genetics of common disease

Question 1

twin studies

Answer 1

monozygotic twins = share 100% of germ line genetic variation

dizygotic twins = share 50% of germ line genetic variation

Question 2

estimating heritability

Answer 2

heritability is the proportion of variation in a trait explained by inherit genetic variants

Question 3

measuring correlation

Answer 3

correlation is measured between -1 and 1 where:
- 1 = strong positive relationship
-1 = strong negative relationships
0 = no relationship at all

Question 4

Genome wide association studies

Answer 4

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

Question 5

define linkage disequilibrium

Answer 5

diff between the observed frequency of a particular combination of alleles at two loci and the frequency expected for random association

Question 6

strong LD = fewer SNPs need genotyping

Answer 6

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

Question 7

genome wide association study

Answer 7

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