Lec14 Pedigree Analysis Exercise
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Transcript of Lec14 Pedigree Analysis Exercise
pedigreeANALYSIS E X E R C I S E
Biology 3 Kawashima
General Notes
• Each set of slides will show a specific inheritance pattern
• The pedigrees are independent for every new inheritance pattern.
• The first slide of each set will show parental genotypes. Try to figure out the genotypes of the succeeding generations
• Answers and explanations are revealed in succeeding slide. NOTE: Answers revealed may not be the only set of correct answers.
START E X E R C I S E
Biology 3 Kawashima
AutosomalDominant
1 2
4 53
7
6
8
AA aa
AutosomalDominant
• Presence of even one dominant allele A gives the phenotype
• F1 only has one possible genotype Aa
• Crossing 3 and 4 may give either Aa|aa, but as 7 is unaffected, it must be aa
1 2
4 53
7
6
8
AA aa
Aa Aa aaaa
aa Aa
AutosomalDominant
• Crossing 5 and 6 may give either Aa|aa, but as 7 is affected, it must be Aa
• NOT sex-limited because it occurs in both sexes.
• NOT sex-influenced because the heterozygous genotype is expressed in the same way by both sexes (see 4 and 5)
1 2
4 53
7
6
8
AA aa
Aa Aa aaaa
aa Aa
AutosomalDominant
• NOT X-linked dominant nor recessive, if so 7 should also express the phenotype
• NOT Y-linked as it is also observed in females
1 2
4 53
7
6
8
AA aa
Aa Aa aaaa
aa Aa
AutosomalRecessive
1 2
4 53
7
6
aa AA
8
AutosomalRecessive
• Presence of two alleles aa gives the phenotype
• Presence of only one allele a will not exhibit the phenotype
• F1 only has one possible genotype Aa
• Crossing 3 and 4 may give either Aa|aa, but as 7 is unaffected, it must be Aa
1 2
4 53
7
6
aa AA
Aa Aaaa
Aa aa
Aa
8
AutosomalRecessive
• Crossing 5 and 6 may give AA|Aa|aa, but as 7 is affected, it must be only aa
• NOT sex-limited because it occurs in both sexes.
• NOT sex-influenced because the heterozygous genotype is expressed in the same way by both sexes (see 4 and 5)
1 2
4 53
7
6
aa AA
Aa Aaaa
Aa aa
Aa
8
AutosomalRecessive
• NOT X-linked dominant nor recessive, if so 5 (which is a carrier) crossed with 6, it is not possible for 8 to express the phenotype
• NOT Y-linked as it is also observed in females
1 2
4 53
7
6
aa AA
Aa Aaaa
Aa aa
Aa
8
AutosomalDominant Sex-Limited
1 2
4 53
7
6
8 9 10
AA aa
AutosomalDominant Sex-Limited
• Phenotype is male-limited• Presence of even one
dominant allele A in males gives the phenotype
• Females are not affected regardless of genotype
• F1 only has 1 possible genotype Aa
• Crossing 3 and 4 may give either Aa|aa, but either way 7 is unaffected because it is male-limited
1 2
4 53
7
6
8
AA aa
Aa AaAA
AA Aa
aa
9
Aa
10
aa
AutosomalDominant Sex-Limited
• Crossing 5 and 6 may give either Aa|aa, but as 8 is affected, it must be Aa
• Phenotype of 9 does not matter because it is male-limited
• Genotype of 10 is aa because it is an unaffected male
1 2
4 53
7
6
8
AA aa
Aa AaAA
AA Aa
aa
9
Aa
10
aa
AutosomalDominant Sex-Limited
• NOT simple dominance| recessiveness because females do not express the phenotype at all
• NOT sex-influenced. Though genders show different phenotypes for the same genotype, one sex (females in this case) are unaffected whatever the genotype (see 7)
1 2
4 53
7
6
8
AA aa
Aa AaAA
AA Aa
aa
9
Aa
10
aa
AutosomalDominant Sex-Limited
• NOT X-linked dominant|recessive because it is not observed in females.
• NOT Y-linked, if so 8 should not be affected as his father isn’t
1 2
4 53
7
6
8
AA aa
Aa AaAA
AA Aa
aa
9
Aa
10
aa
AutosomalRecessive Sex-Limited
1 2
4 53
7
6
8 9 10
aa AA
AutosomalRecessive Sex-Limited
• Phenotype is male-limited• Presence of both alleles aa
in males gives the phenotype
• Presence of only one allele a will not exhibit the phenotype
• Females are not affected regardless of genotype
• F1 only has 1 possible genotype Aa
1 2
4 53
7
6
8 9 10
aa AA
Aa AaAA
AA aa
Aa
Aa aa
AutosomalRecessive Sex-Limited
• Crossing 3 and 4 may give either Aa|aa, but either way 7 is unaffected because it is male-limited
• Crossing 5 and 6 may give AA|Aa|aa. Since 8 and 10 are affected, they are aa. 7 is unaffected regardless of genotype because it is male-limited
1 2
4 53
7
6
8 9 10
aa AA
Aa AaAA
AA aa
Aa
Aa aa
AutosomalRecessive Sex-Limited
• NOT simple dominance| recessiveness because females do not express the phenotype at all
• NOT sex-influenced because the heterozygous genotype is expressed in the same way by both sexes (see 4 and 5)
1 2
4 53
7
6
8 9 10
aa AA
Aa AaAA
AA aa
Aa
Aa aa
AutosomalRecessive Sex-Limited
• NOT X-linked dominant|recessive because it is not observed in females.
