Lecture 18: Genetic Disorders

Question 1

How are unaffected males and females represented in a pedigree diagram?

Answer 1

Male = unshaded square
Female = unshaded circle

Question 2

How are affected males and females represented in a pedigree diagram?

Answer 2

affected male = shaded square

affected female = shaded circle

Question 3

How are autosomal carriers shown in a pedigree diagram?

Answer 3

Half-shaded square or circle

Question 4

How are X-linked carriers shown in a pedigree diagram?

Answer 4

Dot in middle of circle

Question 5

How are deceased persons shown in a pedigree diagram?

Answer 5

Diagonal line through circle or square

Question 6

How are probands (person seeking medical attention) shown in a pedigree diagram?

Answer 6

Small arrow pointing to square or circle

Question 7

What does each line/level of a pedigree diagram show?

Answer 7

A new generation (denoted by roman numerals)

Question 8

Why do we use pedigree diagrams?

Answer 8

Provides a clear simple summary of information
able to spot patterns clearly
explain pattern to patient
calculate risk of passing on disease or being a carrier
allows informed choice