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Houston, Texas

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Medical Genetics Test Details

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Cytochrome P450 2C19 (CYP2C19) Genotyping
Test Information: CYP2C19 is one of the cytochrome P450 enzymes that are responsible for much of Phase I drug metabolism. CYP2C19 metabolizes approximately 15% all prescribed drugs including clopidogrel (Plavix), mephenytoin, diazepam, propranolol, and omeprazole. Genetic variants associated with altered CYP2C19 activities have been identified and are relatively common in most populations. Individuals with nonfunctional/reduced function alleles in their CYP2C19 gene have much decreased CYP2C19 enzyme activity, which may result in adverse drug reactions or decreased drug efficacy.

The anti-platelet drug clopidogrel (Plavix) is metabolized by CYP2C19 and other enzymes in the liver to an active form. Patients with non-functional/reduced function alleles who were treated with clopidogrel had a higher rate of residual platelet aggregation and cardiovascular adverse events. In addition, recent studies indicate that the *17 allele is associated with increased CYP2C19 activity and increased risk for bleeding.

This analysis tests 9 different variants associated with altered CYP2C19 activity.

Reasons for Referral:
Evaluating genetic factors affecting drug metabolism for patients taking drugs metabolized by cytochrome P450 2C19, such as clopidogrel.
Test Details
Test Code: 6870
Test Includes: Variant alleles tested:

2 (c.681G>A): No activity
3 (c.636G>A): No activity
4 (c.1A>G): No activity
6 (c.395G>A): No activity
7 (IVS5+2T>A): No activity
8 (c.358T>C): No activity
9 (c.431G>A): Decreased activity
10 (c.680C>T): Decreased activity
17 (c.-806C>T): Increased activity


Special Notes: Limitations:
1. Not all variants with known impact on enzyme expression and activity are tested in this assay.
2. Non-genetic factors, variations in the other genes involving the drug metabolism are not measured by this assay.
3. Rare genetic alterations at primer binding sites may result diagnostic errors.

You must read, initial and include this form with your sample: CYP2C19 Informed Consent
Technical Information
Methodology: This analysis incorporates DNA amplification by multiplex PCR, allele specific primer extension, microarray hybridization and Fluorescence signal detection.
Gene Name: CYP2C19
References Values or Ranges: Analytical Sensitivity and Specificity: Greater than 99%
Sample & Shipping Information
Test Requisition: Molecular Diagnostics
Specimen Type: Blood
Requirements: Draw blood in an EDTA (purple-top) tube(s) and send 3 cc (Adults)
Shipping Conditions: Ship at room temperature in an insulated container by overnight courier. Do not heat or freeze.

Specimen Type: Saliva
Requirements: Collected with Oragene DNA Self-Collection Kit (provided by MGL with instruction).
Shipping Conditions: Ship at room temperature in an insulated container by overnight courier. Do not heat or freeze.

Turn Around Time: 10 days
Billing Information
List Price: *For Insurance or Institutional Prices, please call.
CPT Codes: 81225x1


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