10-Understanding Genetic Diseases

Question 1

What are DNA markers?

Answer 1

Regions of DNA that vary between indviduals

Question 2

How are DNA markers used to find the cause of genetic diseases?

Answer 2

Chromosomal location is known

Allows you to see if the disease gene is close to or ‘linked’ to the DNA marker

Question 3

What is meant by genetic heterogeneity?

Answer 3

Presence of a variety of genetic defects which cause the same disease

Question 4

What is pleiotropy?

Answer 4

Contrast to genetic heterogeneity in which a single gene may cause multiple phenotypic expressions or disorders

Question 5

How is Retinitis Pigmentosa linked to extensive genetic heterogeneity?

Answer 5

First gene identified was Rhodopsin

70 different loci and genes for RP

Question 6

Why use molecular diagnosis?

Answer 6

Improve clinical diagnosis
Provide prognostic information
Genetic counselling
Eligibility for gene-specific treatments

Question 7

How do genetic factors affect the risk of clot formation?

Answer 7

Factor V leiden mutation is a single base change causing the altercation of the site at which clotting factor V is cleaved by protein C
Resultant factor V is reisitant to degradation and increases the amount and duration of thrombus formation