pharmacogenomics 1-Dr P

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Questions and Answers

What is the significance of variation in response to medication?

  • It only affects clinical outcomes
  • It leads to improved individual and societal outcomes
  • It has no impact on individual and societal outcomes
  • It has a significant personal, clinical, and economic impact (correct)

What percentage of UK hospital admissions are attributed to adverse drug reactions (ADRs)?

  • 15%
  • 3.5%
  • 6.5% (correct)
  • 10%

What is the cost to the taxpayer due to adverse drug reactions (ADRs) in the UK?

  • £500 million
  • £1 billion (correct)
  • £750 million
  • £1.5 billion

What percentage of ADRs are considered avoidable?

<p>70% (C)</p> Signup and view all the answers

What is the cornerstone of medical ethics related to adverse drug reactions (ADRs)?

<p>&quot;primum non nocere&quot; first, do no harm (D)</p> Signup and view all the answers

What do adverse drug reactions (ADRs) include?

<p>Undesirable side effects (D)</p> Signup and view all the answers

Which factor is considered in the NHS strategy when deciding which gene-drug associations to incorporate into clinical practice?

<p>Clinical benefit (D)</p> Signup and view all the answers

What are the different metaboliser phenotypes that can result from differential metabolism by CYPs?

<p>Ultrarapid, intermediate, poor, and extensive metabolisers (D)</p> Signup and view all the answers

Which drugs are broken down by the liver enzyme CYP2D6?

<p>Antidepressants, antiarrhythmics, and antipsychotics (C)</p> Signup and view all the answers

How many variant alleles of CYP2D6 have been described?

<p>Over 70 (A)</p> Signup and view all the answers

What effect does genetic variation in CYP2D6 have on codeine metabolism for poor metabolizers?

<p>Failure to effectively convert codeine into morphine (A)</p> Signup and view all the answers

Which drug interacts with CYP2C9 and VKORC1, necessitating correct dosing based on individual genetic makeup?

<p>Warfarin (A)</p> Signup and view all the answers

What is the purpose of genetic testing before prescribing azathioprine?

<p>To determine the patient's response to the drug based on their genetic makeup (A)</p> Signup and view all the answers

Which protein plays a crucial role in influencing the response to certain medications like antidepressants and statins?

<p>ABCB1 (B)</p> Signup and view all the answers

What role do cytochrome P450 genes (CYP2D6, CYP2C19, CYP3A4) play in pharmacogenetic testing for psychiatric medications?

<p>Evaluating the patient's metabolic capacity for drug activation and inactivation (D)</p> Signup and view all the answers

In the context of pharmacogenomics, what is the significance of variants in ABCB1?

<p>They impact the patient's response to various medications (C)</p> Signup and view all the answers

What is the primary focus of point of care testing (POCT) in community pharmacies as highlighted by the NHS Long Term Plan?

<p>Diagnosis and monitoring of chronic diseases (D)</p> Signup and view all the answers

How does pharmacogenomic testing contribute to cost saving and increased drug adherence?

<p>By personalizing treatment regimens based on genetic profiles (A)</p> Signup and view all the answers

Which genes are primarily involved in immune-mediated adverse drug reactions (ADRs)?

<p>HLA-B, HLA-A, HLA-C (C)</p> Signup and view all the answers

What impact do genetic variants across different ethnic groups have on drug metabolism?

<p>They may affect drug efficacy and safety differently across ethnicities (C)</p> Signup and view all the answers

What is the primary goal of pharmacogenomics in personalized prescribing according to the NHS Long Term Plan?

<p>To optimize treatment outcomes through tailored medication approaches (A)</p> Signup and view all the answers

What is the role of cytochrome P450 genes in drug metabolism across different therapeutic areas?

<p>They play a crucial role in activating and breaking down medications in the body (D)</p> Signup and view all the answers

What percentage of UK hospital inpatients experience adverse drug reactions (ADRs) during their stay in hospital?

<p>15% (A)</p> Signup and view all the answers

Why is the integration of pharmacogenomics into routine NHS practice considered a goal?