• NOT Y-linked, if so 4 should be affected
1 2
4 53
7
6
8 9 10
aa AA
Aa AaAA
AA aa
Aa
Aa aa
Autosomal Sex-Influenced
1 2
4 53
7
6
8 9 10
AA aa
Autosomal Sex-Influenced
• Phenotype expression changes between males and females.
• For this example, trait is dominant in males while recessive in females.
• In males, one allele A elicits the trait while in females, homozygous allele A is required for expression
1 2
4 53
7
6
8 9 10
AA aa
Aa AaAa
AA aa
aa
Aa Aa
Autosomal Sex-Influenced
• Heterozygote males and females express different phenotypes (see 4 and 5)
• Crossing 3 and 4 may give AA|Aa|aa, but as 7 is an affected female, it must be AA
• Crossing 5 and 6 may give Aa|aa. If 8 is an unaffected male, it must be aa while 9 being an unaffected female, she could be Aa or aa.
1 2
4 53
7
6
8 9 10
AA aa
Aa AaAa
AA aa
aa
Aa Aa
Autosomal Sex-Influenced
• Since 10 is an affected male, he can only be Aa
• NOT simple dominance| recessiveness because heterozygote males and females express different phenotypes.
• NOT sex-limited because it occurs in both sexes.
1 2
4 53
7
6
8 9 10
AA aa
Aa AaAa
AA aa
aa
Aa Aa
Autosomal Sex-Influenced
• NOT likely to be X-linked dominant nor recessive
• NOT Y-linked as it is also observed in females
1 2
4 53
7
6
8 9 10
AA aa
Aa AaAa
AA aa
aa
Aa Aa
X-Dominant Sex-Linked
1 2
4 53
7
6
8 9 10
XAY XX
X-Dominant Sex-Linked
• Alleles are found on the X chromosome
• Males with an XA chromosome always expresses the phenotype as he only can only have one X chromosome, thus only one copy (called hemizygous)
1 2
4 53
7
6
8 9 10
XAY XX
XY XAXXAX
XAX XAY
XY
XAX XY
X-Dominant Sex-Linked
• The X chromosome of males always come from their mother
• A male with a heterozygous affected mother has a ½ chance of also having the phenotype.
• A male with a homozygous affected mother will always have the phenotype.
1 2
4 53
7
6
8 9 10
XAY XX
XY XAXXAX
XAX XAY
XY
XAX XY
X-Dominant Sex-Linked
• A female with an affected father will always show the phenotype
• NOT simple dominance| recessiveness if parents are homozygotes. If this is not given/assumed it is indistinguishable.
• NOT sex-limited because it occurs in both sexes.
1 2
4 53
7
6
8 9 10
XAY XX
XY XAXXAX
XAX XAY
XY
XAX XY
X-Dominant Sex-Linked
• NOT sex-influenced. If pattern is dominant in males, recessive in females (or other way around), the pedigree is inconsistent
• NOT Y-linked because it is observed in females
1 2
4 53
7
6
8 9 10
XAY XX
XY XAXXAX
XAX XAY
XY
XAX XY
X-Recessive Sex-Linked
1 2
4 53
7
6
8 9 10
XaY XX
X-Recessive Sex-Linked
• Alleles are found on the X chromosome
• Males with an XA chromosome always expresses the phenotype as he only can only have one X chromosome, thus only one copy (called hemizygous)
1 2
4 53
7
6
8 9 10
XaY XX
XY XaXXaXa
XaX XaY
XY
XX XY
X-Recessive Sex-Linked
• The X chromosome of males always come from their mother
• A male with an affected mother will always also show the phenotype.
• A female with an affected father may or may not have the same phenotype
1 2
4 53
7
6
8 9 10
XaY XX
XY XaXXaXa
XaX XaY
XY
XX XY
X-Recessive Sex-Linked
• NOT simple dominance| recessiveness if parents are homozygotes. If this is not given/assumed it is indistinguishable.
• NOT sex-limited because it occurs in both sexes.
• NOT sex-influenced if parents are homozygotes. If not, it is indistinguishable.
• NOT Y-linked because it is observed in females
1 2
4 53
7
6
8 9 10
XaY XX
XY XaXXaXa
XaX XaY
XY
XX XY
Y Sex-Linked
1 2
4 53 6
8 9 10
XY* XX
8
Y Sex-Linked
• Allele is found on the Y chromosome
• Only males have a Y chromosome and are the only ones with a chance of expressing the trait. This is called a HOLANDRIC trait.
• NOT simple dominance| recessiveness
1 2
4 53 6
8 9 10
XY* XX
XY* XXXX
XY* XY
XY
XX XY
8
Y Sex-Linked
• NOT sex-limited because all males with an affected father will always express the trait.
• NOT sex-influenced as it is never expressed in females.
• NOT X-linked because it is not observed in females
1 2
4 53 6
8 9 10
XY* XX
XY* XXXX
XY* XY
XY
XX XY
8