Pharmocogenetics and complex disease Flashcards
Mendelian vs complex trait
A mendelian trait is controlled by a single gene and inheritance follows Mendels principles e.g. ABO blood grouping.
A complex trait is controlled by multiple genes + the environment e.g. eye colour, height and weight, personality
Give 6 examples of complex diseases
Diabetes, cardiovascular disease, cancer, asthma, hypertension
What sample do you study when looking at mendelian and complex diseases?
Mendelian - pedigree chart of one family
Complex - a large population
What is a single nucleotide polymorphism?
A single-nucleotide polymorphism (SNP, pronounced snip) is a DNA sequence variation occurring when a single nucleotide adenine (A), thymine (T), cytosine (C), or guanine (G]) in the genome (or other shared sequence) differs between members of a species or paired chromosomes in an individual.
They are the most common form of genetic variation in the human genome.
What are genome wide association studies?
In genetics, a genome-wide association study is an observational study of a genome-wide set of genetic variants in different individuals to see if any variant is associated with a trait.
It needs a very large sample size and expensive computing.
What is the risk allele?
The allele that confers a risk of developing the disease.
What is heritability?
A measure of how well differences in people’s genes account for differences in their traits.
How can heritability be studied?
Twin studies are used comparing monozygotic twins who share 100% of genetic material and dizygotic twins who share 50% of genetic material.
If we see a large variation in a trait between monozygotic twins then it is more likely that this trait is due to the environment than genetics.
What is missing heritability?
GWAs help identify many genetic loci. If a phenotype has a known heritability of 40%, the GWAs loci for that phenotype may be less than 5-10%. The difference is called missing heritability.
What are the 5 reasons suggested for missing heritabiltiy?
- Rarer SNPs
- Low frequency variants with intermediate effect.
- Interactions of genes not usually investigated
- Miscalculated estimate of heritability
- Accuracy and precision of diagnosis
Define pharmacogenetics
The study of variability in drug response due to genetic differences.
What is personalised medicine?
Personalised medicine is a medical model that separates people into different groups—with medical decisions, practices, interventions and products being tailored to the individual patient based on their predicted response or risk of disease using pharmacogenetics.