<p>To provide safer and more appropriate therapies for patients (D)</p> Signup and view all the answers

What does pharmacogenomics aim to achieve in terms of drug dosing?

<p>Tailored prescriptions and dosages to individual's genes (A)</p> Signup and view all the answers

What is the difference between pharmacogenetics and pharmacogenomics?

<p>Pharmacogenomics examines how single gene variations affect drug responses, while pharmacogenetics explores how an individual's entire genome regulates drug responses. (B)</p> Signup and view all the answers

What aspect of drug response does pharmacokinetics describe?

<p>Absorption and distribution of drugs in the body (C)</p> Signup and view all the answers

How does DNA variation influence an individual's ability to respond effectively to a particular drug?

<p>By influencing the body's ability to break down or respond effectively to the drug (B)</p> Signup and view all the answers

What is the primary focus of pharmacodynamics?

<p>Molecular effect of drugs on their targets (A)</p> Signup and view all the answers

Why is prioritizing gene-drug pairs for implementation an important step for the NHS?

<p>To reduce ineffective or harmful treatments (C)</p> Signup and view all the answers

What percentage of adverse drug reactions (ADRs) are considered avoidable?

<p>70% (C)</p> Signup and view all the answers

What is the goal of integrating pharmacogenomics into routine NHS practice?

<p>To provide safer and more appropriate therapies for patients (A)</p> Signup and view all the answers

What does pharmacogenomics enable in terms of medicines optimisation?

<p>Informing medicine selection (A)</p> Signup and view all the answers

Which gene variant is associated with an increased risk of hypersensitivity reactions to Abacavir?

<p>HLA-B*1502 (A)</p> Signup and view all the answers

What type of reactions can HLA-B gene variants play a role in, particularly in relation to carbamazepine?

<p>Hypersensitivity reactions (A)</p> Signup and view all the answers

Which gene variant is more prevalent in Northern European populations and is associated with a broader range of carbamazepine-induced hypersensitivity reactions?

Signup and view all the answers

Which gene variant is implicated in causing irreversible hearing loss in response to gentamicin use?

<p>MT-RNR1 (D)</p> Signup and view all the answers

What type of testing has reduced the incidence of hypersensitivity reactions to Abacavir in real-world clinical practice?

<p>Pharmacogenomics testing for HLA-B*5701 (D)</p> Signup and view all the answers

Which gene variant is highly prevalent in Southeast Asia and predisposes patients to TEN after carbamazepine use?

<p>HLA-B*1502 (C)</p> Signup and view all the answers

Which gene variant is more prevalent in Northern European populations and associated with a broader range of carbamazepine-induced hypersensitivity reactions?

<p>HLA-A*3101 (D)</p> Signup and view all the answers

What type of reactions are thiopurines, such as azathioprine, used to treat?

<p>Autoimmune diseases like rheumatoid arthritis, inflammatory bowel disease, and organ transplant recipients (D)</p> Signup and view all the answers

Which enzyme influences the metabolism of thiopurines, such as azathioprine?

<p>Thiopurine S-methyltransferase (TPMT) (D)</p> Signup and view all the answers

Which gene variant is common in Asians and increases the risk of myelosuppression when treated with standard drug doses?

<p>TPMT*3A (A)</p> Signup and view all the answers

Which enzyme is responsible for the metabolism of clopidogrel, and has variants that affect its efficacy and risks?

<p>CYP2C19 (D)</p> Signup and view all the answers

What percentage of the variance in warfarin dose requirements is due to CYP2C9 variations?

<p>Approximately 10% (D)</p> Signup and view all the answers

Which gene has two variants (CYP2C92 and CYP2C93) that reduce enzyme activity and require lower warfarin dosages?

<p>CYP2C9 (D)</p> Signup and view all the answers

Which major histocompatibility complex (MHC) region on chromosome 6 in the human genome is associated with severe drug-induced hypersensitivity reactions and liver injuries?

<p>HLA-A gene (C)</p> Signup and view all the answers

Which allele increases the risk of bleeding when metabolizing clopidogrel?

