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Brian
Not responding to common antidepressants: Pharmacogenetics or Compliance?

Brian is not responding to either Nortriptyline or Desipramine

• A look at our Pharmacogenetics Drug List reveals that CYP2D6 is the relevant gene to be tested by the laboratory.
• The genotype results from the laboratory indicate that this patient has more than two functional copies of the CYP2D6 gene and therefore is an ultra-rapid metabolizer.
• The Signature Genetics™ report provides a comprehensive overview of the scientific literature for CYP2D6 ultra-rapid metabolizers medicated with Nortriptyline and Desipramine. Serum levels of these two antidepressants have been shown to be subtherapeutic during standard dose therapy.
• The report also provides detailed and referenced information for the metabolism of each drug. This section can be used to understand CYP450-based drug-drug interactions.
• The drug-gene metabolism section of the Signature Genetics™ report would indicate to the physician if there is published scientific evidence for improved clinical outcome for CYP2D6 ultra-rapid metabolizers like Brian with upward dose adjustments of these drugs, or, if higher than normal levels of drug metabolites are associated with adversity in these individuals. This information can be used by the physician to help him/her make more informed decisions about Brian's therapy.

Mike
Considering blood glucose lowering therapy with Glyburide

Glyburide is found on our Pharmacogenetics Drug List. This indicates that clinical outcome with this medication has been shown in the literature to be influenced by CYP450 genetic variants. The Signature Genetics™ report may therefore provide valuable information for Mike's physician to consider before initiating therapy.

• The Pharmacogenetics Drug List identifies CYP2C9 as the gene to be tested by the laboratory for Glyburide.
• Mike's genetic test from the laboratory reveals that he has the CYP2C9 *1/*3 genotype.
• From the medical literature, the CYP2C9 *1/*3 genotype (identified as an extensive metabolizer diminished [EM dim]) is associated with diminished metabolic clearance of glyburide.
• This information becomes even more important when considering that the prevalence of this genotype (EM dim but also referred to in the literature as "intermediate metabolizers") for CYP2C9 is approximately 38% in the Caucasian population.

Martha
Will be undergoing surgery with an eventual need for Codeine and Warfarin

Martha's physician is looking to Signature Genetics™ for pharmacogenetic information relating to two medications that she may need after surgery namely, Codeine for pain relief and Warfarin for the prevention of thrombosis.

• The Signature Genetics™ report will indicate that Codeine's metabolism, to its pharmacologically active metabolite morphine, is dependant on CYP2D6.
• For Warfarin, the report identifies CYP2C9 as a key metabolic pathway.
• Martha's genetic results from the testing laboratory reveal that she is a PM (poor metabolizer) for CYP2D6 and an IM (intermediate metabolizer) for CYP2C9.
• Her Signature Genetics™ report details information indicating that CYP2D6 poor metabolizers cannot convert codeine to its active form and therefore do not experience the desired analgesic effect with this drug.
• Martha has one functional copy of the CYP2C9 gene and one partially-functional copy. Like 38% of Caucasians with this CYP2C9 genotype, Martha's warfarin dose requirements, according to the published literature, may be lower. This information from the scientific literature appears in the Signature Genetics™ report for the physician to consider.

Chris
Drug-Induced cytochrome interactions: Converting a standard metabolizer (EM) into a poor metabolizer (PM).

Chris is experiencing adverse drug reactions with Atomoxetine and Paroxetine.

• Genetic testing results from the laboratory in combination with the Signature Genetics™ report reveal that Chris is an extensive metabolizer (EM) for CYP2D6.
• According to the scientific literature, drug-related adversity has not been associated with CYP2D6 extensive metabolizers on either drug administered alone.
• However, in the drug-drug Interaction section of the Signature Genetics™ report there is documented evidence to show that Paroxetine, a potent inhibitor of CYP2D6, can indeed inhibit Atomoxetine's metabolism and clearance.
• The scientific literature shows that clearance of atomoxetine, if taken with paroxetine, may proceed at the same rate from a CYP2D6 extensive metabolizer as it would from a poor metabolizer.