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

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

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

8. Rule #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

9. Try this one
Autosomal dominant

10. Dominant - Autosomal

11. Recessive - Autosomal

12. Recessive, X-linked

13. Autosomal recessive

14. Recessive - Autosomal

15. Dominant - Autosomal

16. Recessive, X-linked

17. Autosomal recessive

18. X-linked recessive