Flashcards in Pharmacogenomics Deck (12):
What is pharmacogenetics
the study of the relationship between individual gene variants and variable drug effects
What is pharmacogenomics?
describes the relationship between variants in a large collection of genes, up to the whole genome, and variable drug effects
Potential causes for variability in drug effects include factors such as...
- ethnic group
- liver and kidney function
- concomitant illnesses
- nutritional status
What are the two types of population dose curves?
unimodal and bimodal
What is the most common type of genetic variation?
change in a single nucleotide pair (termed Single Nucleotide Polymoprhism, SNP)
Why do some patients have a prolonged response to succinylcholine of hours instead of minutes?
presence of an atypical plasma cholinesterase (type of enzyme)
- due to SNP in gene for human plasma cholinesterase
- SNP changes acidic amino acid to a neutral amino acid; which reduces affinity of cholinesterase for choline esters
Some people are susceptible to the antimalarial drug primaquine, causing hemolytic anemia - what is this condition associated with?
amino acid substitutions in the G6PD enzyme that result from SNPs
Polymorphisms in Cytochrome P450 Genes
- polymorphism of the cytochrome P450 (CYP) enzymes for CYP2D6
- poor metabolizers and extensive meetabolizers
- CYP2D6 enzyme is responsible for the metabolism of drugs such as beta-blockers and tricyclic antidepressants, and for the metabolism of codeine to morphine
Polymorphisms in Thiopurine Methyltransferase
- azathioprine and mercaptopurine used in the treatment of various autoimmune, dermatologic, and hematologic disorders may cause fatal myelosuppression in persons deficient in thiopurine methyltransferase (TPMT)
Genetic Polymorphisms in Drug Targets
ex: polymorphisms of the B2AR results in differences in responsiveness of airways to the inhaled beta2-agonist (bronchodilator) albuterol
What are the major mechanisms through which genetic variation can alter responses to drug?
- increased/decreased drug absorption
- increased/decreased drug metabolism
- increased/decreased drug excretion
- increased/decreased drug efficacy through altered receptor-target affinity
- adverse drug reactions