L4 Study Designs Flashcards
What are the 2 purposes of studies
See if it is inheritable/a genetic component eg via twins
See what the association is
Do alleles have to be single bases or snps
No can be sequences of eg cnvs or inversions
How do children of same parents differs so much
Homologous recombination some have different alleles from diff parents
Why is the phenotype and genotype in complex called a probabilistic relationship
Not 100% penetrance
Does having both copies of a risk allele cause you to have disease in complex
No
What is the probability represented as (2 ways)
Odds ratio and genotype relative risk
How to calculate genotype rr
Baseline risk of disease x number of the risk alleles (0-2)
Where are mutations/snps often in complex disease located
Non coding regions therefore affecting gene exp levels more then function
How do you recognise recessive pattern in a pedigree
1 generation usually affected and seen in consanguineous families ie inbreeding
What are family studies used for
Detect a genetic contribution to a disease
What doesn’t family studies do so what do you have to do after
Doesn’t find causal variant so need to do functional tests on model organisms eg via crispr ko or on cell thpes
Do family studies work better for Mendelian disease
Yea
What type of analysis is done on family studies
Segregation analysis
What does this do
Estimates things like gene freq, shared environmental effects, penetrances in the family which best explain the inheritance pattern
Does segregation analysis allow to study polygenic inheritance
Yes to an extent
How is twin studies good for complex to see if there is a genetic determinant
Studies concordance rates between mz and dz since shared environments. If higher concordance in the mz means it is likely genetic factors
What does recurrent risk do
Another way to assess genetic contribution to a disease
What does rr mean
Probability of the disease recurring in family
What does proband mean
The person who first had the disease in the family
Which 3 people related to proband can a recurrence risk be calculated for
Sibling Ks
Offspring Ko
Mz twin Kmz
What is the recurrence ratio
Ks/k (whole popn risk)
If ks is 3 what does this mean
3 fold more likely than rest of popn
Whcih study is done mainly for Mendelian diseases to localise the genetic contributions
Parametric linkage analysis
What does this entail
Using large pedigrees and obtaining dna from then to genotype specific genetic marker loci
