Genetic Basis of Multifactorial Disease

Question 1

Liability (Genetics)

Answer 1

All the factors which influence the development of a multifactorial trait/disorder

Question 2

Liability-Threshold Model

Answer 2

All of the liabilities of all individuals form a continuous variable, and individuals on the right side of the line represent those with the abnormal phenotype (disorder)

Question 3

How do you measure susceptibility for Cleft Palate?

Answer 3

Follows Gaussian Distribution; if it exceeds

Question 4

Heritability

Answer 4

The proportion of the total variance in a population that is genetic. The overall phenotype is the sum of genetic and environmental variance

Question 5

Polymorphism

Answer 5

Genetic change that doesn’t cause disease; any variation in the human genome that has a population frequency of more than 1% and may predispose to common diseases

Question 6

Synonymous Polymorphism

Answer 6

A change in DNA sequence, but not in the actual amino acid produced

Question 7

Nonsynonymous Missense Polymorphism

Answer 7

A mutation that changes both the DNA sequence and the amino acid

Question 8

Nonsynonymous Nonsense Polymorphism

Answer 8

Changes the DNA sequence to code a premature stop codon

Question 9

What are some weaknesses of family studies?

Answer 9

does not take into account a risk caused by a shared environmental risk factor

Question 10

What are some problems with association studies?

Answer 10

How do you decide which gene to look at?
How do you know which polymorphism to look at?
significant association may be true
significant association may be due to chance
significant association may be false due to population stratification (control group must match affected group)
analyse as many polymorphisms as you can across the genome in a disease population and a control group