Genetics of Common Diseases

Question 1

If a trait is determined strictly by genes how do you expect the concordance values between MZ and DZ twins?

Answer 1

• 100% in MZ twins

- 50% in DZ twins (assuming they raise together)

Question 2

How do you expect the concordance if there isn’t a genetic contribution for a trait?

Answer 2

Equal concordance in MN and DZ twins

Question 3

Assuming the bias and the effect of genetic and environmental in some traits, what can you use to calculate the heritability? (A trait is not strictly genetic or environmental)

Answer 3

Calculate heritability from twin studies

Heritability=(CMZ-CDZ)/(1-CDZ)

Question 4

What is the effect of a mutation in a oncogene?

Answer 4

• one hit/gain function of a gene that promote cell cycle ▶️ tumor growth

Question 5

What is the effect of a mutation in a tumor suppressor gene?

Answer 5

• tow hits/loss protein or reduce activity, both copy, don’t inhibit the cell cycle ▶️ tumor growth

Question 6

Which is the result in a p53 gene mutation?

Answer 6

• Li-Fraumeni syndrome: almost always heterozygous, higher prevalence of the affected and their families than that of the general population for certain cancers.

Question 7

What is needed to lead to cancer in case of a p53 gene mutation?

Answer 7

A loss of function somatic mutation in a cell (second hit)

Question 8

How do you assess the recurrence risk for a multifactorial disease? Examples

Answer 8

• empirical recurrence risk
• based en direct observation data
• cleft lip and/ or palate, DM type 2, HTA, Obesity, CVD, cancer, etc