genetics of common disease Flashcards
twin studies
monozygotic twins = share 100% of germ line genetic variation
dizygotic twins = share 50% of germ line genetic variation
estimating heritability
heritability is the proportion of variation in a trait explained by inherit genetic variants
measuring correlation
correlation is measured between -1 and 1 where:
- 1 = strong positive relationship
-1 = strong negative relationships
0 = no relationship at all
Genome wide association studies
a genome wide association study is used to associate specific genetic variations with particular phenotypes
method involves scanning genomes many diff people and looking genetic markers that can be used to predict the presence of a disease/trait
define linkage disequilibrium
diff between the observed frequency of a particular combination of alleles at two loci and the frequency expected for random association
strong LD = fewer SNPs need genotyping
LD = between two SNPs decreases with physical distance as more likely to have recombination event between them.
extent of LD varies greatly depending on region of genome
genome wide association study
variants associated with disease will be found at a higher frequency in cases than in controls
statistical analysis is carried out to indicate how likely a variant is to be associated with a trait