1. 5.3- Following Patterns of Inheritance in Humans
SBI3U

2. What is a Pedigree? Flowchart; “Genetic Family Tree
Symbols show inheritance patterns of traits over generations
Used to determine presence/absence of an allele responsible for disease in an individual.

3. Pedigree Symbols

4. Roman numerals symbolize generations
EXAMPLE:
*NOTE:
Roman numerals symbolize generations
Birth order, within each group of offspring, is drawn left to right (first born to last born)

5. Autosomal Inheritance
Inheritance of traits on chromosomes 1 -22(autosomes)
Autosomal dominant:
Disease causing allele is dominant
Individual has one or both copies of the allele
Autosomal recessive:
Disease causing allele is recessive
Individual has both copies of allele

6. Autosomal Dominant Inheritance
Each affected individual has an affected parent; no skipping of generations.
Males and females are equally affected.
About 1/2 of the offspring of an affected individual are affected (the recurrence risk is 1/2).
Normal siblings (ex. II-3) of affected individuals have all normal offspring.

7. Example- Pedigree: Autosomal Dominant Inheritance
Question: Why must individual II-1 be heterozygous?

8. Autosomal Recessive Inheritance
Two unaffected parents can have an affected child
This only happens if both the parents are “carriers”
Both are heterozygous (so they do not express it)

9. Example –Pedigree: Autosomal Recessive Inheritance
Question: Are parents II 3 and 4 heterozygous or homozygous? Explain.

10. Examples of Human Diseases – Autosomal Inheritance
2)Huntington Disease
1)Sickle Cell Anemia
Dominant
Loss of muscle control and mental ability
Recessive
Irregularly shaped red blood cells
3) Cystic Fibrosis
Recessive
Mucus build up in lungs = trouble breathing

11. Let’s try this…Who can roll their tongue???

12. Genetic Tests

13. Genetic Counselling Genetic counsellors are trained in human genetics
Work with families/individuals who may be at risk for a genetic disorder.
Look at probability of passing on a disease-causing allele to children through family history using Pedigrees

14. What issues might be associated with genetic testing?
Class Discussion:
What issues might be associated with genetic testing?

15. Gene Therapy
Technique used by introducing the correct form of a gene into a patient’s genome
Goal? For curing genetic disorders!!
METHOD-Normal gene is copied and inserted into vector (viruses are used bc they can easily infect human cells.

17. The Future of Gene Therapy…
Still in the experimental stage
2 Problems/ Obstacles:
1)Problems with type of vector
2)Poor integration of gene into chromosomes
In 2000, first human gene therapy treatment was performed for heart disease at St. Mike’s Hospital, Toronto

18. Homework Read and review 5.3-pg 219-226 Chapter 5 QUIZ T.B.A
Complete pg. 227 # 2, 7, 8
Pedigree Assignment