Pedigree

Pedigree

“genetic” family

tree

Pedigree Symbols

Male

Pedigree Symbols

Female

Pedigree Symbols

Mating between individuals

Pedigree Symbols

Mating between close relatives

Pedigree Symbols

Offspring “line”

Pedigree Symbols

Label generations(Roman Numerals)

I

II

Pedigree Symbols

Label birth order(oldest youngest)

I

II

1

1

2

2 3

Pedigree Symbols

Identical Twins

Pedigree Symbols

Nonidentical (Fraternal) Twins

Pedigree Symbols

Offspring of unknown sex

Pedigree Symbols

Aborted or stillborn

Pedigree Symbols

Deceased

Pedigree Symbols

Affected individual

Pedigree Symbols

Heterozygousindividual

Pedigree Symbols

X-linked carrier (remember: only woman can be X-linked carriers)

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.

Drawing a pedigree

I

II

III

1

1

1

2

2

2

3

3

4

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

Afflicted Males

More afflicted men than women

Afflicted Males

AfflictedFemales

“Equal” Afflicted Men and Women

Autosomal Dominant

Parent with Trait

Autosomal Recessive

Parent can exhibit trait

SkipsGeneration

AutosomalAA Aa aa

Dominant

Recessive

Sex-linked

X-linked Dominant

X-linked Recessive

XAXA

XAXA

XAXa

XAXa

XaXa

XaXa

XaY

XaY

XAY

XAY

Sex-linked Recessive

Autosomal Dominant

Autosomal Dominant

Sex-linked Recessive

Describe this family

Autosomal Recessive

Label the genotypesAutosomal recessive

aa

aa

aaaa

aa

Aa

Aa

AaAa

Aa

? ?

Describe this family

Sex-linked Dominant

Label the genotypesSex-linked Dominant

XAY XaXa XAXa

XaY XAXa?XAY

?

XAXa XAXaXAXa

XaY XaY XaY