Inheritance Patterns

Question 1

How are males represented in a pedigree drawing?

Answer 1

Squares

Question 2

How are females represented in a pedigree drawing?

Answer 2

Circle

Question 3

How are siblings represented in a pedigree drawing?

Answer 3

Line above them

Question 4

How are partners represented in a pedigree drawing?

Answer 4

Line between them

Question 5

How are affected people represented in a pedigree drawing?

Answer 5

Shaded in

Question 6

How are carriers represented in a pedigree drawing?

Answer 6

Dots in their shape

Question 7

How are children represented in a pedigree drawing?

Answer 7

Line down

Question 8

How are consanguineous partners represented in a pedigree drawing?

Answer 8

Double line

Question 9

What does SB mean in a pedigree drawing?

Answer 9

Still born

Question 10

How are people of unknown sex represented in a pedigree drawing?

Answer 10

Diamond

Question 11

How are miscarriages represented in a pedigree drawing?

Answer 11

Triangle

Question 12

How is an abortion represented in a pedigree drawing?

Answer 12

Triangle with a line through

Question 13

How are foetus’ of unknown sex represented in a pedigree drawing?

Answer 13

Diamond with a P inside

Question 14

How are identical twins represented in a pedigree drawing?

Answer 14

Horizontal line between two diagonal lines

Question 15

How are non-identical twins represented in a pedigree drawing?

Answer 15

Two diagonal lines

Question 16

What is penetrance?

Answer 16

The percentage of individuals that carry the mutation and develop symptoms of the disorder

Question 17

Give some characteristics of autosomal dominant inheritance

Answer 17

• most affected individuals have an affected parent

- both sexes equally likely to inherit the allele

Question 18

What is the risk for each child of an affected parent in autosomal dominant inheritance?

Answer 18

1/2

Question 19

Can unaffected siblings of an affected individual pass the mutation on in autosomal dominant inheritance?

Answer 19

No

Question 20

What are obligate carriers?

Answer 20

Individuals that have the disease causing genotype but haven’t developed the disease

Question 21

What is variable expressivity?

Answer 21

Variation in the severity or symptoms of disorder between individuals with the same mutation

Question 22

What is somatic mosaicism?

Answer 22

When a new mutation arises at an early stage in embryogenesis

Question 23

What does somatic mosaicism mean for the cells of the individual?

Answer 23

The mutation will only be present in some tissues/ cells

Question 24

What is germ-line/gonadal mosaicism?

Answer 24

When a new mutation arises during oogenesis or spermatogenesis

Question 25

What does germ-line/gonadal mosaicism mean for the individual?

Answer 25

The mutation is present in a variable proportion of gametes and can be transmitted to the offspring

Question 26

What does anticipation mean in autosomal dominant inheritance?

Answer 26

Worsening of disease severity in successive generations

Question 27

When does anticipation characteristically occur?

Answer 27

In triplet repeat disorders

Question 28

Give some characteristics of autosomal recessive inheritance

Answer 28

• may be due to consanguinity
• usually one generation is affected
• both sexes are affected and its transmissible between sexes

Question 29

Are heterozygotes affected by autosomal recessive inheritance?

Answer 29

No

Question 30

What genotypes are affected by autosomal recessive inheritance?

Answer 30

Homozygous and compound heterozygous

Question 31

What does compound heterozygous mean?

Answer 31

Two different mutations on the same gene which basically causes homozygosity

Question 32

What is the recurrence risk for a sibling of an affected person in autosomal recessive disease?

Answer 32

1/4

Question 33

What is the carrier risk for a sibling of an affected person in autosomal recessive disease?

Answer 33

2/3

Question 34

What does it mean for males and females if an X-linked trait is recessive?

Answer 34

Males can only be hemizygous but females can be homozygous or heterozygous

Question 35

What does it mean for males and females if an X-linked trait is recessive?

Answer 35

Women are unaffected carriers and there is no male -> male transmission

Question 36

What does it mean for males and females if an X-linked trait is dominant?

Answer 36

Women are affected and males are more severely affected and could be lethal

Question 37

What is the likelihood a child of a carrier female will inherit the X-Linked mutant allele?

Answer 37

50%

Question 38

What is skewed X-Inactivation?

Answer 38

Generally random but roughly 10% of women have it

Question 39

What is a manifesting carrier of an X-linked condition?

Answer 39

When a women has some symptoms in X-linked recessive conditions even if they’re heterozygous

Question 40

What is another term for Y linked inheritance?

Answer 40

Holandric

Question 41

How is holandric inheritance passed on?

Answer 41

Father -> son

Question 42

What are the two types of insertion and deletion?

Answer 42

Inframe or frameshift

Question 43

What is an inframe insertion or deletion?

Answer 43

When the indel is divisible by a multiple of 3

Question 44

What is a frameshift insertion or deletion?

Answer 44

Not a multiple of three

Question 45

Is an inframe or frameshift indel more likely to be disease causing?

Answer 45

Frameshift