Pedigrees Biology 30 Genetics Mrs. S. Pipke-Painchaud

Pedigrees A pedigree (family tree) allows you to study the pattern of inheritance with regard to a specific phenotype –Dogs, horses, and a number of other animals have pedigrees or family trees. Definition: diagram showing ancestral relationships and transmission of genetic traits over several generations in a family.

Sample Pedigree

Diagramming Rules - Female - Male - Unknown sex A shaded in shape means that he or she has the trait in question.

Recessive Trait Example Use the letter A

Autosomal Dominant Pedigree “Each of the four hallmarks of autosomal dominant inheritance are fulfilled. Each affected individual has an affected parent; there is no skipping of generations. Males and females are equally likely to be affected. About 1/2 of the offspring of an affected individual are affected (the recurrence risk is 1/2). Normal siblings (II-3) of affected individuals have all normal offspring.” (Image and quotation from:

Myopia Is this a dominant or recessive trait? Why? - Assign letters.

X-Linked Pedigree Example

Resources Genetics and Rare Conditions Website: – BioLessons: – cs/sol_questions/default.asphttp:// cs/sol_questions/default.asp