DNA Drug Sensitivity Testing™ for
Depression Medications

Genelex will be happy to mail information to you or to your healthcare provider on your behalf, simply complete the request form.

Are you taking or considering antidepressants?

Have you experienced side effects?

Has the medication not had the desired effect?

If you answered yes to any of these questions, you are not alone. 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 account for a significant proportion.

Virtually all medications used to treat depression are metabolized by two enzymes in the liver: CYP2D6 and CYP2C19. Additionally, response to a group of commonly prescribed antidepressants called serotonin-selective reuptake inhibitors (SSRIs) is affected by the serotonin transporter, 5HTT or the pathways CYP1A2 or NAT2. Genelex refers to testing of these enzymes as DNA Drug Sensitivity Testing™ also known as pharmacogenetic testing. Your genes are the main factor determining the level of these enzymes in your liver- 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.

Population Frequency of Cytochrome P450 (CYP) Metabolizer Types

Partial List of Affected Medications

Now your healthcare provider can help optimize your response to antidepressants and many other medications by ordering DNA testing. Your results will be entered into our personalized medication management software, GeneMedRx. You or your healthcare providers can log in to see if current or future medications are predicted to cause drug-drug or drug-gene interactions so dosage and selection can be catered to your needs. You receive a 90-day subscription free with your testing; additional one year extensions are available for a nominal fee. Of course, your DNA never changes so the testing only needs to be done once in a lifetime.

Click here to view a list of drugs for which DNA testing may be helpful.

The Testing Process

The process is simple. You can order testing directly if you have a physician prescription or your healthcare provider can request testing for you. We send a cheek swab collection kit with directions by mail. Samples are submitted using the enclosed return mailer and results are provided in ten days or less. Faster testing is available for an additional charge. Call a DNA testing consultant at (800) 523-3080 for details and to order, or request information to you or to your healthcare provider on your behalf, simply complete the request form.

References

http://www.medscape.com/viewarticle/508543_2

Oesterheld, Jessica, M.D. GeneMedRx Drug Metabolism Tables

Aynacioglu AS, et al. Frequency of cytochrome P450 CYP2C9 variants in a Turkish population and functional relevance for phenytoin. Br J Clin Pharmacol 1999; 48(3):409-415

Scordo MG, et al. Genetic polymorphism of cytochrome P450 2C9 in a Caucasian and a black African population. Br J Clin Pharmacol 2001; 52(4):447-450.

Goldstein JA, Ishizaki T, Chiba K, de Morais SM, Bell D, Krahn PM, Evans DA. Frequencies of the defective CYP2C19 alleles responsible for the mephenytoin poor metabolizer phenotype in various Oriental, Caucasian, Saudi Arabian and American black populations. Pharmacogenetics 1997, 7: 59-64

Blaisdell J, et al. Identification and functional characterization of new potentially defective alleles of human CYP2C19. Pharmacogenetics. 2002 Dec;12(9):703-11

Ibeanu GC,  et al. Identification of new human CYP2C19 alleles (CYP2C19*6 and CYP2C19*2B) in a Caucasian poor metabolizer of mephenytoin. J Pharmacol Exp Ther. 1998 Sep;286(3):1490-5.

Ibeanu GC, et al. An additional defective allele, CYP2C19*5, contributes to the S-mephenytoin poor metabolizer phenotype in Caucasians. Pharmacogenetics. 1998 Apr;8(2):129-35.

De Morais SM, Wilkinson GR, Blaisdell J, Nakamura K, Meyer UA, Goldstein JA, The major genetic defect responsible for the polymorphism of S-mephenytoin metabolism in humans. J Biol Chem. 1994 Jun 3;269(22):15419-22

Ferguson RJ, De Morais SM, Benhamou S, Bouchardy C, Blaisdell J, Ibeanu G, Wilkinson GR, Sarich TC, Wright JM, Dayer P, Goldstein JA. A new genetic defect in human CYP2C19: mutation of the initiation codon is responsible for poor metabolism of S-mephenytoin. J Pharmacol Exp Ther. 1998 Jan;284(1):356-61.

Xiao ZS, Goldstein JA, Xie HG, Blaisdell J, Wang W, Jiang CH, Yan FX, He N, Huang SL, Xu ZH, Zhou HH. Differences in the incidence of the CYP2C19 polymorphism affecting the S-mephenytoin phenotype in Chinese Han and Bai populations and identification of a new rare CYP2C19 mutant allele. J Pharmacol Exp Ther. 1997 Apr;281(1):604-9.

Cozza KL, Armstrong SC, Oesterheld JR (2003) Drug Interaction principles for Medical Practice. American Psychiatric Publishing Inc

Kirchheiner J, Rodriguez-Antona C. Cytochrome P450 2D6 genotyping: potential role in improving treatment outcomes in psychiatric disorders. CNS Drugs. 2009;23(3):181-91

Seeringer A, Kirchheiner J. Pharmacogenetics-guided dose modifications of antidepressants. Clin Lab Med. 2008 Dec;28(4):619-26.

Kirchheiner J et al. Pharmacogenetics of antidepressants and antipsychotics: the contribution of allelic variations to the phenotype of drug response. Molecular Psychiatry 2004;9:442-473.

Cascorbi, et al. Arylamine N-acetyltransferase (NAT2) mutations and their allelic linkage in unrelated Caucasian individuals: correlation with phenotypic activity. Am J Hum Genet. 1995 Sep;57(3):581-92.

Note: Testing requires a prescription from a physician.