<p>CYP2C19*17 (A)</p> Signup and view all the answers

Which antiviral medicine for HIV has a hypersensitivity reaction in around 5% of patients, which can be severe and fatal?

<p>Abacavir (D)</p> Signup and view all the answers

Which enzyme's loss-of-function variants (CYP2C19*2, *3, *5) make clopidogrel ineffective and have been associated with adverse clinical outcomes?

<p>CYP2C19 (A)</p> Signup and view all the answers

What percentage of the variance in warfarin dose requirements is due to VKORC1 variations?

<p>Approximately 25% (B)</p> Signup and view all the answers

What is responsible for causing severe systemic symptoms, liver damage (potentially fatal), and blistering skin rashes like Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN)?

<p>(MHC) region on chromosome 6 (C)</p> Signup and view all the answers

Which enzyme is responsible for the metabolism of Warfarin?

<p>CYP2C9 (D)</p> Signup and view all the answers

Which enzyme's gain-of-function allele increases the risk of bleeding?

<p>CYP2C9 (B)</p> Signup and view all the answers

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Study Notes

  • The NHS strategy considers factors like allele frequency, clinical benefit, drug usage, and body of evidence when deciding which gene-drug associations to incorporate into clinical practice.

  • Cytochrome P450 enzymes (CYPs), which impact drug metabolism, are coded by genes that vary in the population.

  • Differential metabolism by CYPs can lead to various metaboliser phenotypes, such as ultrarapid, intermediate, poor, and extensive metabolisers.

  • CYP2D6 is a liver enzyme that breaks down certain antidepressant, antiarrhythmic, and antipsychotic drugs.

  • Over 70 variant alleles of CYP2D6 have been described, with some causing increased and others decreased enzyme activity.

  • CYP2D6 is associated with several therapeutic areas, including antidepressants, antipsychotics, beta blockers, and antiarrhythmics.

  • Poor metabolizers require lower doses of some drugs, while ultrarapid metabolizers require higher doses to achieve the same effect.

  • Genetic variation in CYP2D6 affects codeine metabolism, with poor metabolizers failing to effectively convert codeine into morphine and ultrarapid metabolizers producing high levels of morphine.

  • Warfarin, a common anticoagulant, interacts with CYP2C9 and VKORC1, leading to the importance of correct dosing based on individual genetic makeup to prevent life-threatening side-effects.

  • Warfarin is commonly prescribed for people with blood clot conditions, such as DVT and PE, and those at risk of developing blood clots, like those with artificial heart valves.

  • Warfarin metabolism is influenced by variations in the CYP2C9 and VKORC1 genes.

  • European populations have two variants (CYP2C92 and CYP2C93) of the CYP2C9 gene, which reduce enzyme activity and require lower warfarin dosages.

  • Approximately 10% of the variance in warfarin dose requirements is due to CYP2C9 variations.

  • Approximately 25% of the variance in warfarin dose requirements is due to VKORC1 variations.

  • Genetic testing for these variants helps healthcare professionals prescribe safe and effective warfarin dosages.

  • Clopidogrel, an anti-clotting medication, requires metabolism by the CYP2C19 enzyme and has variants that affect its efficacy and risks.

  • Loss-of-function variants in CYP2C19 (CYP2C19*2, *3, *5) make the drug ineffective and have been associated with adverse clinical outcomes.

  • The gain-of-function allele CYP2C19*17 increases the risk of bleeding.

  • Severe drug-induced hypersensitivity and drug-induced liver injuries are a heterogeneous group of rare, potentially lethal reactions that can be caused by more than 200 unrelated compounds.

  • These reactions can result in mild skin rashes or severe systemic symptoms, liver damage (potentially fatal), and blistering skin rashes like Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN).

  • The strongest genetic associations with these reactions have been with HLA alleles, which reside in the polymorphic major histocompatibility complex (MHC) region on chromosome 6 in the human genome.

  • A rare variant of the HLA-A gene (HLA-A*33:01) causes excessive immune reactions to common medications that result in liver damage.

  • Abacavir, an antiviral medicine for HIV, has a hypersensitivity reaction in around 5% of patients, which can be severe and fatal.

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