Lec 1 Flashcards
What’s the deffinition if pharmacogenetics
The study of genetic variation in humans that gives rise to different responses to drugs
What is the deffinition of pharmacogenomics
The application of genomic technologies for the optimisation of drug therapies soda pets to an individuals genetic make up
Both terms apply to the study of how an individual genetic make up affects the bodies response to a drug
What is discrimination
Recognition and understanding of the difference between one thing and another
Genetically different people may have different outcomes to the same actions
The same patient under a different environment may have a different outcome
DNA facts
23 Pairs of chromosomes (number 1 is the biggest)
DNA tightly wrapped around proteins for efficient packing
3 billion base pairs
20,000 -25,000 genes
We are all 99.9% genetically identical
23rd pair are the sex chromosomes, X+Y
What are the main classes of genetic diseases
Dominant: Huntington’s disease
Recessive: cystic fibrosis
X linked disease: haemophillia
Chromosomal diseases: Down’s syndrome has an extra copy of chromosome 21
Susceptibility to many diseases has a genetic component but is less obvious from patterns of inheritance
Multiple genes may interact with the environment to play apart
State some genes which can cause disease
app-E4 (variant of alipoprotein E gene) linked to late onset Alzheimer’s disease
Factor V Leiden- mutation in coagulation factor V, increased risk of VTE
Human genome project (HGP)
The human genome project commended in 1990
1st sequence completed in 2003
Aim of the project is to characterise genes and establish their function in health and disease
What is the international HapMap project
Haplotype Map project is creating a database of common human genetic polymorphisms
Taken from a range of individuals from different populations
Facilities discovery of genetic variation involved in more common diseases and responses to drugs
What is the goal of pharmacogenomics
Individuals respond differently to drugs
The genetic differences contribute to the variation in drug responses observed amongst individuals (environment, age, diet, lifestyle and health effect response)
Drugs may one day be tailor- made to an individuals genetic make up
What are SNPs
Single nucleotide polymorphism (SNP) are substitutional is an individual base along a chromosome
SNPs occur on average somewhere between every 1/100 - 1/1000 base pairs m
Over 1.4 mil SNPs were identified in the HGP, 60,000 of which were in coding regions
SNPs are most likely to make a difference if they are in a coding region or gene regulating region such as promoter or transcription factor binding site
What can SNPs effect
Drug metabolism enzymes
Drug transporters which regulated the absorption distributing and excretion of drugs
Drug targets
Disease or treatment modifying genes (such as genetic variation in risk of side effects)
State some drug metabolising enzymes
CYP2C9- anticoagulation effects of warfarin
CYP2C19- peptic ulcers response to omeprazole
CYP2D6- antidepressant toxicity, codine analgesia
Dihydropyrimidine dehydrogenase- neurotoxicity to flurouracil
State some drug targets
ACE- BP reduction, lipid changes
B2- adrenergic receptor- bronchodilators
Dopamine receptor- antipsychotic response
Serotonin transporter- antidepressant
State some genetic polymorphism that effect drug effects
Disease or treatment modifying agents:
APOE- response to statin in atherosclorosis progression, also Alzheimer’s disease
HLA- increase risk of hypersensitivity in response to abacavir
Prothrombin and factor V- risk of deep vein thrombosis in response to oral contraceptives
What is TPMT
Thiopurine-S-Methyl Transferase
A monogenic trait that effects drug metabolism
It is the most important inactivation pathway for mercaptopurine and azathiopurine in haematopoietic tissue
These drugs are used as immunosuppressants and treatment of neoplasia
TPMT facts and figures
TMPT is highly variable
90% of people= high activity
10% of people= intermediate activity
0.3% of people= Low or no activity
TMPT deficiency can lead to haematological toxicity in normal doses
How do we identify relevant SNPs
PCR qPCR FISH(fluorescent in soft hybridisation) Immunohistochemistry Array comparative hybridisation PCR followed by sequencing
Describe immunohistochemistry
Design an antibody that will have a receptor site complementary to the protein of interest
We are limited to proteins on the outside of the cells because to look inside we have to kill them
1) produce a primary antibody which will bind to the target protein 2) then add a secondary antibody which will bind to the primary 3) we then place a tag onto the secondary antibody so when it binds it lights up
Describe FISH
FLORESCENT IN SITU HYBRIDSATION
used more for identifying areas on chromosomes
Instead of placing a probe onto a protein it is placed on a DNA, with a florescent marker
This allows us to recognise how much of a gene is present in a chromosome or if there is any at all and the implication of that
Describe PCR
polymerase chain reaction
2 strands of DNA double helix physically seperated
2 DNA strands become templates for DNA polymerase to selectively amplify target DNA
1) denature stage 94-95’C
2) annealing stage 50-56’C (primer is added)
3) extending stage 72’C
This multiplies exponentially the amount of DNA
Describe qPCR
Quantative PCR
Real time PCR
Amplifies and simaltaneously quantifies target DNA molecules
Target DNA strands is hybridised with probe
Measure the amplification of the DNA
We basically no how much
Describe micro-array
DNA strands are immobalised on a probe
Go through PCR and apply to micro-array
Genes of interest will stick
Add florescent probe and scan
+ve: we can apply it to the entire genome
-ve: computing power to process this is huge and time taken to process this
Ethnic drugs the case of BiDil
Some drugs only work in people from certain ethnic backgrounds
BiDil is a fixed dose combination of isosorbide dinitrate and salazine
Treatment of congestive HF
Originally reflected by the FDA in 1997, when trials of Caucasian showed no effect
Approved in 2005 for African Americans only
Mortality reduced by 43%
African Americans respond less well to ACEI
