1. How can human traits be traced through generations?
Pedigree
How can human traits be traced through generations?

2. Pedigree Chart which shows the relationships within a family
Deals with the inheritance of a single gene
Pedigrees show how a trait is transmitted through three generations of a family

3. Pedigree
In a sex linked pedigree men will have the disease and women will mostly be carriers of the disease.

5. Pedigree
Male Female

6. Pedigree
Male Carrier Female Carrier

7. Pedigree
Male with expressed trait
Female with expressed trait

8. Pedigree
A horizontal line connecting male and female represents marriage

9. Pedigree
Vertical line and a bracket connect the parents to their children

10. Types of Inheritance Autosomal Recessive Inheritance
Autosomal Dominant Inheritance
Sex-Linked Recessive Inheritance

11. Autosomal Recessive Inheritance
Expression of disease only in homozygous recessive state (skips generations
Carriers usually have no symptoms
Both males and females are affected
Certain disorders can occur more frequently in different ethnic backgrounds
Examples: Albinism, Cystic Fibrosis & PKU

13. Autosomal Recessive Pedigree

14. Albinism

16. Autosomal Dominant Inheritance
Dominant gene mutation
Expression of disease in heterozygous state
Seen in all generations (no skipping)
Variable expressivity
Example: Neurofibromatosis & Huntington’s

18. Autosomal Dominant Pedigree

19. Neurofibromatosis

20. males affected, females usually unaffected carriers
X-Linked Recessive Inheritnce
males affected, females usually unaffected carriers
affected males do not have affected children
Example: Color blindness

21. Color blindness