Part 4. Monogenic (qualitative) inheritance

This is the fourth part of a 5-part course Genetics for Breeders and Vets.

In the previous part of the course, we learned that a monogenic trait is typically caused by a mutation that causes a change in the function of a protein and thus affects the individual’s appearance. In this part, we will go through specific monogenic modes of inheritance and the associated pedigree charts.

We will go through :

• Predicting offspring traits (Punnett’s square)
• Inferring parental genotypes from offspring
• How alleles affect each other’s expression – dominance, incomplete dominance, over-dominance, codominance, epistasis
• Determining the mode of inheritance of a trait using a pedigree chart
• What are the safe combinations if the disease is inherited in an autosomal recessive or dominant manner? Or when the mutation is on the X chromosome?
• What is the probability of the disease being passed on to the offspring?
• Why doesn’t a genetically affected individual always become ill?