1. Orderly diagram of a family’s genetic traits
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. Note: not all pedigrees will half shade a heterozygous carrier

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

7. 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).

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

9. 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

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

11. 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

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

13. 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

14. Try this one
Autosomal dominant

15. Autosomal recessive

16. Dominant - Autosomal

17. Recessive - Autosomal

18. Recessive, X-linked

19. Recessive - Autosomal

20. Dominant - Autosomal

21. Recessive, X-linked

22. Autosomal recessive

23. X-linked recessive