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Pedigree
“genetic” family
tree
Page 3
Pedigree Symbols
Male
Page 4
Pedigree Symbols
Female
Page 5
Pedigree Symbols
Mating between individuals
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Pedigree Symbols
Mating between close relatives
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Pedigree Symbols
Offspring “line”
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Pedigree Symbols
Label generations(Roman Numerals)
I
II
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Pedigree Symbols
Label birth order(oldest youngest)
I
II
1
1
2
2 3
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Pedigree Symbols
Identical Twins
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Pedigree Symbols
Nonidentical (Fraternal) Twins
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Pedigree Symbols
Offspring of unknown sex
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Pedigree Symbols
Aborted or stillborn
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Pedigree Symbols
Deceased
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Pedigree Symbols
Affected individual
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Pedigree Symbols
Heterozygousindividual
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Pedigree Symbols
X-linked carrier (remember: only woman can be X-linked carriers)
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Drawing a pedigree
Draw a pedigree that shows three children (one older brother and two younger sisters). The mother is older than the father. The mother’s father is older but the father’s mother is older. The eldest daughter, the father’s father (grandfather), and the mother are afflicted with a recessive disorder.
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Drawing a pedigree
I
II
III
1
1
1
2
2
2
3
3
4
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Interpreting Pedigrees
Autosomal•“Equal” number
of afflictedmen and women
Sex-linked•One sex is
afflicted morethan the other
Dominant•Does not skipa generation•No carriers
Recessive• Can Skip Generations
•Women and mencarriers
Dominant•No carriers
•More femalesafflicted than
males
Recessive•Only women
Carriers•More males afflicted
than females•Afflicted women must have afflicted
fathers
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Afflicted Males
More afflicted men than women
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Afflicted Males
AfflictedFemales
“Equal” Afflicted Men and Women
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Autosomal Dominant
Parent with Trait
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Autosomal Recessive
Parent can exhibit trait
SkipsGeneration
Page 25
AutosomalAA Aa aa
Dominant
Recessive
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Sex-linked
X-linked Dominant
X-linked Recessive
XAXA
XAXA
XAXa
XAXa
XaXa
XaXa
XaY
XaY
XAY
XAY
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Sex-linked Recessive
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Autosomal Dominant
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Autosomal Dominant
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Sex-linked Recessive
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Describe this family
Autosomal Recessive
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Label the genotypesAutosomal recessive
aa
aa
aaaa
aa
Aa
Aa
AaAa
Aa
? ?
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Describe this family
Sex-linked Dominant
Page 34
Label the genotypesSex-linked Dominant
XAY XaXa XAXa
XaY XAXa?XAY
?
XAXa XAXaXAXa
XaY XaY XaY