pedigree analysis diagram that shows how traits are inherited from one generation to the next...
Post on 30-Dec-2015
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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
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