Pedigrees

Pedigrees Pedigrees show how a trait/disorder is passed from one generation to the next

Symbols:o Squares = males (XY), circles = females (XX)o Horizontal lines connect breeding coupleso Vertical lines connect parents to childreno Shading (filled in) = individual has the traito No shading = individual does not have the traito Half shading or a dot = a carriero A diagonal line means deatho Roman numerals show generationso 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 or Sex-linked? ____________________Is this dominant or recessive? ____________________Assign genotypes to the pedigree to show the inheritance pattern

aa

Aa

Aa

aa Aa Aa

Aa

Aa or AA

Aa

Aa

aa aa

aaaa

DominantAutosomal

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!

Sex-linkedRecessive

XBY XBXb

XbY XBXb XBY

XBY

XBY

XbY

XbY XbY

XbY

XbY

XBXbXBXb

XBXb

XBXb

Pedigree with half-shading to show carriers