Genetics Of Common Disease

Question 1

What is the definition of heritability?

Answer 1

The proportion of variation in a trait explained by inherited genetic variants

Question 2

How is heritability measured?

Answer 2

By the trait similarity in monozygotic twins vs the trait similarity in dizygotic twins

Question 3

How much of the germline genetic variations do monozygotic twins share?

Answer 3

100%

Question 4

How much of the germline genetic variations do dizygotic twins share?

Answer 4

50%

Question 5

How much of the genetic variations do full siblings share?

Answer 5

50%

Question 6

How much of the genetic variations do half siblings share?

Answer 6

25%

Question 7

What will the h^2 of a gene be if it’s highly influenced by genes?

Answer 7

> 0.8

Question 8

What is linkage disequilibrium?

Answer 8

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

Question 9

What does a strong linkage disequilibrium mean for the SNPs?

Answer 9

Less need genotyping as LD between two SNPs decrease with physical distance

Question 10

What is the Bonferroni correction?

Answer 10

If the number of SNPs genotyped is n, we set the threshold to be 0.05/n so that we can avoid including false positives in our findings

Question 11

What is the goal of GWAS?

Answer 11

Identify genetic regions that explain differences in phenotype among individuals in a study population

Question 12

What are the three possibilities if you identify a SNP that is significantly associated with disease?

Answer 12

There is a causal relationship between the SNP and disease
The marker is in linkage disequilibrium with a causal locus
False positive