Flashcards in Unit 7 - Personalized Medicine and Pharmacogenomics Deck (22):
pharmacogenetics VS pharmacogenomics VS pharmacokinetics
genetics: heritable variation to inter-individual variation in drug response
genomics: field of new drug development based on rapidly increasing knowledge of all genes in human genome
kinetics: study of mechanisms of absorption and distribution of an administered drug
why don't some drugs work in some patients?
the normal "wild type" allele has normally functioning enzymes that respond to medications appropriately
-mutations in any one part of the pathway will cause changes and different outcomes, so mutant protein is unable to interact with drug properly, causing either no effect or ill effect
what is drug design influenced by?
what are the ADME core markers? the most well known?
genes involved in drug metabolism; most well known are CYP450
what are the different classes of function of CYP2D6 and their number of functional alleles?
1. poor - 0 functional alleles (very low level of enzyme activity, so slow conversion process, and may be ineffective)
-drug accumulation may be toxic, so need lower doses
2. intermediate - 1 allele (heterozygote with 1 mutant, 1 normal; can use drug at a slower rate, so need lower doses to avoid toxicity)
3. extensive - 2 alleles (normal; work in expected fashion, and group that must drugs target)
4. ultra - more than 2 alleles (duplicate copies, and degrade drug so rapidly that it's eliminated before effect takes place; need higher doses or other drugs)
are there ethnic differences in frequencies of classes of drug response?
what is the mechanism of warfarin?
inhibits epoxide reductase (Vitamin K reductase)
-prevents oxidized K from becoming reduced K, which activates the clotting cascade
-so warfarin will prevent clotting, as constant reduced K is needed for clotting
what are downsides to using warfarin?
1. reacts with many common medicines like antibiotics, aspirin, ibuprofen, and acetaminophen (increased risk of bleeding)
2. eating lots of vit K will reduce effectiveness, but other foods (ginger, garlic, etc.) will increase risk of bleeding
3. excessive alcohol use changes effects
how is the proper amount of warfarin found in patients?
trial and error; initially give normally benign dose and see if it's effective (keep), ineffective (increase dose), or negative effect (decrease dose and give vit K)
what are 2 genes that directly affect warfarin metabolism?
1. VKORC1 allele of VKOR gene - 30% of variation
-low dose (more sensitive - Asians) VS high dose (more resistant so need higher dosage - Blacks)
2. CYP2C9 allele of Cyt P450 - 10% of variation
-polymorphisms most common in Caucasian, and rare in Blacks and Asians
what are the different warfarin doses for the VKORC1 1173 genotype if:
CC (37%) - 6.2 mg/dL
CT (47%) - 4.8 mg/dL
TT (16%) - 3.5 mg/dL
what is one specialty where personalized medicine is constantly used?
-patients are evaluated individually, with specific types of tests ordered that directly address patient's personal situation
-all data are collected and combined to provide unique characterization
how is microarray technology used? what can it detect?
genome-wide scan of a person's genetic complement
-gene chip may be developed to include subset of important human genes, including mutations
--need to decide what genes on chip
-can detect uniparental disomy, regions of homozygosity
what is expected in offspring of cosanguine patients?
expected ROH 6.25% (+/- 2.43) with several hundred genes
what are the different identity by descents?
3. inbred populations - geographically isolated
4. ethnic populations
what is needed info for next generation sequencing?
1. mutations specific to one+ cancer categories
2. currently known set of genes associated with Xmal microdeletions
3. genes commonly associated with birth defects
4. ADME core markers for drug metabolism
what does the Genetic Information Nondiscrimination Act (GINA) do? not do?
-prohibits insurers or health plan administrators from using genetic info in decisions about coverage or rates
-prohibits employers from using genetic info for hiring, firing, or promoting decisions
-cover life, disability, or long-term care insurance
-apply to businesses with <15 employees
-prohibit a health insurer from determining eligibility or premium rates based on disease presence
what are the three different categories of screening?
1. prenatal screening
2. newborn screening (affecteds)
3. carrier screening (phenotypically normal, but at risk for affected child)
disease: clearly defined and treatable, with reasonably high population incidence
test: large scale, rapid, and inexpensive, with low false positives and no false negatives
f/u: if definitive diagnosis, can provide prompt treatment, and there is genetic counseling available
what are key factors in carrier screening?
1. mutation must be in a reasonably high frequency in population
2. test is suitable for mass screening
3. genetic counseling is available to explain results to family
4. prenatal testing is available so that when carrier couples are identified, it's possible to see if pregnancy will result in affected child
what are the 5 main disorders that are high frequency in Ashkenazi Jews?