Inheritance - Pedigrees A pedigree is a graphical representation of the generations of a family Can be used to trace genetic disorders or a person who is a carrier for a disorder Tool used by genetic counselors and doctors

Inheritance - Pedigree Set-up: Males represented by squares Females represented by circles Darkened circle/square represents a person with the disorder Half darkened represents a carrier for a disorder Blank/white represents a person without the disorder Mating is shown with a horizontal line connecting a circle and square Offspring are shown with vertical lines connecting to the parents

Inheritance - Pedigree Modes of Inheritance: Autosomal Dominant: affected individual has an affected parent; cannot skip generations. Autosomal Recessive: affected individual may not have an affected parent; can skip generations. Both parents could be heterozygous X-link Recessive: affected individual may not have an affected parent. Males are more likely to be affected than females. Females may not have the disease but can pass it on (carrier) Affected males must have an affected or carrier mother

Inheritance - Pedigree Examples: 1. 2. Which mode of inheritance does this pedigree likely show? Autosomal dominant What are the genotypes of individuals 1 – 5? Use letter “a”. 1 = aa 2 = Aa 3 = aa 4 = Aa 5 = aa Which mode of inheritance does this pedigree likely show? What is the likely genotype for individual 4? c) What is the likely genotype for individual 5?