Pedigrees

Pedigrees Pedigrees show how a trait/disorder is passed from one generation to the next Symbols: Squares = males (XY), circles = females (XX) Horizontal lines connect breeding couples Vertical lines connect parents to children Shading (filled in) = individual has the trait No shading = individual does not have the trait Half shading or a dot = a carrier A diagonal line means death Roman numerals show generations Numbers assign an individual to a generation

Interpreting Pedigrees Trait is dominant or recessive? Skips a generation = recessive Every generation = dominant Trait is autosomal or sex linked? Affects ♂ and ♀ equally → autosomal Affects ♂ more than ♀ → sex-linked Females tend to “carry” a trait and affect their sons Females get the trait from affected father and carrier/affected mother Affected males got it from their mother and give it to their daughters to “carry.”

Autosomal Dominant aa Aa aa Aa aa Aa aa Aa or AA Aa aa aa Aa Aa Autosomal or Sex-linked? ____________________ Is this dominant or recessive? ____________________ Assign genotypes to the pedigree to show the inheritance pattern Dominant

Sex-linked Recessive XBY XBXb XbY XBXb XBY XBXb XBXb XbY XBY XbY XBXb Autosomal or Sex-linked? ____________________ Is this dominant or recessive? ____________________ Assign genotypes to the pedigree to show the inheritance pattern Fill in what you know first! Recessive

Pedigree with half-shading to show carriers