1. A family history of a genetic condition
PEDIGREE CHARTS
A family history of a genetic condition
© 2016 Paul Billiet ODWS

2. What is a pedigree chart?
A record of the family of an individual
Used to study the transmission of a hereditary condition
Useful when there are large families and a there is a good family record over several generations.
© 2016 Paul Billiet ODWS

3. Studying human genetics
Pedigree charts offer an ethical way of studying human genetics
Dominant/Recessive
Relationships
Sex
Genotypes
Phenotypes
A genetic counsellor will still use pedigree charts to help determine the distribution of a disease in an affected family.
© 2016 Paul Billiet ODWS

4. Symbols used in pedigree charts
A marriage with five children, two daughters and three sons. The middle son is affected by the condition
Normal male
Affected male
Normal female
Affected female
Parents
Vertical line = Children
© 2016 Paul Billiet ODWS

5. Symbols Completely darkened= homozygous affected
Could be dominant or recessive

6. pedigree chart Generations are identified by Roman numerals. I II IIIIV
© 2016 Paul Billiet ODWS

7. Identifying
Dominant vs Recessive

8. Tongue rolling (R)
© 2016 Paul Billiet ODWS

9. Tongue rolling rr rr rr rr rr
© 2016 Paul Billiet ODWS

10. Tongue rolling rr Rr Rr Rr rr Rr Rr rr rr Rr rr
© 2016 Paul Billiet ODWS

11. Albinism 1. Dominant or récessive? (A)
© 2016 Paul Billiet ODWS

12. Albinism aa Aa Aa Aa Aa Aa Aa Aa aa aa aa aa
© 2016 Paul Billiet ODWS

13. 4 patterns to know Autosomal Dominant Autosomal Recessive Autosomal
Sex-linked (X) recessive
-There is no (y) transmission

14. Pattern #1- Autosomal Dominant
In general, males & females equally affected
NO skipping generations
Trait is expressed if allele is present

15. AD EX: Huntington’s disease
Build up of protein causes damage to nerve cells in brain
Most people develop symptoms in 40s-50s
Symptoms start w/movement problems, slurred speech, balance problems, swallowing difficulties
Huntington disease (right) showing a larger cavity where brain cells have died, compared with a normal brain (left).

16. Pattern #2 – Autosomal Recessive
In general, males & females equally affected
Can skip generations
Both parents are carriers
Trait is expressed only if homozygous

17. AR EX: Cystic Fibrosis
Defective chloride-ion transport protein in cell membranes
Symptoms – thick, heavy mucus clogs lungs, liver, pancreas
Most people do not survive past late 30s
Many treatments for symptoms, but NO cure

18. Pattern #3 - Autosomal In general, males & females equally affected
Father-son transmission of trait

19. Pattern #4 – Sex-linked recessive
In general, more males are affected than females
If mom is carrier  sons are affected, not daughters
If dad is affected  daughters are carriers
NO dad-son transmission
NO male carriers

20. EX: Red-Green Color Blindness
Affects males more than females
3 types of cone cells working together give you color vision (red, blue, green)

21. EX: Hemophilia Affects males more than females
Missing blood clotting proteins
Lots of bleeding from minor cuts
Can suffer internal bleeding from bumps/bruises
Can be treated w/injections of clotting proteins

22. Try this one
Autosomal dominant

23. Autosomal Recessive

24. Dominant Autosomal

25. Autosomal Recessive

26. Recessive X linked

27. Recessive Autosomal

28. Dominant Autosomal

29. Autosomal Recessive

30. X Linked Recessive