Download Pedigree Notes - word

Pedigree Notes
A pedigree is a diagram of family relationships that uses symbols to represent people and lines to
represent genetic relationships. These diagrams make it a lot easier to visualize relationships
within families, particularly large extended families. Pedigrees are often used to determine the
pattern of inheritance (dominant, recessive, X-linked, etc.) of genetic diseases. A sample
pedigree is shown here:
In a pedigree squares represent males, and circles represent females. Horizontal lines connecting
a male and a female represent mating. Vertical lines extending downward from a couple
represent their children. Subsequent generations are, therefore, written underneath the parental
generation, and the oldest individuals are found at the top of the pedigree.
If the purpose of a pedigree is to analyze the pattern of inheritance of a particular trait, it is
customary to shade in the symbol of the individual that possess this trait. If the individual is a
carrier of the trait but does not express it, often their symbol with be partially shaded.
Patterns of inheritance include: autosomal dominant, autosomal recessive, X-linked, etc.
Here is a sample pedigree showing 3 generations:
What are the relationships between:
• Person 1 (generation 1) and Person 3 (generation 2) ________________________
• Person 5 (generation 2) and Person 6 (generation 2) ________________________
• Person 2 (generation 2) and Person 4 (generation 3) ________________________