Extensions of Mendelian Analysis

1. Extensions of Mendelian Analysis • Modifications of Mendelian Ratios • Single Gene modifications • Two gene pair modifications: modified 9:3:3:1 ratios • Modification of Expression

2. Single Gene modifications • Incomplete dominance (partial dominance) • Multiple alleles • Lethal alleles

3. Incomplete dominance (partial dominance) • Expression of a heterozygous phenotype that is distinct from and usually intermediate to either homozygous phenotype

4. Incomplete dominance (partial dominance) Tay Sachs and Sickle Cell Anemia Heterozygous are intermediate at the biochemical level.

5. Multiple Alleles &Co-Dominance

6. Bombay phenotype • H allele affected • Recessive epistasis • Show O phenotype • Genotype variable

7. Lethal alleles • Yellow dominant to Agouti coat color • No purebred yellow • Deletion mutation • Recessive for lethality

8. Two gene pair modifications: modified 9:3:3:1 ratios • Epistasis • Suppression • Complementary gene action

9. Recessive Epistasis

10. Dominant Epistasis

11. Suppression

12. Complementary gene action

13. Complementary gene action

14. Modification of Expression • Pleiotropic effects • Penetrance and Expressivity

15. Pleiotropic effects

16. Penetrance No expression

17. Expressivity