CYP2C19 has been available for several years to help your healthcare provider optimize your response to antidepressants, but Genelex has just recently made another test available that can help maximize treatment success. The new test helps determine a person’s response to serotonin-selective reuptake inhibitors (SSRIs) which are among the most commonly prescribed antidepressants. This class of medications includes citalopram, fluoxetine, paroxetine and sertraline among others, and often is prescribed for depression or anxiety. As a class of medications, the SSRIs have shown successful responses for many people—but not in everyone.
There are a number of reasons why some people may respond better than others to this class of drugs. Each person’s unique genetic make-up affects how their body absorbs, modifies and ultimately excretes any medication taken, but genetics also play a role in how a drug will exert its effect within the body. Researchers have found that mutations in some genes specifically change how effectively SSRIs may act.
SSRIs are known to exert their effect, in part, by blocking the serotonin transporter. This transporter is found in regions of the brain where antidepressants are active. The transporter causes less efficient signaling in the brain by reducing the amount of active serotonin—an important chemical associated with mood response. When SSRIs block the transporter, more serotonin is available for signaling which can improve mood.
Researchers are studying the serotonin transporter (5HTT) gene to further understand its role in SSRI efficacy. In a DNA region (known as the ‘promoter’), very near the 5HTT gene, a mutation has been found that affects how well persons respond to SSRIs. This mutation results in a shortened form (allele) of the transporter gene.
The short allele is associated with less response to SSRIs. Patients who have the short allele are less likely to respond to SSRIs or may take longer to respond. This effect is often found in those who carry two copies of the short allele, but can also occur in those who have one short and one normal (long) allele. About 40% of the North American population carries the short allele.
Genelex Chief Scientific Officer Dr. Teresa Aulinskas stated, "I am excited to give medical providers another tool that will help them better target therapy in the treatment of depression when finding the right drug and dose as early as possible is so critical." Many people with depression get better with standard treatments — medications and psychotherapy — and return to enjoying a happy, fulfilling life. However, for a significant percentage of people, depression treatment just doesn't work, and they continue to feel sad and hopeless, disinterested in activities, and perhaps even suicidal. DNA testing may offer the key to avoiding this in many cases.
To help healthcare providers utilize DNA Drug Safety testing to cater dosage and drug selection to a patient’s individual needs, Genelex includes a free 90-day subscription to our personalized medication management software, GeneMedRx, with each DNA Drug Safety test order. This online tool helps healthcare providers predict drug-drug and drug-gene interactions so medication regimens can personalized.

To learn more about the use of DNA Testing in the treatment of depression, visit http://www.healthanddna.com/drug-safety/depression.html.