2: Pedigrees and risk

Question 1

Why are pedigrees used

Answer 1

provides clear summary
easy to identify patterns
identify potential carriers
calculate risk of passing disease/ being a carrier
allow informed choice

Question 2

Why are pedigrees used rather than testing for disease genes

Answer 2

many diseases have a mix of - sporadic, inherited, familial
causes of diseases can be unclear
impossible to test every family member

Question 3

limitations of pedigrees

Answer 3

incomplete information
incorrect information - people not related in reality
incorrect family history
important in clinical setting

Question 4

How to draw a pedigree diagram

Answer 4

Start at bottom with proband
Add siblings
Focus on one parent - ask about siblings/children/parents
add other side of family
ask about children of other partners

Question 5

Risk is

Answer 5

calculation of predicted chance of having the disease or being a carrier

Question 6

How to calculate risk from a pedigree

Answer 6

Work from person with known phenotype
if more than 1 affected individual - start with closest relative on either side
calculate risk
multiply risk

Question 7

What factors affect risk

Answer 7

Side of family disease is on : X-linked, mitochondrial
Ethnic background - sickle cell
Patient Info - phenotype, sex

Question 8

How to increase reliability of prediction

Answer 8

Get more data

Question 9

What are bayesian statistics

Answer 9

method for carrying out probability based on accuracy of pedigree