1. Human Pedigrees
Drawing and Analysis

2. Genetic Counseling Helping individuals and prospective parents
Your learning gives you the opportunity to determine some probabilities and patterns of inheritance yourself!

3. Pedigrees
A pedigree is a biological family tree that shows the interrelationships between parents and children across generations.
Helps illustrate a pattern of inheritance for a single trait through that family
Pic of Queen’s Vic. family

4. Standard Symbols in Pedigrees
Male
Female
Unspecified Gender

5. Standard Symbols in Pedigrees
Clinically Unaffected
Clinically Affected
Carrier
Not Clinically Affected
Some pedigrees show phenotype only (no half-shaded boxes; some show genotype (carriers are half-shaded) You will need to determine which system is used in each problem.

6. Conventions in Drawing Pedigrees
Parents
Regardless of Social Relationship
Male partner on left (usually)

7. Conventions in Drawing Pedigrees1 2 II 1 2 3
Full Siblings
(in order of age from left to right)

8. Conventions in Drawing Pedigrees1 2 II 1 2 3 4
Monozygotic Twins
Dizygotic Twins

9. Conventions in Drawing Pedigrees1 2 3
Separated
Consanguinity II
Convention to draw male on lefy but also older relationships/siblings?? Brackets
Adopted 1 2 3

10. Conventions summary

11. Patterns of Inheritance
Dominant:
Trait is expressed in every generation – eg. Huntington’s, brown eyes
Not seen in offspring unless present in a parent
Recessive:
Trait may skip generations – eg. TaySachs
Sex-Linked:
Y linked – only males are clinically affected
X linked – affected males more common, may have normal parents, affected females must have affected father

22. autosomal dominant

25. Pedigree Practice Autosomal dominant Autosomal recessive
X-linked recessive

26. Pedigree Practice (more rare)
D) X-linked dominant
E) Y-linked

27. Pedigree Practice
Cardiomyopathy (hypertrophy)
Autosomal dominant

28. Pedigree Practice
Warped ear
Autosomal recessive

29. Pedigree Practice
Neurofibromatosis
Autosomal dominant

30. Pedigree practice
Hemophilia
X-linked recessive