1. Orderly diagram of a family’s genetic traits
Notes: Pedigrees
Orderly diagram of a family’s genetic traits

2. A pedigree shows…
relationships, sex, genotype & phenotype of each member
if an allele is dominant or recessive
if an allele is autosomal or sex-linked

3. Symbols Circle = female Square = male Horizontal line = parents
Vertical line = children
Symbol w/line through it = dead

4. More symbols
Half-Shaded = heterozygous not affected (recessive disorder)
Completely darkened = homozygous affected
Half-Darkened = heterozygous affected (dominant disorder)

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

6. 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).

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

8. 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

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

10. 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

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

12. 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

13. Try this one
Autosomal dominant

14. Autosomal recessive

15. Dominant - Autosomal

16. Recessive - Autosomal

17. Recessive, X-linked

18. Recessive - Autosomal

19. Dominant - Autosomal

20. Recessive, X-linked

21. Autosomal recessive

22. X-linked recessive