PEDIGREE ANALYSIS

PEDIGREE ANALYSIS

• Diagram that shows how traits are inherited from one generation to the next

• Diagram tracing a particular trait through a family

• Used by genetic counselors to predict the likelihood of passing on a genetic disease

• Ex: sickle cell anemia, downs syndrome, and cystic fibrosis

DRAWING A PEDIGREE • Generations are numbered

with Roman numerals (I, II, III) on the left side of the pedigree

• Print each persons name or number neatly under their symbol

• Children are put in age order from left to right if given, but may be rearranged to show special relationships (ex: marriages)

• Provide a key for all symbols used

Key to Pedigree Symbols

Male Square

Female Circle

Marriage Horizontal line between couple

Divorce Broken horizontal line between couple

Multiple marriages Numbered horizontal line between couples

Death Diagonal slash over person’s symbol

SiblingsVertical line from parents to a bracketed horizontal line over

siblings

Fraternal twins Connected by a triangular line above

Identical twins Connected by a triangular line above and a horizontal line between

Adoption Capital “A” inside symbol

Having a trait Shaded in as specified in your key

12

or

or

A Aor

or

SAMPLE PEDIGREE

SAMPLE PEDIGREE