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Pharmacogenomics Cheat Sheet
Your guide to understanding key PGx concepts, common gene-drug interactions, and clinical applications.
Key Concepts
| Term | Definition |
|---|---|
| Pharmacogenomics (PGx) | Study of how genes affect a person’s response to drugs. |
| Polymorphism | A variation in the DNA sequence (e.g., SNPs, insertions, deletions). |
| Genotype | The specific genetic makeup of an individual at a particular gene locus. |
| Phenotype | The observable characteristics of an individual, reflecting the interaction of genotype and environment. In PGx, it often refers to enzyme activity or drug response. |
| CYP450 | Cytochrome P450, a superfamily of enzymes crucial for drug metabolism, primarily in the liver. |
| Poor Metabolizer (PM) | Individuals with significantly reduced or absent enzyme activity, leading to slower drug metabolism. |
| Intermediate Metabolizer (IM) | Individuals with reduced enzyme activity compared to normal metabolizers. |
| Normal Metabolizer (NM) | Individuals with expected or typical enzyme activity. |
| Ultra-Rapid Metabolizer (UM) | Individuals with increased enzyme activity, leading to faster drug metabolism. |
| SNP | Single Nucleotide Polymorphism, a variation at a single position in a DNA sequence among individuals. |
Common Gene-Drug Interactions
| Gene | Drug | Effect of Polymorphism | Clinical Implications |
|---|---|---|---|
| CYP2C19 | Clopidogrel | PM: Reduced conversion to active metabolite. | Increased risk of cardiovascular events due to reduced antiplatelet effect. |
| CYP2D6 | Codeine | PM: Reduced conversion to morphine. UM: Increased conversion to morphine. | PM: Ineffective pain relief. UM: Risk of opioid toxicity, especially in children. |
| CYP2C9 & VKORC1 | Warfarin | Variations affect drug metabolism and sensitivity. | Increased risk of bleeding or clotting events; requires individualized dosing. |
| CYP2D6 | SSRIs (e.g., fluoxetine, paroxetine) | Variations affect drug metabolism. | Altered drug levels, potential for side effects or inefficacy; dose adjustments may be needed. |
| TPMT | Azathioprine | PM: Reduced metabolism of thiopurine drugs. | Increased risk of severe myelosuppression; requires dose reduction or alternative therapy. |
| UGT1A1 | Irinotecan | *28 allele: Reduced glucuronidation | Increased risk of severe neutropenia and diarrhea. |
Clinical Applications of PGx
- Personalized medicine: Tailoring drug therapy based on individual genetic profiles.
- Improved drug efficacy: Selecting drugs and dosages that are most likely to be effective for a patient.
- Reduced adverse drug reactions: Identifying patients at risk for adverse reactions and avoiding potentially harmful drugs.
- Optimized drug dosing: Adjusting drug dosages based on individual metabolism rates.
- Drug discovery and development: Identifying genetic factors that influence drug response.
Resources
- CPIC (Clinical Pharmacogenetics Implementation Consortium): cpicpgx.org
- PharmGKB (Pharmacogenomics Knowledgebase): pharmgkb.org
Disclaimer: This cheat sheet is for educational purposes only and should not be used for clinical decision-making. Always consult with a qualified healthcare professional for personalized medical advice.