Modes Of Inheritance

Question 1

What is an autosomal dominant condition?

Answer 1

A condition where only one faulty allele is needed for the condition to be expressed

Question 2

Who do autosomal dominant conditions manifest in?

Answer 2

They mainfest in heterozygotes

Question 3

What are the effects of autosomal dominant conditions?

Answer 3

1. Gain of function
2. Insufficient amounts of protein being produced
3. Dominant negative effect

Question 4

What is an example of an autosomal dominant condition?

Answer 4

Huntingtons

Question 5

What type of pedigree pattern do autosomal dominant conditions show?

Answer 5

Vertical pedigree pattern

Question 6

What causes Huntingtons disease ?

Answer 6

expansion of a CAG repeat which results in mutant huntingtin protein being produced

Question 7

What are the results of the mutation in Huntington’s disease?

Answer 7

Abnormal huntingtin is produced.
this aggregates and gains a pathological function, affecting neurones=> cell death

Question 8

which cells is abnormal huntingtin protein toxic to?

Answer 8

neurons, leading in cell death + decreased motor function

Question 9

What is meant by gain of function?

Answer 9

Gene now makes a protein with a new function

Question 10

What is meant by a dominant negative effect?

Answer 10

where the mutant protein produced interferes with the functioning of the normal protein

Question 11

What causes osteogenesis imperfecta (OI)?

Answer 11

mutations in type I, II,III, IV collagen

Question 12

what do the mutations in OI lead to?

Answer 12

weakening connective tissue particularly bone (brittle bones)

Question 13

How do autosomal dominant conditions effect men and women?

Answer 13

They affect men and women equally

Question 14

What are autosomal recessive conditions?

Answer 14

where you need two copies of the allele in order for the condition to be expressed

Question 15

What are the usual effects of autosomal recessive conditions?

Answer 15

Loss of function - having both copies results in a completely malfunctioning protein

Question 16

What type of pedigree pattern do autosomal recessive conditions show?

Answer 16

Horizontal pedigree

Question 17

What can increase the risk of autosomal recessive conditions?

Answer 17

Consangious marriages

Question 18

Why can autosomal recessive conditions skip generations?

Answer 18

Due to the high chance of being a carrier

Question 19

How are men and women affected with autosomal recessive conditions?

Answer 19

They are affected equally

Question 20

What type of chromosomes are autosomal recessive genes located on?

Answer 20

Non-sex chromosomes

Question 21

give an example of an autosomal recessive disorder?

Answer 21

cystic fibrosis

Question 22

Who do X-linked recessive conditions mainly affect?

Answer 22

Men

Question 23

What mutations cause CF?

Answer 23

various mutations in gene encoding chloride ion channel

Question 24

what do the mutations in CF lead to?

Answer 24

defective chloride channel (loss of function)

Question 25

How can females have an X linked recessive condition?

Answer 25

They have to be homozygous for the condition

Question 26

What is the chance of a daughter of an affected male being a carrier of an X Linked recessive condition?

Answer 26

100%

Question 27

What is an X linked recessive condition?

Answer 27

Where the alleles are located on the sex chroosomes, and since males have XY, a portion of their second chromosome is missing, meaning males have an increased risk of the condition as if they only need the one recessive allele to have the condition

Question 28

What happens to the daughters and sons of an affected father and unaffected mother of an X linked dominant condition?

Answer 28

Daughters - They are all affected
Sons - none affected

Question 29

Give an example of an X-linked dominant disorder

Answer 29

hypophosphatemia

Question 30

Explain the pathophysiology of hypophosphatemia

Answer 30

overproduction of FGF21
this inhibits kidney phosphate resorption

Question 31

Who do Y linked disorders affect?

Answer 31

Only men as females do not have Y chromosome

Question 32

What type of pedigree pattern do Y linked disorders show?

Answer 32

Vertical patern with only males affected

Question 33

Who are all your mitochondria inherited from?

Answer 33

Mother

Question 34

A mother has a mitochondrial condition. What happens to her children?

Answer 34

They are all affected

Question 35

Why do the expression of mitochondrial conditions vary massively in a family?

Answer 35

Mitochondria have multiple copies of their genome where there’s some normal and some mutant. The mitochondria only express the disease effects above a threshold of mutated copies.

You can inherit a combination of these genes, resulting in variability amongst offspring

Question 36

What type of inheritance is it when children of unaffected parents are affected?

Answer 36

X Linked recessive

Question 37

What type of inheritance is it when all children of an affected mother are affected?

Answer 37

Mitochondrial

Question 38

what type of functions do mitochondrial disorders tend to affect?

Answer 38

motor + nerve function

Question 39

give an example of a mitochondrial disease

Answer 39

leber’s hereditary optic neuropathy (LHON)